Case Reports

THE CASE

A 27-year-old woman in the 21st week of her first pregnancy came to our clinic complaining of a constant burning pain that spread around her left chest wall to her back. She graded the pain as a 10 on a 0 to 10 visual analog scale. The pain, which began 3 months earlier, became worse when she took a deep breath, ate, or walked, but was alleviated by applying warm compresses. Our patient hadn’t slept well since the pain began. Her medical history was noteworthy for chickenpox at age 5.

During the physical examination, palpating her left upper abdominal quadrant and left lower chest wall elicited tenderness. We noted allodynia and hyperesthesia in these regions, and the left T5 dermatome revealed extreme sensitivity.

THE DIAGNOSIS

We decided to test for antibodies to the varicella-zoster virus (VZV) based on the location of the pain along a dermatome. A serum anti-VZV immunoglobulin G (IgG) level was high at 1.9. Since our patient hadn’t been vaccinated against VZV, her high IgG level may have been the result of reactivation of the virus. Based on this test result and our patient’s history and physical exam findings (ie, neuropathic pain along a dermatome without a typical herpes zoster rash), we diagnosed zoster sine herpete (ZSH).

DISCUSSION

One million new cases of herpes zoster (shingles) are diagnosed in the United States each year, with a rate of 3 to 4 cases per 1000 people.¹ One in 3 patients develops postherpetic neuralgia, depending on age and immunocompetence.¹

In ZSH, the neuropathic pain of herpes zoster occurs without the typical zoster rash.² Since the rash is absent, the diagnosis is often missed. The incidence of ZSH is unknown.

Although many pregnant women suffer from thoracic and/or abdominal neuropathic pain, there are no reports in the literature that describe ZSH in pregnant women.³

Suspect zoster sine herpete in a patient who has neuropathic radicular pain but no rash.

The appropriate diagnostic tests for ZSH are polymerase chain reaction for VZV DNA and anti-VZV IgG.^2,4-7 A definitive diagnosis can be reached by identifying herpes zoster DNA in cerebrospinal fluid (CSF) and organism-specific immunoglobulins. However, a high titer of serum IgG antibodies or a positive IgM antibodies test typically provides a high degree of certainty for the diagnosis.⁸ For our patient, we decided not to test her CSF because we felt that her clinical course and positive IgG test were sufficient to establish the diagnosis.

The differential diagnosis of radicular pain during pregnancy includes cutaneous nerve entrapment. The expanding uterus could increase pressure on cutaneous nerves in the abdominal wall and cause pain. Although nerve entrapment would be expected to cause impingement and sometimes hypoesthesia, ZSH usually causes allodynia and hyperesthesia, as was the case in our patient.³

Pregnancy affects choice of treatment

Treatments for ZSH include acyclovir and local anesthesia.⁸ A single injection of lidocaine (8 cc) may completely eliminate the ZSH pain by affecting the nerve action potential.⁹ Corticosteroids are used to suppress inflammation and decrease erythema, swelling, warmth at the site, and local tenderness.

Our patient. We decided to treat our patient with only a nerve block because the potential adverse effects of acyclovir in the second trimester of pregnancy are unclear.¹⁰ She received 1 cc of betamethasone acetate (3 mg) and betamethasone sodium phosphate (3 mg) and 8 cc of 2% lidocaine. The patient reported immediate pain relief, which lasted until delivery.

THE TAKEAWAY

ZSH is characterized by neuropathic pain along a dermatome that’s associated with herpes zoster and is not accompanied by the characteristic rash. Many pregnant women suffer from thoracic and abdominal wall neuropathic pain. Neuropathic radicular pain in the absence of a rash should raise suspicion of ZSH. Considering this syndrome at an early stage can avert unnecessary testing and reduce the patient’s pain.

THE CASE

A 27-year-old woman in the 21st week of her first pregnancy came to our clinic complaining of a constant burning pain that spread around her left chest wall to her back. She graded the pain as a 10 on a 0 to 10 visual analog scale. The pain, which began 3 months earlier, became worse when she took a deep breath, ate, or walked, but was alleviated by applying warm compresses. Our patient hadn’t slept well since the pain began. Her medical history was noteworthy for chickenpox at age 5.

During the physical examination, palpating her left upper abdominal quadrant and left lower chest wall elicited tenderness. We noted allodynia and hyperesthesia in these regions, and the left T5 dermatome revealed extreme sensitivity.

THE DIAGNOSIS

We decided to test for antibodies to the varicella-zoster virus (VZV) based on the location of the pain along a dermatome. A serum anti-VZV immunoglobulin G (IgG) level was high at 1.9. Since our patient hadn’t been vaccinated against VZV, her high IgG level may have been the result of reactivation of the virus. Based on this test result and our patient’s history and physical exam findings (ie, neuropathic pain along a dermatome without a typical herpes zoster rash), we diagnosed zoster sine herpete (ZSH).

DISCUSSION

One million new cases of herpes zoster (shingles) are diagnosed in the United States each year, with a rate of 3 to 4 cases per 1000 people.¹ One in 3 patients develops postherpetic neuralgia, depending on age and immunocompetence.¹

In ZSH, the neuropathic pain of herpes zoster occurs without the typical zoster rash.² Since the rash is absent, the diagnosis is often missed. The incidence of ZSH is unknown.

Although many pregnant women suffer from thoracic and/or abdominal neuropathic pain, there are no reports in the literature that describe ZSH in pregnant women.³

Suspect zoster sine herpete in a patient who has neuropathic radicular pain but no rash.

The appropriate diagnostic tests for ZSH are polymerase chain reaction for VZV DNA and anti-VZV IgG.^2,4-7 A definitive diagnosis can be reached by identifying herpes zoster DNA in cerebrospinal fluid (CSF) and organism-specific immunoglobulins. However, a high titer of serum IgG antibodies or a positive IgM antibodies test typically provides a high degree of certainty for the diagnosis.⁸ For our patient, we decided not to test her CSF because we felt that her clinical course and positive IgG test were sufficient to establish the diagnosis.

The differential diagnosis of radicular pain during pregnancy includes cutaneous nerve entrapment. The expanding uterus could increase pressure on cutaneous nerves in the abdominal wall and cause pain. Although nerve entrapment would be expected to cause impingement and sometimes hypoesthesia, ZSH usually causes allodynia and hyperesthesia, as was the case in our patient.³

Pregnancy affects choice of treatment

Treatments for ZSH include acyclovir and local anesthesia.⁸ A single injection of lidocaine (8 cc) may completely eliminate the ZSH pain by affecting the nerve action potential.⁹ Corticosteroids are used to suppress inflammation and decrease erythema, swelling, warmth at the site, and local tenderness.

Our patient. We decided to treat our patient with only a nerve block because the potential adverse effects of acyclovir in the second trimester of pregnancy are unclear.¹⁰ She received 1 cc of betamethasone acetate (3 mg) and betamethasone sodium phosphate (3 mg) and 8 cc of 2% lidocaine. The patient reported immediate pain relief, which lasted until delivery.

THE TAKEAWAY

ZSH is characterized by neuropathic pain along a dermatome that’s associated with herpes zoster and is not accompanied by the characteristic rash. Many pregnant women suffer from thoracic and abdominal wall neuropathic pain. Neuropathic radicular pain in the absence of a rash should raise suspicion of ZSH. Considering this syndrome at an early stage can avert unnecessary testing and reduce the patient’s pain.

THE CASE

A 27-year-old woman in the 21st week of her first pregnancy came to our clinic complaining of a constant burning pain that spread around her left chest wall to her back. She graded the pain as a 10 on a 0 to 10 visual analog scale. The pain, which began 3 months earlier, became worse when she took a deep breath, ate, or walked, but was alleviated by applying warm compresses. Our patient hadn’t slept well since the pain began. Her medical history was noteworthy for chickenpox at age 5.

During the physical examination, palpating her left upper abdominal quadrant and left lower chest wall elicited tenderness. We noted allodynia and hyperesthesia in these regions, and the left T5 dermatome revealed extreme sensitivity.

THE DIAGNOSIS

We decided to test for antibodies to the varicella-zoster virus (VZV) based on the location of the pain along a dermatome. A serum anti-VZV immunoglobulin G (IgG) level was high at 1.9. Since our patient hadn’t been vaccinated against VZV, her high IgG level may have been the result of reactivation of the virus. Based on this test result and our patient’s history and physical exam findings (ie, neuropathic pain along a dermatome without a typical herpes zoster rash), we diagnosed zoster sine herpete (ZSH).

DISCUSSION

One million new cases of herpes zoster (shingles) are diagnosed in the United States each year, with a rate of 3 to 4 cases per 1000 people.¹ One in 3 patients develops postherpetic neuralgia, depending on age and immunocompetence.¹

In ZSH, the neuropathic pain of herpes zoster occurs without the typical zoster rash.² Since the rash is absent, the diagnosis is often missed. The incidence of ZSH is unknown.

Although many pregnant women suffer from thoracic and/or abdominal neuropathic pain, there are no reports in the literature that describe ZSH in pregnant women.³

Suspect zoster sine herpete in a patient who has neuropathic radicular pain but no rash.

The appropriate diagnostic tests for ZSH are polymerase chain reaction for VZV DNA and anti-VZV IgG.^2,4-7 A definitive diagnosis can be reached by identifying herpes zoster DNA in cerebrospinal fluid (CSF) and organism-specific immunoglobulins. However, a high titer of serum IgG antibodies or a positive IgM antibodies test typically provides a high degree of certainty for the diagnosis.⁸ For our patient, we decided not to test her CSF because we felt that her clinical course and positive IgG test were sufficient to establish the diagnosis.

The differential diagnosis of radicular pain during pregnancy includes cutaneous nerve entrapment. The expanding uterus could increase pressure on cutaneous nerves in the abdominal wall and cause pain. Although nerve entrapment would be expected to cause impingement and sometimes hypoesthesia, ZSH usually causes allodynia and hyperesthesia, as was the case in our patient.³

Pregnancy affects choice of treatment

Treatments for ZSH include acyclovir and local anesthesia.⁸ A single injection of lidocaine (8 cc) may completely eliminate the ZSH pain by affecting the nerve action potential.⁹ Corticosteroids are used to suppress inflammation and decrease erythema, swelling, warmth at the site, and local tenderness.

Our patient. We decided to treat our patient with only a nerve block because the potential adverse effects of acyclovir in the second trimester of pregnancy are unclear.¹⁰ She received 1 cc of betamethasone acetate (3 mg) and betamethasone sodium phosphate (3 mg) and 8 cc of 2% lidocaine. The patient reported immediate pain relief, which lasted until delivery.

THE TAKEAWAY

ZSH is characterized by neuropathic pain along a dermatome that’s associated with herpes zoster and is not accompanied by the characteristic rash. Many pregnant women suffer from thoracic and abdominal wall neuropathic pain. Neuropathic radicular pain in the absence of a rash should raise suspicion of ZSH. Considering this syndrome at an early stage can avert unnecessary testing and reduce the patient’s pain.

THE CASE

A 55-year-old woman presented to the emergency department (ED) with a bifrontal headache that she’d had for one day. She also had blurred vision and was vomiting shortly before coming to the hospital. The patient had no history of hypertension, migraine headaches, seizure disorder, autoimmune disorders, or cerebrovascular disease.

Her vital signs, including a blood pressure of 114/63 mm Hg, were normal, but a physical examination revealed subjective vision loss. She was only able to see objects moving on a horizontal plane. Her finger-to-nose exam, pupillary reflexes, and extra-ocular movements were normal, but peripheral vision was limited on her left side. No other neurologic deficits were noted.

The patient was admitted to the hospital and most of her laboratory work-up was normal, including a basic metabolic panel, complete blood count, coagulation studies, brain natriuretic peptide test, and cardiac enzymes. Her white blood cell count was 19,700/mcL, but no source of infection was found. A computed tomography (CT) scan of her head without contrast showed low-density, patchy areas in the subcortical regions of the parietal and occipital lobes bilaterally (FIGURE 1, arrows), with relative sparing of the cortex.

THE DIAGNOSIS

Based on our patient’s presentation and radiologic findings, we made a diagnosis of posterior reversible encephalopathy syndrome (PRES). However, because we could not rule out an ischemic cerebrovascular event at the time of presentation, we started the patient on aspirin and clopidogrel 75 mg to prevent possible future ischemic events. The next day, we ordered magnetic resonance imaging (MRI) of the head and neck, which documented the edema and confirmed the diagnosis of PRES (FIGURE 2).

DISCUSSION

PRES is a neurotoxic state associated with a unique pattern of brain vasogenic edema seen on CT or MRI. The edema is often widespread but is predominantly found in the parietal and occipital regions.¹ PRES is seen in patients with a variety of conditions, including hypertension and bone marrow or organ transplantation, as well as in those receiving immunosuppressive or cytotoxic medications.¹ Patients with PRES typically present with headaches and seizures.² Visual abnormalities (most commonly cortical blindness), occur in 15% to 20% of patients with PRES.^2-4

Hinchey et al³ first described reversible posterior leukoencephalopathy syndrome (which later became known as PRES) in 1996. Most of the 15 patients included in this original report had a history of hypertension or immunosuppression. These cases were associated with cerebral edema in portions of the posterior cerebral white matter. It is thought that hypertension alters the blood-brain barrier and causes the acute changes that occur in PRES.³

Besides hypertension and immunosuppression, the risk factors most commonly associated with PRES include preeclampsia/eclampsia; sepsis, particularly due to grampositive organisms; Wegener’s granulomatosis, scleroderma, and polyarteritis nodosa; cancer chemotherapy; bone marrow or stem cell transplantation; and renal disease.^1,4-6

Although a clear cause of PRES has not yet been established, researchers have proposed 2 theories. The first postulates that a sudden increase in systemic blood pressure causes vasoconstriction, which leads to ischemia and edema.^1-4,7,8 However, several studies have also described cases of PRES in patients with mild elevations in blood pressure,^1,5-7 and mild edema has been observed even in normotensive patients^1,5 (as was the case with our patient).

The second theory links PRES to the loss of brain autoregulation, a function that maintains steady blood flow when blood pressure fluctuates.⁶ A loss of this regulatory mechanism causes endothelial dysfunction, capillary leakage, and disruption in the blood-brain barrier.^1,2,4,6-8 These changes then lead to cerebral vasodilatation and edema.² Immunotherapy has also been associated with increased endothelial dysfunction.²

The evidence on the link between the severity of PRES and clinical outcomes is conflicting.

One study that followed 113 PRES patients over 6 years did not find an association between the severity of clinical presentation and the extent of vasogenic edema found on imaging studies.⁵ Of these 113 patients, 69 had PRES primarily due to hypertension, and 21 were receiving cytotoxic medications.⁵ In contrast, a larger retrospective study that followed patients with PRES for 12 years found that severe cases, which included patients with severe cerebral edema and altered mental status, had poor outcomes.⁴ Small studies have reported that 14% of patients with PRES develop cerebral hemorrhage.⁸

When to suspect this condition. PRES should be part of the differential diagnosis for any patient who presents with headache and vision loss. It is important to distinguish PRES from an acute cerebrovascular accident (CVA) because the 2 conditions are managed differently.² In addition, PRES lesions can be misdiagnosed as tumors, especially in a patient with a history of malignant disease in whom the condition appears after chemotherapy.⁹

 

Treatment targets the underlying causes

Treatment options for PRES are limited. Hypertension in a patient with PRES requires prompt intervention to avoid progression of the disease.² The use of intravenous (IV) calcium-channel blockers or IV beta-blockers for these patients is common.^2,8

Patients with seizures should be treated with anticonvulsant medication, but longterm antiepileptic treatment usually is not required.² Patients who take immunosuppressant or cytotoxic drugs should stop them indefinitely upon presenting with PRES.²

PRES lesions can be misdiagnosed as tumors—especially in patients with a history of malignant disease who have undergone chemotherapy.

For a pregnant woman with preeclampsia/eclampsia, delivery of the placenta, which is considered to be the cause of PRES in these cases, is curative.¹ However, women can develop PRES several weeks after delivery.¹

In most cases, the symptoms associated with PRES will resolve once treatment is initiated, and neurologic recovery can be expected within 2 weeks.²

Our patient regained her sight the following morning and was discharged home 2 days after admission. Her blood pressure remained normal. She returned to the hospital unresponsive the day after she had been discharged. Family members stated that she had taken 15 packets of an aspirin/caffeine combination to control a new headache.

Her blood pressure was elevated at 159/79 mm Hg. A CT of the brain showed a hemorrhagic stroke within the left occipital lobe and posterior parietal lobe with a midline shift of 8 mm. We don’t know if the aspirin use contributed to the hemorrhagic event or if it was a sequela of PRES.

The patient died 4 days later.

THE TAKEAWAY

PRES is a neurotoxic condition that causes headache, seizures, and vision loss. Most patients will present with elevated blood pressure and imaging studies will reveal a specific pattern of vasogenic edema that is predominately found in the parietal and occipital regions.

Treating the hypertension may result in a more favorable recovery. Normotensive patients are harder to treat because there is no specific therapy for PRES. Follow-up imaging may help to assess the resolution of the syndrome.

THE CASE

A 55-year-old woman presented to the emergency department (ED) with a bifrontal headache that she’d had for one day. She also had blurred vision and was vomiting shortly before coming to the hospital. The patient had no history of hypertension, migraine headaches, seizure disorder, autoimmune disorders, or cerebrovascular disease.

Her vital signs, including a blood pressure of 114/63 mm Hg, were normal, but a physical examination revealed subjective vision loss. She was only able to see objects moving on a horizontal plane. Her finger-to-nose exam, pupillary reflexes, and extra-ocular movements were normal, but peripheral vision was limited on her left side. No other neurologic deficits were noted.

The patient was admitted to the hospital and most of her laboratory work-up was normal, including a basic metabolic panel, complete blood count, coagulation studies, brain natriuretic peptide test, and cardiac enzymes. Her white blood cell count was 19,700/mcL, but no source of infection was found. A computed tomography (CT) scan of her head without contrast showed low-density, patchy areas in the subcortical regions of the parietal and occipital lobes bilaterally (FIGURE 1, arrows), with relative sparing of the cortex.

THE DIAGNOSIS

Based on our patient’s presentation and radiologic findings, we made a diagnosis of posterior reversible encephalopathy syndrome (PRES). However, because we could not rule out an ischemic cerebrovascular event at the time of presentation, we started the patient on aspirin and clopidogrel 75 mg to prevent possible future ischemic events. The next day, we ordered magnetic resonance imaging (MRI) of the head and neck, which documented the edema and confirmed the diagnosis of PRES (FIGURE 2).

DISCUSSION

PRES is a neurotoxic state associated with a unique pattern of brain vasogenic edema seen on CT or MRI. The edema is often widespread but is predominantly found in the parietal and occipital regions.¹ PRES is seen in patients with a variety of conditions, including hypertension and bone marrow or organ transplantation, as well as in those receiving immunosuppressive or cytotoxic medications.¹ Patients with PRES typically present with headaches and seizures.² Visual abnormalities (most commonly cortical blindness), occur in 15% to 20% of patients with PRES.^2-4

Hinchey et al³ first described reversible posterior leukoencephalopathy syndrome (which later became known as PRES) in 1996. Most of the 15 patients included in this original report had a history of hypertension or immunosuppression. These cases were associated with cerebral edema in portions of the posterior cerebral white matter. It is thought that hypertension alters the blood-brain barrier and causes the acute changes that occur in PRES.³

Besides hypertension and immunosuppression, the risk factors most commonly associated with PRES include preeclampsia/eclampsia; sepsis, particularly due to grampositive organisms; Wegener’s granulomatosis, scleroderma, and polyarteritis nodosa; cancer chemotherapy; bone marrow or stem cell transplantation; and renal disease.^1,4-6

Although a clear cause of PRES has not yet been established, researchers have proposed 2 theories. The first postulates that a sudden increase in systemic blood pressure causes vasoconstriction, which leads to ischemia and edema.^1-4,7,8 However, several studies have also described cases of PRES in patients with mild elevations in blood pressure,^1,5-7 and mild edema has been observed even in normotensive patients^1,5 (as was the case with our patient).

The second theory links PRES to the loss of brain autoregulation, a function that maintains steady blood flow when blood pressure fluctuates.⁶ A loss of this regulatory mechanism causes endothelial dysfunction, capillary leakage, and disruption in the blood-brain barrier.^1,2,4,6-8 These changes then lead to cerebral vasodilatation and edema.² Immunotherapy has also been associated with increased endothelial dysfunction.²

The evidence on the link between the severity of PRES and clinical outcomes is conflicting.

One study that followed 113 PRES patients over 6 years did not find an association between the severity of clinical presentation and the extent of vasogenic edema found on imaging studies.⁵ Of these 113 patients, 69 had PRES primarily due to hypertension, and 21 were receiving cytotoxic medications.⁵ In contrast, a larger retrospective study that followed patients with PRES for 12 years found that severe cases, which included patients with severe cerebral edema and altered mental status, had poor outcomes.⁴ Small studies have reported that 14% of patients with PRES develop cerebral hemorrhage.⁸

When to suspect this condition. PRES should be part of the differential diagnosis for any patient who presents with headache and vision loss. It is important to distinguish PRES from an acute cerebrovascular accident (CVA) because the 2 conditions are managed differently.² In addition, PRES lesions can be misdiagnosed as tumors, especially in a patient with a history of malignant disease in whom the condition appears after chemotherapy.⁹

 

Treatment targets the underlying causes

Treatment options for PRES are limited. Hypertension in a patient with PRES requires prompt intervention to avoid progression of the disease.² The use of intravenous (IV) calcium-channel blockers or IV beta-blockers for these patients is common.^2,8

Patients with seizures should be treated with anticonvulsant medication, but longterm antiepileptic treatment usually is not required.² Patients who take immunosuppressant or cytotoxic drugs should stop them indefinitely upon presenting with PRES.²

PRES lesions can be misdiagnosed as tumors—especially in patients with a history of malignant disease who have undergone chemotherapy.

For a pregnant woman with preeclampsia/eclampsia, delivery of the placenta, which is considered to be the cause of PRES in these cases, is curative.¹ However, women can develop PRES several weeks after delivery.¹

In most cases, the symptoms associated with PRES will resolve once treatment is initiated, and neurologic recovery can be expected within 2 weeks.²

Our patient regained her sight the following morning and was discharged home 2 days after admission. Her blood pressure remained normal. She returned to the hospital unresponsive the day after she had been discharged. Family members stated that she had taken 15 packets of an aspirin/caffeine combination to control a new headache.

Her blood pressure was elevated at 159/79 mm Hg. A CT of the brain showed a hemorrhagic stroke within the left occipital lobe and posterior parietal lobe with a midline shift of 8 mm. We don’t know if the aspirin use contributed to the hemorrhagic event or if it was a sequela of PRES.

The patient died 4 days later.

THE TAKEAWAY

PRES is a neurotoxic condition that causes headache, seizures, and vision loss. Most patients will present with elevated blood pressure and imaging studies will reveal a specific pattern of vasogenic edema that is predominately found in the parietal and occipital regions.

Treating the hypertension may result in a more favorable recovery. Normotensive patients are harder to treat because there is no specific therapy for PRES. Follow-up imaging may help to assess the resolution of the syndrome.

THE CASE

A 55-year-old woman presented to the emergency department (ED) with a bifrontal headache that she’d had for one day. She also had blurred vision and was vomiting shortly before coming to the hospital. The patient had no history of hypertension, migraine headaches, seizure disorder, autoimmune disorders, or cerebrovascular disease.

Her vital signs, including a blood pressure of 114/63 mm Hg, were normal, but a physical examination revealed subjective vision loss. She was only able to see objects moving on a horizontal plane. Her finger-to-nose exam, pupillary reflexes, and extra-ocular movements were normal, but peripheral vision was limited on her left side. No other neurologic deficits were noted.

The patient was admitted to the hospital and most of her laboratory work-up was normal, including a basic metabolic panel, complete blood count, coagulation studies, brain natriuretic peptide test, and cardiac enzymes. Her white blood cell count was 19,700/mcL, but no source of infection was found. A computed tomography (CT) scan of her head without contrast showed low-density, patchy areas in the subcortical regions of the parietal and occipital lobes bilaterally (FIGURE 1, arrows), with relative sparing of the cortex.

THE DIAGNOSIS

Based on our patient’s presentation and radiologic findings, we made a diagnosis of posterior reversible encephalopathy syndrome (PRES). However, because we could not rule out an ischemic cerebrovascular event at the time of presentation, we started the patient on aspirin and clopidogrel 75 mg to prevent possible future ischemic events. The next day, we ordered magnetic resonance imaging (MRI) of the head and neck, which documented the edema and confirmed the diagnosis of PRES (FIGURE 2).

DISCUSSION

PRES is a neurotoxic state associated with a unique pattern of brain vasogenic edema seen on CT or MRI. The edema is often widespread but is predominantly found in the parietal and occipital regions.¹ PRES is seen in patients with a variety of conditions, including hypertension and bone marrow or organ transplantation, as well as in those receiving immunosuppressive or cytotoxic medications.¹ Patients with PRES typically present with headaches and seizures.² Visual abnormalities (most commonly cortical blindness), occur in 15% to 20% of patients with PRES.^2-4

Hinchey et al³ first described reversible posterior leukoencephalopathy syndrome (which later became known as PRES) in 1996. Most of the 15 patients included in this original report had a history of hypertension or immunosuppression. These cases were associated with cerebral edema in portions of the posterior cerebral white matter. It is thought that hypertension alters the blood-brain barrier and causes the acute changes that occur in PRES.³

Besides hypertension and immunosuppression, the risk factors most commonly associated with PRES include preeclampsia/eclampsia; sepsis, particularly due to grampositive organisms; Wegener’s granulomatosis, scleroderma, and polyarteritis nodosa; cancer chemotherapy; bone marrow or stem cell transplantation; and renal disease.^1,4-6

Although a clear cause of PRES has not yet been established, researchers have proposed 2 theories. The first postulates that a sudden increase in systemic blood pressure causes vasoconstriction, which leads to ischemia and edema.^1-4,7,8 However, several studies have also described cases of PRES in patients with mild elevations in blood pressure,^1,5-7 and mild edema has been observed even in normotensive patients^1,5 (as was the case with our patient).

The second theory links PRES to the loss of brain autoregulation, a function that maintains steady blood flow when blood pressure fluctuates.⁶ A loss of this regulatory mechanism causes endothelial dysfunction, capillary leakage, and disruption in the blood-brain barrier.^1,2,4,6-8 These changes then lead to cerebral vasodilatation and edema.² Immunotherapy has also been associated with increased endothelial dysfunction.²

The evidence on the link between the severity of PRES and clinical outcomes is conflicting.

One study that followed 113 PRES patients over 6 years did not find an association between the severity of clinical presentation and the extent of vasogenic edema found on imaging studies.⁵ Of these 113 patients, 69 had PRES primarily due to hypertension, and 21 were receiving cytotoxic medications.⁵ In contrast, a larger retrospective study that followed patients with PRES for 12 years found that severe cases, which included patients with severe cerebral edema and altered mental status, had poor outcomes.⁴ Small studies have reported that 14% of patients with PRES develop cerebral hemorrhage.⁸

When to suspect this condition. PRES should be part of the differential diagnosis for any patient who presents with headache and vision loss. It is important to distinguish PRES from an acute cerebrovascular accident (CVA) because the 2 conditions are managed differently.² In addition, PRES lesions can be misdiagnosed as tumors, especially in a patient with a history of malignant disease in whom the condition appears after chemotherapy.⁹

 

Treatment targets the underlying causes

Treatment options for PRES are limited. Hypertension in a patient with PRES requires prompt intervention to avoid progression of the disease.² The use of intravenous (IV) calcium-channel blockers or IV beta-blockers for these patients is common.^2,8

Patients with seizures should be treated with anticonvulsant medication, but longterm antiepileptic treatment usually is not required.² Patients who take immunosuppressant or cytotoxic drugs should stop them indefinitely upon presenting with PRES.²

PRES lesions can be misdiagnosed as tumors—especially in patients with a history of malignant disease who have undergone chemotherapy.

For a pregnant woman with preeclampsia/eclampsia, delivery of the placenta, which is considered to be the cause of PRES in these cases, is curative.¹ However, women can develop PRES several weeks after delivery.¹

In most cases, the symptoms associated with PRES will resolve once treatment is initiated, and neurologic recovery can be expected within 2 weeks.²

Our patient regained her sight the following morning and was discharged home 2 days after admission. Her blood pressure remained normal. She returned to the hospital unresponsive the day after she had been discharged. Family members stated that she had taken 15 packets of an aspirin/caffeine combination to control a new headache.

Her blood pressure was elevated at 159/79 mm Hg. A CT of the brain showed a hemorrhagic stroke within the left occipital lobe and posterior parietal lobe with a midline shift of 8 mm. We don’t know if the aspirin use contributed to the hemorrhagic event or if it was a sequela of PRES.

The patient died 4 days later.

THE TAKEAWAY

PRES is a neurotoxic condition that causes headache, seizures, and vision loss. Most patients will present with elevated blood pressure and imaging studies will reveal a specific pattern of vasogenic edema that is predominately found in the parietal and occipital regions.

Treating the hypertension may result in a more favorable recovery. Normotensive patients are harder to treat because there is no specific therapy for PRES. Follow-up imaging may help to assess the resolution of the syndrome.

Case

A previously healthy 4-month-old girl was brought into the ED for concerns of alcohol ingestion. Reportedly, the infant’s father reconstituted 4 ounces of powdered formula using what he thought was water from an unmarked bottle in his refrigerator. He later realized that the bottle contained rum, although he still let the child finish the 4 ounces of formula in the hopes that she would vomit—which did not occur.

Upon arrival to the ED, the infant’s vital signs were: blood pressure, 100/61 mm Hg; heart rate, 155 beats/minute; respiratory rate, 36 breaths/minute; and temperature, normal. Oxygen saturation was 98% on room air. A rapid bedside blood glucose test was 89 mg/dL. The infant’s physical examination was unremarkable. She appeared active but hungry, had a strong cry, and had a developmentally appropriate gross neurological examination.

How does ethanol exposure in children typically occur?

Recent reports from the American Association of Poison Control Centers’ National Poison Data System demonstrate that ethanol exposures comprise 1% to 3% of total exposures in children aged ≤5 years.

The most common sources are ethanol-containing beverages, mouthwash, and cologne/perfume.¹ Ethanol can also be found as a solvent for certain pediatric liquid medications (eg, ranitidine) or in flavor extracts (eg, vanilla extract, orange extract). Any clear alcohol (eg, vodka, gin, rum) stored in an accessible site, such as a refrigerator, may be mistaken for water. In many reports, a caregiver unintentionally used the alcohol to reconstitute formula; however, intentional provision of alcohol to toddlers, usually as a sedative, is a recurring concern.²

What are the clinical concerns in children with ethanol intoxication?

An understanding of the pathways of ethanol metabolism frames the key issues surrounding ethanol exposure in small children. Ethanol is metabolized in the liver primarily through sequential oxidation by alcohol-dehydrogenase (ADH) and aldehyde-dehydrogenase (ALDH), which reduce nicotinamide adenine dinucleotide (NAD+) to NAD plus hydrogen (NADH) in each step. The final product of this pathway, acetate, is then converted to acetyl coenzyme A (acetyl-CoA), which enters into the Krebs cycle for thiamine-dependent metabolism to carbon dioxide and water (Figure). With substantial exposures to ethanol, the accumulation of NADH creates an imbalance in the body’s reducing potential, resulting in metabolic disturbances such as alcoholic ketoacidosis.

Under usual conditions, a normal serum glucose concentration is maintained from ingested carbohydrates and via glycogenolysis of hepatic glycogen stores. Such glycogen reserves can sustain normal blood glucose concentrations for several hours in adults but for a shorter period in children. Once glycogen is depleted, as is common after an overnight fast, glucose can be generated through gluconeogenesis.

However, in the presence of ethanol (Figure), the excessive reducing potential (ie, NADH) that results from ethanol metabolism shunts pyruvate away from the gluconeogenic pathway (toward lactate), inhibiting glucose production. Unlike adults, children and infants, who have relatively low glycogen reserves, are at significant risk for hypoglycemia following ethanol exposure. This represents the largest contributor to morbidity and mortality of children with ethanol intoxication.³ Patients with hypoglycemia can have a highly variable clinical presentation including agitation, seizures, focality, or coma.⁴

Case Continuation

Intravenous (IV) access was obtained, and the patient was placed on a dextrose-containing fluid at 1.5 times the maintenance flow rate. Pertinent laboratory studies revealed a serum glucose level of 90 mg/dL, normal electrolyte panel, and an initial blood alcohol concentration of 337 mg/dL (approximately 30 minutes postingestion).

How do children with ethanol intoxication present?

While there is some variation in clinical effects among nontolerant adults, acute ethanol intoxication with a serum concentration >250 mg/dL is frequently associated with stupor, respiratory depression, and hypotension. A concentration >400 mg/dL may be associated with coma or apnea. Although similar clinical effects are expected in adolescents and children, infants often have counterintuitive clinical findings.

To date, eight cases of significant infant ethanol exposure exist in the literature (age range, 29 days to 9 months; ethanol concentration, 183-524 mg/dL). Respiratory depression was absent in all cases.^5-9 In all but two cases, the neurological examination revealed only subtle decreases in interaction or tone. The remaining two children were described as obtunded and flaccid (ethanol levels, 405 mg/dL and 524 mg/dL, respectively) and were intubated for airway protection despite normal respiratory rates.^7,10

The incongruence between the clinical findings (both the neurological examination and respiratory effects) and the ethanol concentration is difficult to explain. It may be due to age-related neurological immaturity or a limited ability to perform the required detailed neurological examinations in children. In particular, the relatively preserved level of consciousness, despite an otherwise coma-inducing ethanol concentration, is unique to infants. Accordingly, there should be a low threshold to check ethanol concentrations in infants presenting with apparent life-threatening events, altered mental status, decreased tone, or unexplained hypoglycemia or hypothermia.

 

What is the estimated time to sobriety in infants?

Ethanol is eliminated via a hepatic enzymatic oxidation pathway that becomes saturated at low serum levels. In nontolerant adults, this results in a zero-order kinetic elimination pattern with an ethanol elimination rate of approximately 20 mg/dL per hour. Anecdotally, it had been thought that children clear ethanol at roughly double this rate via unclear mechanisms. However, a review of published kinetic data suggests the actual rate of clearance may not differ substantially from adults (range, 19-34 mg/dL per hour).^5-7,10,11

Case Conclusion

The patient was transferred to a tertiary care pediatric hospital for continued management, where the markedly elevated serum ethanol concentration was confirmed.  She was maintained on a dextrose-containing IV fluid and observed overnight without development of any complications. Serial serum ethanol concentrations were performed and complete clearance was achieved approximately 20 hours postingestion, suggesting a metabolic rate of 16 mg/dL per hour. The infant was discharged home with supervision by child protective services.

Dr Boroughf is a toxicology fellow, department of emergency medicine, Albert Einstein Medical Center, Philadelphia, Pennsylvania. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board. Dr Henretig is an attending toxicologist, department of emergency medicine, Children’s Hospital of Philadelphia, Pennsylvania.

Case

A previously healthy 4-month-old girl was brought into the ED for concerns of alcohol ingestion. Reportedly, the infant’s father reconstituted 4 ounces of powdered formula using what he thought was water from an unmarked bottle in his refrigerator. He later realized that the bottle contained rum, although he still let the child finish the 4 ounces of formula in the hopes that she would vomit—which did not occur.

Upon arrival to the ED, the infant’s vital signs were: blood pressure, 100/61 mm Hg; heart rate, 155 beats/minute; respiratory rate, 36 breaths/minute; and temperature, normal. Oxygen saturation was 98% on room air. A rapid bedside blood glucose test was 89 mg/dL. The infant’s physical examination was unremarkable. She appeared active but hungry, had a strong cry, and had a developmentally appropriate gross neurological examination.

How does ethanol exposure in children typically occur?

Recent reports from the American Association of Poison Control Centers’ National Poison Data System demonstrate that ethanol exposures comprise 1% to 3% of total exposures in children aged ≤5 years.

The most common sources are ethanol-containing beverages, mouthwash, and cologne/perfume.¹ Ethanol can also be found as a solvent for certain pediatric liquid medications (eg, ranitidine) or in flavor extracts (eg, vanilla extract, orange extract). Any clear alcohol (eg, vodka, gin, rum) stored in an accessible site, such as a refrigerator, may be mistaken for water. In many reports, a caregiver unintentionally used the alcohol to reconstitute formula; however, intentional provision of alcohol to toddlers, usually as a sedative, is a recurring concern.²

What are the clinical concerns in children with ethanol intoxication?

An understanding of the pathways of ethanol metabolism frames the key issues surrounding ethanol exposure in small children. Ethanol is metabolized in the liver primarily through sequential oxidation by alcohol-dehydrogenase (ADH) and aldehyde-dehydrogenase (ALDH), which reduce nicotinamide adenine dinucleotide (NAD+) to NAD plus hydrogen (NADH) in each step. The final product of this pathway, acetate, is then converted to acetyl coenzyme A (acetyl-CoA), which enters into the Krebs cycle for thiamine-dependent metabolism to carbon dioxide and water (Figure). With substantial exposures to ethanol, the accumulation of NADH creates an imbalance in the body’s reducing potential, resulting in metabolic disturbances such as alcoholic ketoacidosis.

Under usual conditions, a normal serum glucose concentration is maintained from ingested carbohydrates and via glycogenolysis of hepatic glycogen stores. Such glycogen reserves can sustain normal blood glucose concentrations for several hours in adults but for a shorter period in children. Once glycogen is depleted, as is common after an overnight fast, glucose can be generated through gluconeogenesis.

However, in the presence of ethanol (Figure), the excessive reducing potential (ie, NADH) that results from ethanol metabolism shunts pyruvate away from the gluconeogenic pathway (toward lactate), inhibiting glucose production. Unlike adults, children and infants, who have relatively low glycogen reserves, are at significant risk for hypoglycemia following ethanol exposure. This represents the largest contributor to morbidity and mortality of children with ethanol intoxication.³ Patients with hypoglycemia can have a highly variable clinical presentation including agitation, seizures, focality, or coma.⁴

Case Continuation

Intravenous (IV) access was obtained, and the patient was placed on a dextrose-containing fluid at 1.5 times the maintenance flow rate. Pertinent laboratory studies revealed a serum glucose level of 90 mg/dL, normal electrolyte panel, and an initial blood alcohol concentration of 337 mg/dL (approximately 30 minutes postingestion).

How do children with ethanol intoxication present?

While there is some variation in clinical effects among nontolerant adults, acute ethanol intoxication with a serum concentration >250 mg/dL is frequently associated with stupor, respiratory depression, and hypotension. A concentration >400 mg/dL may be associated with coma or apnea. Although similar clinical effects are expected in adolescents and children, infants often have counterintuitive clinical findings.

To date, eight cases of significant infant ethanol exposure exist in the literature (age range, 29 days to 9 months; ethanol concentration, 183-524 mg/dL). Respiratory depression was absent in all cases.^5-9 In all but two cases, the neurological examination revealed only subtle decreases in interaction or tone. The remaining two children were described as obtunded and flaccid (ethanol levels, 405 mg/dL and 524 mg/dL, respectively) and were intubated for airway protection despite normal respiratory rates.^7,10

The incongruence between the clinical findings (both the neurological examination and respiratory effects) and the ethanol concentration is difficult to explain. It may be due to age-related neurological immaturity or a limited ability to perform the required detailed neurological examinations in children. In particular, the relatively preserved level of consciousness, despite an otherwise coma-inducing ethanol concentration, is unique to infants. Accordingly, there should be a low threshold to check ethanol concentrations in infants presenting with apparent life-threatening events, altered mental status, decreased tone, or unexplained hypoglycemia or hypothermia.

 

What is the estimated time to sobriety in infants?

Ethanol is eliminated via a hepatic enzymatic oxidation pathway that becomes saturated at low serum levels. In nontolerant adults, this results in a zero-order kinetic elimination pattern with an ethanol elimination rate of approximately 20 mg/dL per hour. Anecdotally, it had been thought that children clear ethanol at roughly double this rate via unclear mechanisms. However, a review of published kinetic data suggests the actual rate of clearance may not differ substantially from adults (range, 19-34 mg/dL per hour).^5-7,10,11

Case Conclusion

The patient was transferred to a tertiary care pediatric hospital for continued management, where the markedly elevated serum ethanol concentration was confirmed.  She was maintained on a dextrose-containing IV fluid and observed overnight without development of any complications. Serial serum ethanol concentrations were performed and complete clearance was achieved approximately 20 hours postingestion, suggesting a metabolic rate of 16 mg/dL per hour. The infant was discharged home with supervision by child protective services.

Dr Boroughf is a toxicology fellow, department of emergency medicine, Albert Einstein Medical Center, Philadelphia, Pennsylvania. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board. Dr Henretig is an attending toxicologist, department of emergency medicine, Children’s Hospital of Philadelphia, Pennsylvania.

Case

A previously healthy 4-month-old girl was brought into the ED for concerns of alcohol ingestion. Reportedly, the infant’s father reconstituted 4 ounces of powdered formula using what he thought was water from an unmarked bottle in his refrigerator. He later realized that the bottle contained rum, although he still let the child finish the 4 ounces of formula in the hopes that she would vomit—which did not occur.

Upon arrival to the ED, the infant’s vital signs were: blood pressure, 100/61 mm Hg; heart rate, 155 beats/minute; respiratory rate, 36 breaths/minute; and temperature, normal. Oxygen saturation was 98% on room air. A rapid bedside blood glucose test was 89 mg/dL. The infant’s physical examination was unremarkable. She appeared active but hungry, had a strong cry, and had a developmentally appropriate gross neurological examination.

How does ethanol exposure in children typically occur?

Recent reports from the American Association of Poison Control Centers’ National Poison Data System demonstrate that ethanol exposures comprise 1% to 3% of total exposures in children aged ≤5 years.

The most common sources are ethanol-containing beverages, mouthwash, and cologne/perfume.¹ Ethanol can also be found as a solvent for certain pediatric liquid medications (eg, ranitidine) or in flavor extracts (eg, vanilla extract, orange extract). Any clear alcohol (eg, vodka, gin, rum) stored in an accessible site, such as a refrigerator, may be mistaken for water. In many reports, a caregiver unintentionally used the alcohol to reconstitute formula; however, intentional provision of alcohol to toddlers, usually as a sedative, is a recurring concern.²

What are the clinical concerns in children with ethanol intoxication?

An understanding of the pathways of ethanol metabolism frames the key issues surrounding ethanol exposure in small children. Ethanol is metabolized in the liver primarily through sequential oxidation by alcohol-dehydrogenase (ADH) and aldehyde-dehydrogenase (ALDH), which reduce nicotinamide adenine dinucleotide (NAD+) to NAD plus hydrogen (NADH) in each step. The final product of this pathway, acetate, is then converted to acetyl coenzyme A (acetyl-CoA), which enters into the Krebs cycle for thiamine-dependent metabolism to carbon dioxide and water (Figure). With substantial exposures to ethanol, the accumulation of NADH creates an imbalance in the body’s reducing potential, resulting in metabolic disturbances such as alcoholic ketoacidosis.

Under usual conditions, a normal serum glucose concentration is maintained from ingested carbohydrates and via glycogenolysis of hepatic glycogen stores. Such glycogen reserves can sustain normal blood glucose concentrations for several hours in adults but for a shorter period in children. Once glycogen is depleted, as is common after an overnight fast, glucose can be generated through gluconeogenesis.

However, in the presence of ethanol (Figure), the excessive reducing potential (ie, NADH) that results from ethanol metabolism shunts pyruvate away from the gluconeogenic pathway (toward lactate), inhibiting glucose production. Unlike adults, children and infants, who have relatively low glycogen reserves, are at significant risk for hypoglycemia following ethanol exposure. This represents the largest contributor to morbidity and mortality of children with ethanol intoxication.³ Patients with hypoglycemia can have a highly variable clinical presentation including agitation, seizures, focality, or coma.⁴

Case Continuation

Intravenous (IV) access was obtained, and the patient was placed on a dextrose-containing fluid at 1.5 times the maintenance flow rate. Pertinent laboratory studies revealed a serum glucose level of 90 mg/dL, normal electrolyte panel, and an initial blood alcohol concentration of 337 mg/dL (approximately 30 minutes postingestion).

How do children with ethanol intoxication present?

While there is some variation in clinical effects among nontolerant adults, acute ethanol intoxication with a serum concentration >250 mg/dL is frequently associated with stupor, respiratory depression, and hypotension. A concentration >400 mg/dL may be associated with coma or apnea. Although similar clinical effects are expected in adolescents and children, infants often have counterintuitive clinical findings.

To date, eight cases of significant infant ethanol exposure exist in the literature (age range, 29 days to 9 months; ethanol concentration, 183-524 mg/dL). Respiratory depression was absent in all cases.^5-9 In all but two cases, the neurological examination revealed only subtle decreases in interaction or tone. The remaining two children were described as obtunded and flaccid (ethanol levels, 405 mg/dL and 524 mg/dL, respectively) and were intubated for airway protection despite normal respiratory rates.^7,10

The incongruence between the clinical findings (both the neurological examination and respiratory effects) and the ethanol concentration is difficult to explain. It may be due to age-related neurological immaturity or a limited ability to perform the required detailed neurological examinations in children. In particular, the relatively preserved level of consciousness, despite an otherwise coma-inducing ethanol concentration, is unique to infants. Accordingly, there should be a low threshold to check ethanol concentrations in infants presenting with apparent life-threatening events, altered mental status, decreased tone, or unexplained hypoglycemia or hypothermia.

 

What is the estimated time to sobriety in infants?

Ethanol is eliminated via a hepatic enzymatic oxidation pathway that becomes saturated at low serum levels. In nontolerant adults, this results in a zero-order kinetic elimination pattern with an ethanol elimination rate of approximately 20 mg/dL per hour. Anecdotally, it had been thought that children clear ethanol at roughly double this rate via unclear mechanisms. However, a review of published kinetic data suggests the actual rate of clearance may not differ substantially from adults (range, 19-34 mg/dL per hour).^5-7,10,11

Case Conclusion

The patient was transferred to a tertiary care pediatric hospital for continued management, where the markedly elevated serum ethanol concentration was confirmed.  She was maintained on a dextrose-containing IV fluid and observed overnight without development of any complications. Serial serum ethanol concentrations were performed and complete clearance was achieved approximately 20 hours postingestion, suggesting a metabolic rate of 16 mg/dL per hour. The infant was discharged home with supervision by child protective services.

Dr Boroughf is a toxicology fellow, department of emergency medicine, Albert Einstein Medical Center, Philadelphia, Pennsylvania. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board. Dr Henretig is an attending toxicologist, department of emergency medicine, Children’s Hospital of Philadelphia, Pennsylvania.

The extensor mechanism of the knee comprises the quadriceps tendon, the patella, and the patellar tendon. The extensor mechanism may be damaged by injury to these structures, with consequences such as the inability to actively extend the knee and hemarthrosis.^1,2 Disruption of this mechanism is rare, and the most common injury pattern is an eccentric contraction of the quadriceps tendon on a flexed knee causing a tendon (quadriceps or patellar) rupture or a patella fracture.^1,2

Patellar tendon ruptures are more common in persons younger than 40 years.¹ Treatment is surgical, regardless of age and physical activity. In the acute setting, repair can be end-to-end suture or transosseous tunnel insertion. End-to-end suturing is difficult in chronic patellar tendon ruptures because of patella alta secondary to quadriceps contraction.³ Treatment options for chronic ruptures may involve transpatellar traction⁴ or tendon reinforcement with fascia lata, a semitendinosus band, or synthetic materials.^3-5 Alternatively, tendon autograft and allografts have also been recommended, especially in extreme situations.^1,6 Furthermore, animal experiments have shown that a compact platelet-rich fibrin scaffold (CPFS) has the potential to accelerate healing of patellar tendon defects and to act as a bioscaffold for graft augmentation.⁷

We describe the case of a 30-year-old man who underwent extensor mechanism reconstruction with cadaveric tendon–patellar tendon–bone allograft for failure of an infected primary end-to-end repair. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 30-year-old healthy man landed on an empty glass fish tank, resulting in a traumatic right-knee arthrotomy. On initial evaluation, the patient had a negative straight-leg-raise test and impaired knee extension. The patient was taken urgently to the operating room for irrigation and débridement and concurrent repair of the patellar tendon laceration. Antibiotic prophylaxis with 2 g of intravenous (IV) cefazolin was given in the emergency room.

Intraoperatively, after visualizing the patellar tendon laceration and excluding any associated chondral lesions, we proceeded with extensive débridement and irrigation using 9 L of normal saline pulse lavage. After we achieved a clean site, we proceeded to repair the patellar tendon using No. 2 FiberWire sutures (Arthrex, Naples, Florida) with a classic Krackow repair⁸ consisting of 2 sutures run in a 4-row fashion through the patella and the patellar tendon. The suture was securely tightened and then tested for stability to at least 90° of knee flexion. The retinaculum was repaired using No. 0 Vicryl sutures (Ethicon, Somerville, New Jersey). After wound closure and dressing, the patient was placed in a hinged knee brace locked in extension at all times after surgery. Antibiotic treatment with IV cefazolin was administered for 48 hours.

Postoperative management consisted of weight-bearing as tolerated on the operative limb and appropriate deep venous thrombosis prophylaxis. The patient followed up in clinic 2 weeks and 4 weeks after surgery. At 4 weeks, the patient was noted to have a secondary wound infection with superficial dehiscence and serosanguineous drainage. No wound opening was noticed, and local wound care was performed with a 1-week course of oral cephalexin. The patient was scheduled to follow up a few weeks later but did not follow up for a year.

At 1-year follow-up, the patient reported that he had had a steady progression of his knee range of motion (ROM) with decreased pain. However, over time, the patient noted subjective instability of the knee, with frequent falls occurring close to his 1-year follow-up. Examination of his knee showed that his active ROM ranged from 20° in extension to 120° in flexion, with a weak extensor mechanism. Passively, his knee could be brought to full extension. His incision was well healed, but it had an area of bogginess in the middle. Radiographs showed patella alta on the affected knee, with a lengthening of the patellar tendon of 7.70 cm on the right compared with 5.18 cm on the left. Magnetic resonance imaging (MRI) showed moderate-to-severe patellar tendinosis with small fluid pockets around the surgical material and evidence of acute patellar enthesopathy. The laboratory values showed a white blood cell count of 7580/μL (normal, 4500-11,000/μL), an erythrocyte sedimentation rate of 2 mm/h (normal, 1-15 mm/h), and a C-reactive protein level of 1.93 mg/dL (normal, 0.00-0.29 mg/dL). Based on the clinical examination and imaging findings, there was a concern for a possible chronic deep-tissue infection, in addition to failure of the primary patellar tendon repair. Operative versus nonoperative management options were discussed with the patient, and he elected to undergo surgery.

During surgery, the patellar laxity was confirmed, and the patellar tendon was noticed to be chronically thickened and surrounded by unhealthy tissue. Initially, an extensive soft-tissue débridement was performed, and all patellar tendon loculations visualized on the preoperative MRI were drained; a solid purulent-like fluid was expressed. Unfortunately, the extensive and required débridement did not allow the preservation of the patellar tendon. Appropriate cultures were taken and sent for immediate Gram-stain analysis, which returned negative. Tissue samples from the patellar tendon were also sent to the pathology department for analysis. Intraoperatively, the infrapatellar defect was filled temporarily with a tobramycin cement spacer mixed with 2 g of vancomycin in a manner similar to that of the Masquelet technique used for infected long-bone nonunions with bone loss.^9,10 This technique is a 2-stage procedure that promotes the formation of a biologic membrane that allows bone healing in the reconstruction of long-bone defects. The first stage consists of a radical débridement with soft-tissue repair by flaps when needed, with the insertion of a polymethylmethacrylate cement spacer into the bone defect. The second stage is usually performed 6 to 8 weeks later, with removal of the spacer and preservation of the induced membrane, which is filled with iliac crest bone autograft augmented (if necessary) with demineralized allograft.

 

The incision was closed primarily, and after surgery, the patient was allowed to bear weight as tolerated in a hinged knee brace locked in extension. Final laboratory analysis from cultures and tissue samples revealed acute and chronic inflammation with more than 20 neutrophils per high-powered field. No organisms grew from aerobic, anaerobic, fungal, or mycobacterial cultures. The infectious disease service was consulted and recommended oral cephalexin.

Because all cultures were negative, all laboratory examinations did not indicate any residual infections, and no bony involvement was noticed intraoperatively or in the preoperative knee MRI, we decided to proceed with the second stage of the Masquelet technique after 2 weeks. The patient returned to the operating room for final reconstruction of his patellar tendon using a custom-ordered cadaveric tendon–patellar tendon–bone allograft, the length of which was determined by measuring the contralateral patellar tendon, ie, 5.18 cm (Figure 1A). The previous anterior knee incision was reopened and extended distally past the tibial tuberosity and proximally toward the quadriceps tendon. The antibiotic spacer was removed. We proceeded with a repeat irrigation and débridement and the allograft transfer. The selected allograft was customized by reducing the tibial bone component to an approximately 1×2-cm bone block and by reducing the allograft patellar thickness with an oscillating saw, leaving an approximately 2-mm thick patellar bone graft attached to the patellar tendon. In a similar technique using an oscillating saw, we shaved off the anterior cortex of the patient’s patella to accommodate, in a sandwich fashion, the patellar allograft. Proximally, the quadriceps tendon insertion was split longitudinally and partially separated from the superior pole of the patellar tendon to allow seating and fixation of the modified quadriceps allograft tendon component.

We proceeded with the fixation of the allograft first distally on the patella. The anterior cortex of the tibial tuberosity was resected to allow the perfect seating of the bone block allograft. The graft was secured with a 4.0-mm fully threaded cancellous lag screw and reinforced with a 2.4-mm, 3-hole T-volar buttress plate (Synthes, Paoli, Pennsylvania). The plate was contoured to better fit the patient’s tibia. We sutured the patellar allograft tendon to the patella using two No. 2-0 FiberWire sutures in Krackow suture technique⁸ (Figures 1B, 1C). We obtained good fixation of the patellar tendon, and the distance between the patellar insertion and the inferior patellar pole was the same as before surgery: 5.57 cm and comparable to the contralateral side (Figures 2A-2C). The patellar allograft and autograft sandwich were secured with additional No. 2-0 FiberWire sutures, and the quadriceps allograft and autograft were secured with the cross-stitch technique with the same material. Fine suturing of the quadriceps tendon was done with No. 0 Vicryl sutures. After the fixation was completed, we tested the stability of the reconstruction and found good flexion up to 120°.

The postoperative protocol consisted of weight-bearing as tolerated in full extension and passive knee ROM, using a continuous passive ROM machine from 0° to 45° for the first 4 weeks, followed by active ROM, increased as tolerated, during the next 8 weeks.

The patient was seen in clinic 3 and 9 months after surgery. At the 3-month follow-up appointment, the patient’s examination showed knee ROM from 0° extension to 130° of flexion, no secondary infection signs, and radiographic evidence of a well-healing patellar allograft with symmetric patellar tendon length to the contralateral side. At 9-month follow-up, the patient’s active ROM was from 0° extension to 140° flexion (Figures 3A, 3B), and he had returned to his preinjury level of functioning.

Discussion

This case report describes the successful reconstruction of a patellar tendon defect with cadaveric tendon–patellar tendon–bone allograft. Extensor mechanism injuries are uncommon in general, and the incidence of patellar tendon injury is higher in men than in women.² Patellar tendon tears occur frequently in active patients younger than 40 years, usually as a result of sudden quadriceps contraction with the knee slightly flexed.¹ Treatment of patellar tendon injury is surgical, and functional outcomes for patients with this injury are equivalent to those of patients with quadriceps tendon injuries or patellar fractures.² Acute patellar tendon tears can be repaired by end-to-end suturing or transosseous tunnel insertion in the tibia or patella.¹ Reinforcement is often added between the patella and tibial tuberosity, using a semitendinosus band or wire.¹ End-to-end suture is performed using a thick resorbable suture. It is important to avoid patella alta during suturing, comparing the position of the patella with the contralateral patella with the knee in 45° of flexion. In proximal avulsion, the tendon is anchored to the bone by 2 thick nonresorbable sutures through 2 parallel bone tunnels to the proximal pole of the patella. Distal avulsion is rare in adults, but it can be managed by using staples or suture anchors.¹

 

End-to-end suturing of chronic patellar tendon defects is difficult more than 45 days after injury primarily because of difficulties in correcting patella alta secondary to the upward force exerted by the quadriceps tendon.^1,3 Extreme situations similar to the case we present warrant Achilles or patellar tendon allograft for reconstruction of the extensor mechanism.^1,3,6,9

Extensor mechanism allograft also provides an effective remedy for severe quadriceps deficiency caused by loss of the patella, patellar tendon, and quadriceps tendon in total knee arthroplasty.¹⁰ However, in such cases, late failure is common, and major quadriceps deficiency occurs after removal of the allograft material.¹⁰ To improve outcome, a novel technique using the medial gastrocnemius muscle transferred to the muscular portion of the vastus medialis and lateralis flaps provides a secure and strong closure of the anterior knee, thereby restoring the extensor mechanism of the knee.¹⁰

Patellar tendon reconstruction with allograft tissue has been successfully used, especially in cases related to chronic patellar tendon ruptures¹¹ and total knee arthroplasty.^6,12-14 Crossett and colleagues¹² showed that, at 2-year follow-up, the average knee score for pain, ROM, and stability had improved from 26 points (range, 6-39 points) before surgery to 81 points (range, 40-92 points). The average knee score for function had also improved: 14 points (range, 0-35 points) before surgery to 53 points (range, 30-90 points).¹² Primary repair may succeed in early intervention, but in an established rupture, allograft reconstruction is often necessary. Achilles tendon is the preferred allograft, with the calcaneus fragment embedded into the proximal tibia as a new tubercle and the tendon sutured into the remaining extensor mechanism.^1,11 The repair is further protected using a cable loop from the superior pole of the patella to a drill hole in the upper tibia.⁹ Techniques have also been described involving passage of the proximal aspect of the allograft tendon through patellar bone tunnels and suture fixation to the native quadriceps tendon.^11,15 However, in our technique, we shaved off the anterior cortex of the patient’s patella to allow a sandwich-type over-position of the allograft to secure fixation to the patella.

Another alternative to allograft reconstruction involves biocompatible scaffolds. Such scaffolds incorporate the use of platelets in a fibrin framework. A CPFS, produced from blood and calcium gluconate to improve healing of patellar tendon defects, has been described in animal studies.⁷ In the rabbit model, CPFS acts as a provisional bioscaffold that can accelerate healing of an injured patellar tendon repair, potentially secondary to several growth factors derived from platelets.⁷ Platelets are biocompatible sources of growth factors, and CPFS can act as a scaffold to restore the mechanical integrity of injured soft tissue.^7,16 In addition, CPFS can act to lower donor-site morbidity associated with harvesting tissue autograft.⁷ However, to our knowledge, such scaffolds have not been used in human trials. The LARS biocompatible ligament (Corin Group PLC, Cirencester, United Kingdom), currently not approved by the US Food and Drug Administration, is used for reconstructions of isolated or multiple knee ligament injuries.¹⁷ This graft requires the presence of healthy tissue with good blood supply from which new tendon or ligament can grow in. Sometimes it is also used for extensor mechanism reconstruction after radical tumor resection around the knee; however, good results are achieved in only 59% of cases,¹⁸ and to our knowledge, only 1 case of primary repair of a patellar tendon rupture has been published.¹⁹

Techniques involving the use of tendon–patellar tendon–bone graft with fixation via the sandwich-type over-position of the allograft for chronic patellar tendon rupture have not been described in the literature. In our patient, given the extensive patellar tendon lesion and inflammation with chronic tissue degeneration, there was no option but to use allograft. To improve the patient’s outcome, we chose the strongest possible allograft, tendon–patellar tendon–bone graft.

Conclusion

Revision patellar tendon reconstruction is a challenging, but necessary, procedure to restore the extensor mechanism of the knee, especially in young, active individuals. Various options to reconstruct the tissue defects are available. Our patient was successfully treated with a tendon–patellar tendon–bone allograft reconstruction.

The extensor mechanism of the knee comprises the quadriceps tendon, the patella, and the patellar tendon. The extensor mechanism may be damaged by injury to these structures, with consequences such as the inability to actively extend the knee and hemarthrosis.^1,2 Disruption of this mechanism is rare, and the most common injury pattern is an eccentric contraction of the quadriceps tendon on a flexed knee causing a tendon (quadriceps or patellar) rupture or a patella fracture.^1,2

Patellar tendon ruptures are more common in persons younger than 40 years.¹ Treatment is surgical, regardless of age and physical activity. In the acute setting, repair can be end-to-end suture or transosseous tunnel insertion. End-to-end suturing is difficult in chronic patellar tendon ruptures because of patella alta secondary to quadriceps contraction.³ Treatment options for chronic ruptures may involve transpatellar traction⁴ or tendon reinforcement with fascia lata, a semitendinosus band, or synthetic materials.^3-5 Alternatively, tendon autograft and allografts have also been recommended, especially in extreme situations.^1,6 Furthermore, animal experiments have shown that a compact platelet-rich fibrin scaffold (CPFS) has the potential to accelerate healing of patellar tendon defects and to act as a bioscaffold for graft augmentation.⁷

We describe the case of a 30-year-old man who underwent extensor mechanism reconstruction with cadaveric tendon–patellar tendon–bone allograft for failure of an infected primary end-to-end repair. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 30-year-old healthy man landed on an empty glass fish tank, resulting in a traumatic right-knee arthrotomy. On initial evaluation, the patient had a negative straight-leg-raise test and impaired knee extension. The patient was taken urgently to the operating room for irrigation and débridement and concurrent repair of the patellar tendon laceration. Antibiotic prophylaxis with 2 g of intravenous (IV) cefazolin was given in the emergency room.

Intraoperatively, after visualizing the patellar tendon laceration and excluding any associated chondral lesions, we proceeded with extensive débridement and irrigation using 9 L of normal saline pulse lavage. After we achieved a clean site, we proceeded to repair the patellar tendon using No. 2 FiberWire sutures (Arthrex, Naples, Florida) with a classic Krackow repair⁸ consisting of 2 sutures run in a 4-row fashion through the patella and the patellar tendon. The suture was securely tightened and then tested for stability to at least 90° of knee flexion. The retinaculum was repaired using No. 0 Vicryl sutures (Ethicon, Somerville, New Jersey). After wound closure and dressing, the patient was placed in a hinged knee brace locked in extension at all times after surgery. Antibiotic treatment with IV cefazolin was administered for 48 hours.

Postoperative management consisted of weight-bearing as tolerated on the operative limb and appropriate deep venous thrombosis prophylaxis. The patient followed up in clinic 2 weeks and 4 weeks after surgery. At 4 weeks, the patient was noted to have a secondary wound infection with superficial dehiscence and serosanguineous drainage. No wound opening was noticed, and local wound care was performed with a 1-week course of oral cephalexin. The patient was scheduled to follow up a few weeks later but did not follow up for a year.

At 1-year follow-up, the patient reported that he had had a steady progression of his knee range of motion (ROM) with decreased pain. However, over time, the patient noted subjective instability of the knee, with frequent falls occurring close to his 1-year follow-up. Examination of his knee showed that his active ROM ranged from 20° in extension to 120° in flexion, with a weak extensor mechanism. Passively, his knee could be brought to full extension. His incision was well healed, but it had an area of bogginess in the middle. Radiographs showed patella alta on the affected knee, with a lengthening of the patellar tendon of 7.70 cm on the right compared with 5.18 cm on the left. Magnetic resonance imaging (MRI) showed moderate-to-severe patellar tendinosis with small fluid pockets around the surgical material and evidence of acute patellar enthesopathy. The laboratory values showed a white blood cell count of 7580/μL (normal, 4500-11,000/μL), an erythrocyte sedimentation rate of 2 mm/h (normal, 1-15 mm/h), and a C-reactive protein level of 1.93 mg/dL (normal, 0.00-0.29 mg/dL). Based on the clinical examination and imaging findings, there was a concern for a possible chronic deep-tissue infection, in addition to failure of the primary patellar tendon repair. Operative versus nonoperative management options were discussed with the patient, and he elected to undergo surgery.

During surgery, the patellar laxity was confirmed, and the patellar tendon was noticed to be chronically thickened and surrounded by unhealthy tissue. Initially, an extensive soft-tissue débridement was performed, and all patellar tendon loculations visualized on the preoperative MRI were drained; a solid purulent-like fluid was expressed. Unfortunately, the extensive and required débridement did not allow the preservation of the patellar tendon. Appropriate cultures were taken and sent for immediate Gram-stain analysis, which returned negative. Tissue samples from the patellar tendon were also sent to the pathology department for analysis. Intraoperatively, the infrapatellar defect was filled temporarily with a tobramycin cement spacer mixed with 2 g of vancomycin in a manner similar to that of the Masquelet technique used for infected long-bone nonunions with bone loss.^9,10 This technique is a 2-stage procedure that promotes the formation of a biologic membrane that allows bone healing in the reconstruction of long-bone defects. The first stage consists of a radical débridement with soft-tissue repair by flaps when needed, with the insertion of a polymethylmethacrylate cement spacer into the bone defect. The second stage is usually performed 6 to 8 weeks later, with removal of the spacer and preservation of the induced membrane, which is filled with iliac crest bone autograft augmented (if necessary) with demineralized allograft.

 

The incision was closed primarily, and after surgery, the patient was allowed to bear weight as tolerated in a hinged knee brace locked in extension. Final laboratory analysis from cultures and tissue samples revealed acute and chronic inflammation with more than 20 neutrophils per high-powered field. No organisms grew from aerobic, anaerobic, fungal, or mycobacterial cultures. The infectious disease service was consulted and recommended oral cephalexin.

Because all cultures were negative, all laboratory examinations did not indicate any residual infections, and no bony involvement was noticed intraoperatively or in the preoperative knee MRI, we decided to proceed with the second stage of the Masquelet technique after 2 weeks. The patient returned to the operating room for final reconstruction of his patellar tendon using a custom-ordered cadaveric tendon–patellar tendon–bone allograft, the length of which was determined by measuring the contralateral patellar tendon, ie, 5.18 cm (Figure 1A). The previous anterior knee incision was reopened and extended distally past the tibial tuberosity and proximally toward the quadriceps tendon. The antibiotic spacer was removed. We proceeded with a repeat irrigation and débridement and the allograft transfer. The selected allograft was customized by reducing the tibial bone component to an approximately 1×2-cm bone block and by reducing the allograft patellar thickness with an oscillating saw, leaving an approximately 2-mm thick patellar bone graft attached to the patellar tendon. In a similar technique using an oscillating saw, we shaved off the anterior cortex of the patient’s patella to accommodate, in a sandwich fashion, the patellar allograft. Proximally, the quadriceps tendon insertion was split longitudinally and partially separated from the superior pole of the patellar tendon to allow seating and fixation of the modified quadriceps allograft tendon component.

We proceeded with the fixation of the allograft first distally on the patella. The anterior cortex of the tibial tuberosity was resected to allow the perfect seating of the bone block allograft. The graft was secured with a 4.0-mm fully threaded cancellous lag screw and reinforced with a 2.4-mm, 3-hole T-volar buttress plate (Synthes, Paoli, Pennsylvania). The plate was contoured to better fit the patient’s tibia. We sutured the patellar allograft tendon to the patella using two No. 2-0 FiberWire sutures in Krackow suture technique⁸ (Figures 1B, 1C). We obtained good fixation of the patellar tendon, and the distance between the patellar insertion and the inferior patellar pole was the same as before surgery: 5.57 cm and comparable to the contralateral side (Figures 2A-2C). The patellar allograft and autograft sandwich were secured with additional No. 2-0 FiberWire sutures, and the quadriceps allograft and autograft were secured with the cross-stitch technique with the same material. Fine suturing of the quadriceps tendon was done with No. 0 Vicryl sutures. After the fixation was completed, we tested the stability of the reconstruction and found good flexion up to 120°.

The postoperative protocol consisted of weight-bearing as tolerated in full extension and passive knee ROM, using a continuous passive ROM machine from 0° to 45° for the first 4 weeks, followed by active ROM, increased as tolerated, during the next 8 weeks.

The patient was seen in clinic 3 and 9 months after surgery. At the 3-month follow-up appointment, the patient’s examination showed knee ROM from 0° extension to 130° of flexion, no secondary infection signs, and radiographic evidence of a well-healing patellar allograft with symmetric patellar tendon length to the contralateral side. At 9-month follow-up, the patient’s active ROM was from 0° extension to 140° flexion (Figures 3A, 3B), and he had returned to his preinjury level of functioning.

Discussion

This case report describes the successful reconstruction of a patellar tendon defect with cadaveric tendon–patellar tendon–bone allograft. Extensor mechanism injuries are uncommon in general, and the incidence of patellar tendon injury is higher in men than in women.² Patellar tendon tears occur frequently in active patients younger than 40 years, usually as a result of sudden quadriceps contraction with the knee slightly flexed.¹ Treatment of patellar tendon injury is surgical, and functional outcomes for patients with this injury are equivalent to those of patients with quadriceps tendon injuries or patellar fractures.² Acute patellar tendon tears can be repaired by end-to-end suturing or transosseous tunnel insertion in the tibia or patella.¹ Reinforcement is often added between the patella and tibial tuberosity, using a semitendinosus band or wire.¹ End-to-end suture is performed using a thick resorbable suture. It is important to avoid patella alta during suturing, comparing the position of the patella with the contralateral patella with the knee in 45° of flexion. In proximal avulsion, the tendon is anchored to the bone by 2 thick nonresorbable sutures through 2 parallel bone tunnels to the proximal pole of the patella. Distal avulsion is rare in adults, but it can be managed by using staples or suture anchors.¹

 

End-to-end suturing of chronic patellar tendon defects is difficult more than 45 days after injury primarily because of difficulties in correcting patella alta secondary to the upward force exerted by the quadriceps tendon.^1,3 Extreme situations similar to the case we present warrant Achilles or patellar tendon allograft for reconstruction of the extensor mechanism.^1,3,6,9

Extensor mechanism allograft also provides an effective remedy for severe quadriceps deficiency caused by loss of the patella, patellar tendon, and quadriceps tendon in total knee arthroplasty.¹⁰ However, in such cases, late failure is common, and major quadriceps deficiency occurs after removal of the allograft material.¹⁰ To improve outcome, a novel technique using the medial gastrocnemius muscle transferred to the muscular portion of the vastus medialis and lateralis flaps provides a secure and strong closure of the anterior knee, thereby restoring the extensor mechanism of the knee.¹⁰

Patellar tendon reconstruction with allograft tissue has been successfully used, especially in cases related to chronic patellar tendon ruptures¹¹ and total knee arthroplasty.^6,12-14 Crossett and colleagues¹² showed that, at 2-year follow-up, the average knee score for pain, ROM, and stability had improved from 26 points (range, 6-39 points) before surgery to 81 points (range, 40-92 points). The average knee score for function had also improved: 14 points (range, 0-35 points) before surgery to 53 points (range, 30-90 points).¹² Primary repair may succeed in early intervention, but in an established rupture, allograft reconstruction is often necessary. Achilles tendon is the preferred allograft, with the calcaneus fragment embedded into the proximal tibia as a new tubercle and the tendon sutured into the remaining extensor mechanism.^1,11 The repair is further protected using a cable loop from the superior pole of the patella to a drill hole in the upper tibia.⁹ Techniques have also been described involving passage of the proximal aspect of the allograft tendon through patellar bone tunnels and suture fixation to the native quadriceps tendon.^11,15 However, in our technique, we shaved off the anterior cortex of the patient’s patella to allow a sandwich-type over-position of the allograft to secure fixation to the patella.

Another alternative to allograft reconstruction involves biocompatible scaffolds. Such scaffolds incorporate the use of platelets in a fibrin framework. A CPFS, produced from blood and calcium gluconate to improve healing of patellar tendon defects, has been described in animal studies.⁷ In the rabbit model, CPFS acts as a provisional bioscaffold that can accelerate healing of an injured patellar tendon repair, potentially secondary to several growth factors derived from platelets.⁷ Platelets are biocompatible sources of growth factors, and CPFS can act as a scaffold to restore the mechanical integrity of injured soft tissue.^7,16 In addition, CPFS can act to lower donor-site morbidity associated with harvesting tissue autograft.⁷ However, to our knowledge, such scaffolds have not been used in human trials. The LARS biocompatible ligament (Corin Group PLC, Cirencester, United Kingdom), currently not approved by the US Food and Drug Administration, is used for reconstructions of isolated or multiple knee ligament injuries.¹⁷ This graft requires the presence of healthy tissue with good blood supply from which new tendon or ligament can grow in. Sometimes it is also used for extensor mechanism reconstruction after radical tumor resection around the knee; however, good results are achieved in only 59% of cases,¹⁸ and to our knowledge, only 1 case of primary repair of a patellar tendon rupture has been published.¹⁹

Techniques involving the use of tendon–patellar tendon–bone graft with fixation via the sandwich-type over-position of the allograft for chronic patellar tendon rupture have not been described in the literature. In our patient, given the extensive patellar tendon lesion and inflammation with chronic tissue degeneration, there was no option but to use allograft. To improve the patient’s outcome, we chose the strongest possible allograft, tendon–patellar tendon–bone graft.

Conclusion

Revision patellar tendon reconstruction is a challenging, but necessary, procedure to restore the extensor mechanism of the knee, especially in young, active individuals. Various options to reconstruct the tissue defects are available. Our patient was successfully treated with a tendon–patellar tendon–bone allograft reconstruction.

The extensor mechanism of the knee comprises the quadriceps tendon, the patella, and the patellar tendon. The extensor mechanism may be damaged by injury to these structures, with consequences such as the inability to actively extend the knee and hemarthrosis.^1,2 Disruption of this mechanism is rare, and the most common injury pattern is an eccentric contraction of the quadriceps tendon on a flexed knee causing a tendon (quadriceps or patellar) rupture or a patella fracture.^1,2

Patellar tendon ruptures are more common in persons younger than 40 years.¹ Treatment is surgical, regardless of age and physical activity. In the acute setting, repair can be end-to-end suture or transosseous tunnel insertion. End-to-end suturing is difficult in chronic patellar tendon ruptures because of patella alta secondary to quadriceps contraction.³ Treatment options for chronic ruptures may involve transpatellar traction⁴ or tendon reinforcement with fascia lata, a semitendinosus band, or synthetic materials.^3-5 Alternatively, tendon autograft and allografts have also been recommended, especially in extreme situations.^1,6 Furthermore, animal experiments have shown that a compact platelet-rich fibrin scaffold (CPFS) has the potential to accelerate healing of patellar tendon defects and to act as a bioscaffold for graft augmentation.⁷

We describe the case of a 30-year-old man who underwent extensor mechanism reconstruction with cadaveric tendon–patellar tendon–bone allograft for failure of an infected primary end-to-end repair. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 30-year-old healthy man landed on an empty glass fish tank, resulting in a traumatic right-knee arthrotomy. On initial evaluation, the patient had a negative straight-leg-raise test and impaired knee extension. The patient was taken urgently to the operating room for irrigation and débridement and concurrent repair of the patellar tendon laceration. Antibiotic prophylaxis with 2 g of intravenous (IV) cefazolin was given in the emergency room.

Intraoperatively, after visualizing the patellar tendon laceration and excluding any associated chondral lesions, we proceeded with extensive débridement and irrigation using 9 L of normal saline pulse lavage. After we achieved a clean site, we proceeded to repair the patellar tendon using No. 2 FiberWire sutures (Arthrex, Naples, Florida) with a classic Krackow repair⁸ consisting of 2 sutures run in a 4-row fashion through the patella and the patellar tendon. The suture was securely tightened and then tested for stability to at least 90° of knee flexion. The retinaculum was repaired using No. 0 Vicryl sutures (Ethicon, Somerville, New Jersey). After wound closure and dressing, the patient was placed in a hinged knee brace locked in extension at all times after surgery. Antibiotic treatment with IV cefazolin was administered for 48 hours.

Postoperative management consisted of weight-bearing as tolerated on the operative limb and appropriate deep venous thrombosis prophylaxis. The patient followed up in clinic 2 weeks and 4 weeks after surgery. At 4 weeks, the patient was noted to have a secondary wound infection with superficial dehiscence and serosanguineous drainage. No wound opening was noticed, and local wound care was performed with a 1-week course of oral cephalexin. The patient was scheduled to follow up a few weeks later but did not follow up for a year.

At 1-year follow-up, the patient reported that he had had a steady progression of his knee range of motion (ROM) with decreased pain. However, over time, the patient noted subjective instability of the knee, with frequent falls occurring close to his 1-year follow-up. Examination of his knee showed that his active ROM ranged from 20° in extension to 120° in flexion, with a weak extensor mechanism. Passively, his knee could be brought to full extension. His incision was well healed, but it had an area of bogginess in the middle. Radiographs showed patella alta on the affected knee, with a lengthening of the patellar tendon of 7.70 cm on the right compared with 5.18 cm on the left. Magnetic resonance imaging (MRI) showed moderate-to-severe patellar tendinosis with small fluid pockets around the surgical material and evidence of acute patellar enthesopathy. The laboratory values showed a white blood cell count of 7580/μL (normal, 4500-11,000/μL), an erythrocyte sedimentation rate of 2 mm/h (normal, 1-15 mm/h), and a C-reactive protein level of 1.93 mg/dL (normal, 0.00-0.29 mg/dL). Based on the clinical examination and imaging findings, there was a concern for a possible chronic deep-tissue infection, in addition to failure of the primary patellar tendon repair. Operative versus nonoperative management options were discussed with the patient, and he elected to undergo surgery.

During surgery, the patellar laxity was confirmed, and the patellar tendon was noticed to be chronically thickened and surrounded by unhealthy tissue. Initially, an extensive soft-tissue débridement was performed, and all patellar tendon loculations visualized on the preoperative MRI were drained; a solid purulent-like fluid was expressed. Unfortunately, the extensive and required débridement did not allow the preservation of the patellar tendon. Appropriate cultures were taken and sent for immediate Gram-stain analysis, which returned negative. Tissue samples from the patellar tendon were also sent to the pathology department for analysis. Intraoperatively, the infrapatellar defect was filled temporarily with a tobramycin cement spacer mixed with 2 g of vancomycin in a manner similar to that of the Masquelet technique used for infected long-bone nonunions with bone loss.^9,10 This technique is a 2-stage procedure that promotes the formation of a biologic membrane that allows bone healing in the reconstruction of long-bone defects. The first stage consists of a radical débridement with soft-tissue repair by flaps when needed, with the insertion of a polymethylmethacrylate cement spacer into the bone defect. The second stage is usually performed 6 to 8 weeks later, with removal of the spacer and preservation of the induced membrane, which is filled with iliac crest bone autograft augmented (if necessary) with demineralized allograft.

 

The incision was closed primarily, and after surgery, the patient was allowed to bear weight as tolerated in a hinged knee brace locked in extension. Final laboratory analysis from cultures and tissue samples revealed acute and chronic inflammation with more than 20 neutrophils per high-powered field. No organisms grew from aerobic, anaerobic, fungal, or mycobacterial cultures. The infectious disease service was consulted and recommended oral cephalexin.

Because all cultures were negative, all laboratory examinations did not indicate any residual infections, and no bony involvement was noticed intraoperatively or in the preoperative knee MRI, we decided to proceed with the second stage of the Masquelet technique after 2 weeks. The patient returned to the operating room for final reconstruction of his patellar tendon using a custom-ordered cadaveric tendon–patellar tendon–bone allograft, the length of which was determined by measuring the contralateral patellar tendon, ie, 5.18 cm (Figure 1A). The previous anterior knee incision was reopened and extended distally past the tibial tuberosity and proximally toward the quadriceps tendon. The antibiotic spacer was removed. We proceeded with a repeat irrigation and débridement and the allograft transfer. The selected allograft was customized by reducing the tibial bone component to an approximately 1×2-cm bone block and by reducing the allograft patellar thickness with an oscillating saw, leaving an approximately 2-mm thick patellar bone graft attached to the patellar tendon. In a similar technique using an oscillating saw, we shaved off the anterior cortex of the patient’s patella to accommodate, in a sandwich fashion, the patellar allograft. Proximally, the quadriceps tendon insertion was split longitudinally and partially separated from the superior pole of the patellar tendon to allow seating and fixation of the modified quadriceps allograft tendon component.

We proceeded with the fixation of the allograft first distally on the patella. The anterior cortex of the tibial tuberosity was resected to allow the perfect seating of the bone block allograft. The graft was secured with a 4.0-mm fully threaded cancellous lag screw and reinforced with a 2.4-mm, 3-hole T-volar buttress plate (Synthes, Paoli, Pennsylvania). The plate was contoured to better fit the patient’s tibia. We sutured the patellar allograft tendon to the patella using two No. 2-0 FiberWire sutures in Krackow suture technique⁸ (Figures 1B, 1C). We obtained good fixation of the patellar tendon, and the distance between the patellar insertion and the inferior patellar pole was the same as before surgery: 5.57 cm and comparable to the contralateral side (Figures 2A-2C). The patellar allograft and autograft sandwich were secured with additional No. 2-0 FiberWire sutures, and the quadriceps allograft and autograft were secured with the cross-stitch technique with the same material. Fine suturing of the quadriceps tendon was done with No. 0 Vicryl sutures. After the fixation was completed, we tested the stability of the reconstruction and found good flexion up to 120°.

The postoperative protocol consisted of weight-bearing as tolerated in full extension and passive knee ROM, using a continuous passive ROM machine from 0° to 45° for the first 4 weeks, followed by active ROM, increased as tolerated, during the next 8 weeks.

The patient was seen in clinic 3 and 9 months after surgery. At the 3-month follow-up appointment, the patient’s examination showed knee ROM from 0° extension to 130° of flexion, no secondary infection signs, and radiographic evidence of a well-healing patellar allograft with symmetric patellar tendon length to the contralateral side. At 9-month follow-up, the patient’s active ROM was from 0° extension to 140° flexion (Figures 3A, 3B), and he had returned to his preinjury level of functioning.

Discussion

This case report describes the successful reconstruction of a patellar tendon defect with cadaveric tendon–patellar tendon–bone allograft. Extensor mechanism injuries are uncommon in general, and the incidence of patellar tendon injury is higher in men than in women.² Patellar tendon tears occur frequently in active patients younger than 40 years, usually as a result of sudden quadriceps contraction with the knee slightly flexed.¹ Treatment of patellar tendon injury is surgical, and functional outcomes for patients with this injury are equivalent to those of patients with quadriceps tendon injuries or patellar fractures.² Acute patellar tendon tears can be repaired by end-to-end suturing or transosseous tunnel insertion in the tibia or patella.¹ Reinforcement is often added between the patella and tibial tuberosity, using a semitendinosus band or wire.¹ End-to-end suture is performed using a thick resorbable suture. It is important to avoid patella alta during suturing, comparing the position of the patella with the contralateral patella with the knee in 45° of flexion. In proximal avulsion, the tendon is anchored to the bone by 2 thick nonresorbable sutures through 2 parallel bone tunnels to the proximal pole of the patella. Distal avulsion is rare in adults, but it can be managed by using staples or suture anchors.¹

 

End-to-end suturing of chronic patellar tendon defects is difficult more than 45 days after injury primarily because of difficulties in correcting patella alta secondary to the upward force exerted by the quadriceps tendon.^1,3 Extreme situations similar to the case we present warrant Achilles or patellar tendon allograft for reconstruction of the extensor mechanism.^1,3,6,9

Extensor mechanism allograft also provides an effective remedy for severe quadriceps deficiency caused by loss of the patella, patellar tendon, and quadriceps tendon in total knee arthroplasty.¹⁰ However, in such cases, late failure is common, and major quadriceps deficiency occurs after removal of the allograft material.¹⁰ To improve outcome, a novel technique using the medial gastrocnemius muscle transferred to the muscular portion of the vastus medialis and lateralis flaps provides a secure and strong closure of the anterior knee, thereby restoring the extensor mechanism of the knee.¹⁰

Patellar tendon reconstruction with allograft tissue has been successfully used, especially in cases related to chronic patellar tendon ruptures¹¹ and total knee arthroplasty.^6,12-14 Crossett and colleagues¹² showed that, at 2-year follow-up, the average knee score for pain, ROM, and stability had improved from 26 points (range, 6-39 points) before surgery to 81 points (range, 40-92 points). The average knee score for function had also improved: 14 points (range, 0-35 points) before surgery to 53 points (range, 30-90 points).¹² Primary repair may succeed in early intervention, but in an established rupture, allograft reconstruction is often necessary. Achilles tendon is the preferred allograft, with the calcaneus fragment embedded into the proximal tibia as a new tubercle and the tendon sutured into the remaining extensor mechanism.^1,11 The repair is further protected using a cable loop from the superior pole of the patella to a drill hole in the upper tibia.⁹ Techniques have also been described involving passage of the proximal aspect of the allograft tendon through patellar bone tunnels and suture fixation to the native quadriceps tendon.^11,15 However, in our technique, we shaved off the anterior cortex of the patient’s patella to allow a sandwich-type over-position of the allograft to secure fixation to the patella.

Another alternative to allograft reconstruction involves biocompatible scaffolds. Such scaffolds incorporate the use of platelets in a fibrin framework. A CPFS, produced from blood and calcium gluconate to improve healing of patellar tendon defects, has been described in animal studies.⁷ In the rabbit model, CPFS acts as a provisional bioscaffold that can accelerate healing of an injured patellar tendon repair, potentially secondary to several growth factors derived from platelets.⁷ Platelets are biocompatible sources of growth factors, and CPFS can act as a scaffold to restore the mechanical integrity of injured soft tissue.^7,16 In addition, CPFS can act to lower donor-site morbidity associated with harvesting tissue autograft.⁷ However, to our knowledge, such scaffolds have not been used in human trials. The LARS biocompatible ligament (Corin Group PLC, Cirencester, United Kingdom), currently not approved by the US Food and Drug Administration, is used for reconstructions of isolated or multiple knee ligament injuries.¹⁷ This graft requires the presence of healthy tissue with good blood supply from which new tendon or ligament can grow in. Sometimes it is also used for extensor mechanism reconstruction after radical tumor resection around the knee; however, good results are achieved in only 59% of cases,¹⁸ and to our knowledge, only 1 case of primary repair of a patellar tendon rupture has been published.¹⁹

Techniques involving the use of tendon–patellar tendon–bone graft with fixation via the sandwich-type over-position of the allograft for chronic patellar tendon rupture have not been described in the literature. In our patient, given the extensive patellar tendon lesion and inflammation with chronic tissue degeneration, there was no option but to use allograft. To improve the patient’s outcome, we chose the strongest possible allograft, tendon–patellar tendon–bone graft.

Conclusion

Revision patellar tendon reconstruction is a challenging, but necessary, procedure to restore the extensor mechanism of the knee, especially in young, active individuals. Various options to reconstruct the tissue defects are available. Our patient was successfully treated with a tendon–patellar tendon–bone allograft reconstruction.

In 1887, Midelfart¹ first reported on an intra-articular dislocation of the patella, and since then approximately 50 cases have been reported in the worldwide literature.² Also known as an inferior patellar dislocation, these rare traumatic events occur when the patella dislocates intra-articularly. Because the patella commonly rotates about its horizontal axis, the articular surface is facing proximally or distally. The patella becomes lodged within the trochlea and locks the knee joint. Most cases described in the literature involved adolescent boys, with the patella difficult to reduce. Most patients required open reduction, while those who underwent successful closed reduction often needed general anesthesia.³

Similarly, coronal shear fractures of the femoral condyle (ie, Hoffa fractures) are an uncommon fracture pattern typically seen in adults. These fractures are even more infrequent in skeletally immature patients, with fewer than 5 cases documented in the literature.^4-7 In our case report, we present a 14-year-old boy with a coronal shear fracture of the femoral condyle associated with an intra-articular patellar dislocation. To our knowledge, this constellation of injuries has not been reported. Additionally, closed reduction of the patella was successful after intra-articular lidocaine injection, without the need for sedation or general anesthesia. The patient’s guardian provided written informed consent for print and electronic publication of this case report.

Case Report

A 14-year-old boy presented to our institution after sustaining a direct blow to his left knee. The injury occurred as he jumped and landed on a flexed knee while playing with friends. The patient was unable to ambulate after the injury, and his left knee was locked in a slightly flexed position. Examination in the emergency department showed the knee to be held in approximately 60º of flexion, with an obvious bony prominence noted anteriorly over the femoral condyles. The patient was unable to perform a straight leg raise or any active range of motion (ROM) at the knee. Radiographs performed with the knee maintained in flexion confirmed that the patella was displaced into the knee joint and was rotated with the articular surface facing distally. Also noted was a coronal shear fracture of the lateral femoral condyle (Figures 1A, 1B).

The patient received pain medication and an intra-articular lidocaine injection prior to a reduction attempt by the orthopedic resident. With the patient supine, the hip was gently flexed to relax the quadriceps muscle. As the knee was flexed up to 110º, the prominent patella was gripped between the thumb and fingers to gently free and elevate the patella out of the intercondylar notch.

After reduction, an immediate return of normal patellar contour and patellofemoral tracking was observed as the knee was gently extended. There was no obvious defect to the patellar or quadriceps tendons, and the patient was able to perform a straight-leg raise, confirming the integrity of the extensor mechanism. Radiographs performed after the reduction confirmed relocation of the patella in correct anatomic position, as well as a lateral femoral condyle fracture (Figures 2A, 2B). Magnetic resonance imaging (MRI) of the knee confirmed no full-thickness quadriceps or patellar tendon tear. A computed tomography (CT) scan of the knee showed a comminuted fracture of the lateral femoral condyle in the coronal plane, as well as multiple bone fragments within the joint (Figures 3A, 3B). The patient was placed in a bulky soft dressing and underwent open reduction and internal fixation of the fracture.

 

A 10-cm incision was made over the anterior aspect of the knee, and after dissection to the level of the retinaculum, a lateral parapatellar arthrotomy was performed. The patella was retracted medially to identify and free the fracture fragments. The fracture fragments were provisionally reduced and stabilized with three 0.065-in Kirschner wires. An area of osteochondral impaction proximal to the fracture was elevated and allograft bone was incorporated below the articular surface (Figures 4A, 4B). Rigid fixation of the fracture was achieved using 3 screws (2 Bio-Compression Screws [Arthrex Inc., Naples, Florida] and 1 Synthes cannulated screw [Synthes, West Chester, Pennsylvania]). The screws were placed in posteroanterior (PA) direction and inserted into the weight-bearing articular surface of the femoral condyle (Figures 4C, 4D). The screws were countersunk, and stable fixation with compression of the fracture was achieved. Reduction and screw position were verified with fluoroscopic views. The wound was closed in layers, and the patient was discharged home the next day.

Postoperatively, the patient was non-weight-bearing on the affected limb with a hinged-knee brace to allow for knee ROM exercises immediately. He was also given a continuous passive motion device to maintain knee motion. At the 6-week mark, the patient’s fracture alignment appeared to be well-maintained and showed interval healing. Clinically, the patient was noted to have limited knee ROM. The decision was made to take the patient to the operating room primarily for a manipulation under anesthesia and resection of scar tissue from postoperative arthrofibrosis. Arthroscopic screw removal was also planned as a secondary procedure at the same time in order to prevent the possibility of chondral injury from screw migration. During the procedure, the patient was noted to have improved ROM from 5º to 85º premanipulation to 5º to 110º postoperatively. At 3 months after the initial injury, the patient was allowed to begin progressive weight-bearing on the left knee. At most recent follow-up, after 12 months, the patient was able to ambulate and bear weight on the left leg without pain. Plain radiographs show a well-healed fracture with no evidence of collapse of the femoral condyle (Figures 5A, 5B). His active ROM of the left knee was 5º to 110º without pain (Figures 5C, 5D).

 

Discussion

In the vast majority of patellar dislocations, the patella dislocates laterally over the trochlear groove. Inferior, or intra-articular, dislocations of the patella are rare. The mechanism of injury is usually a blow onto the patella with a flexed knee. The 2 groups commonly involved are adolescent boys and the elderly.^8,9 In young men, it is thought that lax patellar attachments place adolescents at higher risk for this type of injury.^10-12 While patella fractures and frank extensor mechanism ruptures are uncommon in this age group, the same mechanism of injury can lead to stripping of the deep fibers of the patellar tendon from the superior pole of the patella.^3,13 The intact superficial fibers of the tendon allow the patella to hinge and displace into the joint.¹⁴

Inferior dislocations of the patella are classified into 2 types based on the orientation of the articular surface and the presence of osteophytes.¹⁵ Type I inferior dislocations occur after a direct blow to a flexed knee forces the superior pole of the patella into the intercondylar notch. Type II dislocations are caused by osteophytes on the superior pole of the patella that become wedged in the intercondylar notch and dislocate the patella inferiorly. In type I dislocations, the patella is rotated in the horizontal plane and the articular surface often faces inferiorly, but type II dislocations do not involve rotation of the articular surface. Type II injuries are seen more commonly in the elderly.

Our patient was able to tolerate a closed reduction of the patella after an intra-articular lidocaine injection, and a successful reduction was achieved without great difficulty. However, the majority of reports describe the need for an open reduction of inferior patellar dislocations.^3,8 When closed reductions were a success, they were performed under general anesthesia or conscious sedation.³ It is thought that the difficulty of reduction results from the tension of the quadriceps muscle pulling the patella superiorly into intercondylar notch.^11,16 However, successful closed reduction may be more likely in patients with less patellar rotation and entrapment within the intercondylar notch, as well as in patients whose knee is near full extension at presentation.^17-19 Successful closed reduction is also seen in elderly patients, where dislocation is generally caused by less forceful impact and held by osteophytes. In these patients, the knee is commonly held in extension.^12,15,20-22

The fracture pattern seen in this case also shows a rare fracture in skeletally immature patients, with only a few case reports in the literature. Isolated coronal plane femur fractures account for 0.65% of all femur fractures and are usually seen in adults after high-energy trauma.²³ In the skeletally immature, the fracture can occur with lower-energy mechanisms. The typical mechanism is thought to be a shearing force to the femur caused by an axial load to the knee in 90° or more of flexion.^4,24 A CT scan is recommended for better identification of the fracture and to plan treatment.^25,26 Because of their intra-articular nature and tenuous blood supply, Hoffa fractures tend to do poorly with nonoperative treatment and are prone to displacement and nonunion.^27,28 The goal of operative treatment is to obtain anatomic reduction and rigid fixation. While operative fixation techniques are varied, screw fixation with multiple smaller diameter screws has equal pullout strength compared to larger screws and may minimize damage to the articular cartilage.^29-31 By preserving blood supply to the fracture, and allowing for early active mobilization, operative treatment generally provides good long-term functional outcomes in these fracture patterns.²⁴

Conclusion

We describe a case in which the patella of an adolescent boy dislocated inferiorly into the knee joint, with an associated coronal shear fracture of the lateral femoral condyle. To our knowledge, this constellation of injuries has not been reported. For this uncommon injury pattern, we recommend a sequential treatment algorithm to minimize morbidity. We recommend first attempting a closed reduction of the patella with adequate pain control to avoid the morbidity associated with general anesthesia. After a successful reduction, an advanced imaging study (eg, MRI) is advisable to assess for concomitant soft-tissue injuries and preoperative planning, if necessary. The mechanism of injury and force required to cause a patellar dislocation of this nature leaves a high likelihood of other injuries. When a fracture is noted on plain radiographs after reduction, a CT scan can provide important information for planning surgical fixation of the fracture. Even in a skeletally immature patient, the principle of direct reduction and stable interfragmentary fixation of an articular fracture is critical for long-term function, even after a significant trauma to the knee.

In 1887, Midelfart¹ first reported on an intra-articular dislocation of the patella, and since then approximately 50 cases have been reported in the worldwide literature.² Also known as an inferior patellar dislocation, these rare traumatic events occur when the patella dislocates intra-articularly. Because the patella commonly rotates about its horizontal axis, the articular surface is facing proximally or distally. The patella becomes lodged within the trochlea and locks the knee joint. Most cases described in the literature involved adolescent boys, with the patella difficult to reduce. Most patients required open reduction, while those who underwent successful closed reduction often needed general anesthesia.³

Similarly, coronal shear fractures of the femoral condyle (ie, Hoffa fractures) are an uncommon fracture pattern typically seen in adults. These fractures are even more infrequent in skeletally immature patients, with fewer than 5 cases documented in the literature.^4-7 In our case report, we present a 14-year-old boy with a coronal shear fracture of the femoral condyle associated with an intra-articular patellar dislocation. To our knowledge, this constellation of injuries has not been reported. Additionally, closed reduction of the patella was successful after intra-articular lidocaine injection, without the need for sedation or general anesthesia. The patient’s guardian provided written informed consent for print and electronic publication of this case report.

Case Report

A 14-year-old boy presented to our institution after sustaining a direct blow to his left knee. The injury occurred as he jumped and landed on a flexed knee while playing with friends. The patient was unable to ambulate after the injury, and his left knee was locked in a slightly flexed position. Examination in the emergency department showed the knee to be held in approximately 60º of flexion, with an obvious bony prominence noted anteriorly over the femoral condyles. The patient was unable to perform a straight leg raise or any active range of motion (ROM) at the knee. Radiographs performed with the knee maintained in flexion confirmed that the patella was displaced into the knee joint and was rotated with the articular surface facing distally. Also noted was a coronal shear fracture of the lateral femoral condyle (Figures 1A, 1B).

The patient received pain medication and an intra-articular lidocaine injection prior to a reduction attempt by the orthopedic resident. With the patient supine, the hip was gently flexed to relax the quadriceps muscle. As the knee was flexed up to 110º, the prominent patella was gripped between the thumb and fingers to gently free and elevate the patella out of the intercondylar notch.

After reduction, an immediate return of normal patellar contour and patellofemoral tracking was observed as the knee was gently extended. There was no obvious defect to the patellar or quadriceps tendons, and the patient was able to perform a straight-leg raise, confirming the integrity of the extensor mechanism. Radiographs performed after the reduction confirmed relocation of the patella in correct anatomic position, as well as a lateral femoral condyle fracture (Figures 2A, 2B). Magnetic resonance imaging (MRI) of the knee confirmed no full-thickness quadriceps or patellar tendon tear. A computed tomography (CT) scan of the knee showed a comminuted fracture of the lateral femoral condyle in the coronal plane, as well as multiple bone fragments within the joint (Figures 3A, 3B). The patient was placed in a bulky soft dressing and underwent open reduction and internal fixation of the fracture.

 

A 10-cm incision was made over the anterior aspect of the knee, and after dissection to the level of the retinaculum, a lateral parapatellar arthrotomy was performed. The patella was retracted medially to identify and free the fracture fragments. The fracture fragments were provisionally reduced and stabilized with three 0.065-in Kirschner wires. An area of osteochondral impaction proximal to the fracture was elevated and allograft bone was incorporated below the articular surface (Figures 4A, 4B). Rigid fixation of the fracture was achieved using 3 screws (2 Bio-Compression Screws [Arthrex Inc., Naples, Florida] and 1 Synthes cannulated screw [Synthes, West Chester, Pennsylvania]). The screws were placed in posteroanterior (PA) direction and inserted into the weight-bearing articular surface of the femoral condyle (Figures 4C, 4D). The screws were countersunk, and stable fixation with compression of the fracture was achieved. Reduction and screw position were verified with fluoroscopic views. The wound was closed in layers, and the patient was discharged home the next day.

Postoperatively, the patient was non-weight-bearing on the affected limb with a hinged-knee brace to allow for knee ROM exercises immediately. He was also given a continuous passive motion device to maintain knee motion. At the 6-week mark, the patient’s fracture alignment appeared to be well-maintained and showed interval healing. Clinically, the patient was noted to have limited knee ROM. The decision was made to take the patient to the operating room primarily for a manipulation under anesthesia and resection of scar tissue from postoperative arthrofibrosis. Arthroscopic screw removal was also planned as a secondary procedure at the same time in order to prevent the possibility of chondral injury from screw migration. During the procedure, the patient was noted to have improved ROM from 5º to 85º premanipulation to 5º to 110º postoperatively. At 3 months after the initial injury, the patient was allowed to begin progressive weight-bearing on the left knee. At most recent follow-up, after 12 months, the patient was able to ambulate and bear weight on the left leg without pain. Plain radiographs show a well-healed fracture with no evidence of collapse of the femoral condyle (Figures 5A, 5B). His active ROM of the left knee was 5º to 110º without pain (Figures 5C, 5D).

 

Discussion

In the vast majority of patellar dislocations, the patella dislocates laterally over the trochlear groove. Inferior, or intra-articular, dislocations of the patella are rare. The mechanism of injury is usually a blow onto the patella with a flexed knee. The 2 groups commonly involved are adolescent boys and the elderly.^8,9 In young men, it is thought that lax patellar attachments place adolescents at higher risk for this type of injury.^10-12 While patella fractures and frank extensor mechanism ruptures are uncommon in this age group, the same mechanism of injury can lead to stripping of the deep fibers of the patellar tendon from the superior pole of the patella.^3,13 The intact superficial fibers of the tendon allow the patella to hinge and displace into the joint.¹⁴

Inferior dislocations of the patella are classified into 2 types based on the orientation of the articular surface and the presence of osteophytes.¹⁵ Type I inferior dislocations occur after a direct blow to a flexed knee forces the superior pole of the patella into the intercondylar notch. Type II dislocations are caused by osteophytes on the superior pole of the patella that become wedged in the intercondylar notch and dislocate the patella inferiorly. In type I dislocations, the patella is rotated in the horizontal plane and the articular surface often faces inferiorly, but type II dislocations do not involve rotation of the articular surface. Type II injuries are seen more commonly in the elderly.

Our patient was able to tolerate a closed reduction of the patella after an intra-articular lidocaine injection, and a successful reduction was achieved without great difficulty. However, the majority of reports describe the need for an open reduction of inferior patellar dislocations.^3,8 When closed reductions were a success, they were performed under general anesthesia or conscious sedation.³ It is thought that the difficulty of reduction results from the tension of the quadriceps muscle pulling the patella superiorly into intercondylar notch.^11,16 However, successful closed reduction may be more likely in patients with less patellar rotation and entrapment within the intercondylar notch, as well as in patients whose knee is near full extension at presentation.^17-19 Successful closed reduction is also seen in elderly patients, where dislocation is generally caused by less forceful impact and held by osteophytes. In these patients, the knee is commonly held in extension.^12,15,20-22

The fracture pattern seen in this case also shows a rare fracture in skeletally immature patients, with only a few case reports in the literature. Isolated coronal plane femur fractures account for 0.65% of all femur fractures and are usually seen in adults after high-energy trauma.²³ In the skeletally immature, the fracture can occur with lower-energy mechanisms. The typical mechanism is thought to be a shearing force to the femur caused by an axial load to the knee in 90° or more of flexion.^4,24 A CT scan is recommended for better identification of the fracture and to plan treatment.^25,26 Because of their intra-articular nature and tenuous blood supply, Hoffa fractures tend to do poorly with nonoperative treatment and are prone to displacement and nonunion.^27,28 The goal of operative treatment is to obtain anatomic reduction and rigid fixation. While operative fixation techniques are varied, screw fixation with multiple smaller diameter screws has equal pullout strength compared to larger screws and may minimize damage to the articular cartilage.^29-31 By preserving blood supply to the fracture, and allowing for early active mobilization, operative treatment generally provides good long-term functional outcomes in these fracture patterns.²⁴

Conclusion

We describe a case in which the patella of an adolescent boy dislocated inferiorly into the knee joint, with an associated coronal shear fracture of the lateral femoral condyle. To our knowledge, this constellation of injuries has not been reported. For this uncommon injury pattern, we recommend a sequential treatment algorithm to minimize morbidity. We recommend first attempting a closed reduction of the patella with adequate pain control to avoid the morbidity associated with general anesthesia. After a successful reduction, an advanced imaging study (eg, MRI) is advisable to assess for concomitant soft-tissue injuries and preoperative planning, if necessary. The mechanism of injury and force required to cause a patellar dislocation of this nature leaves a high likelihood of other injuries. When a fracture is noted on plain radiographs after reduction, a CT scan can provide important information for planning surgical fixation of the fracture. Even in a skeletally immature patient, the principle of direct reduction and stable interfragmentary fixation of an articular fracture is critical for long-term function, even after a significant trauma to the knee.

In 1887, Midelfart¹ first reported on an intra-articular dislocation of the patella, and since then approximately 50 cases have been reported in the worldwide literature.² Also known as an inferior patellar dislocation, these rare traumatic events occur when the patella dislocates intra-articularly. Because the patella commonly rotates about its horizontal axis, the articular surface is facing proximally or distally. The patella becomes lodged within the trochlea and locks the knee joint. Most cases described in the literature involved adolescent boys, with the patella difficult to reduce. Most patients required open reduction, while those who underwent successful closed reduction often needed general anesthesia.³

Similarly, coronal shear fractures of the femoral condyle (ie, Hoffa fractures) are an uncommon fracture pattern typically seen in adults. These fractures are even more infrequent in skeletally immature patients, with fewer than 5 cases documented in the literature.^4-7 In our case report, we present a 14-year-old boy with a coronal shear fracture of the femoral condyle associated with an intra-articular patellar dislocation. To our knowledge, this constellation of injuries has not been reported. Additionally, closed reduction of the patella was successful after intra-articular lidocaine injection, without the need for sedation or general anesthesia. The patient’s guardian provided written informed consent for print and electronic publication of this case report.

Case Report

A 14-year-old boy presented to our institution after sustaining a direct blow to his left knee. The injury occurred as he jumped and landed on a flexed knee while playing with friends. The patient was unable to ambulate after the injury, and his left knee was locked in a slightly flexed position. Examination in the emergency department showed the knee to be held in approximately 60º of flexion, with an obvious bony prominence noted anteriorly over the femoral condyles. The patient was unable to perform a straight leg raise or any active range of motion (ROM) at the knee. Radiographs performed with the knee maintained in flexion confirmed that the patella was displaced into the knee joint and was rotated with the articular surface facing distally. Also noted was a coronal shear fracture of the lateral femoral condyle (Figures 1A, 1B).

The patient received pain medication and an intra-articular lidocaine injection prior to a reduction attempt by the orthopedic resident. With the patient supine, the hip was gently flexed to relax the quadriceps muscle. As the knee was flexed up to 110º, the prominent patella was gripped between the thumb and fingers to gently free and elevate the patella out of the intercondylar notch.

After reduction, an immediate return of normal patellar contour and patellofemoral tracking was observed as the knee was gently extended. There was no obvious defect to the patellar or quadriceps tendons, and the patient was able to perform a straight-leg raise, confirming the integrity of the extensor mechanism. Radiographs performed after the reduction confirmed relocation of the patella in correct anatomic position, as well as a lateral femoral condyle fracture (Figures 2A, 2B). Magnetic resonance imaging (MRI) of the knee confirmed no full-thickness quadriceps or patellar tendon tear. A computed tomography (CT) scan of the knee showed a comminuted fracture of the lateral femoral condyle in the coronal plane, as well as multiple bone fragments within the joint (Figures 3A, 3B). The patient was placed in a bulky soft dressing and underwent open reduction and internal fixation of the fracture.

 

A 10-cm incision was made over the anterior aspect of the knee, and after dissection to the level of the retinaculum, a lateral parapatellar arthrotomy was performed. The patella was retracted medially to identify and free the fracture fragments. The fracture fragments were provisionally reduced and stabilized with three 0.065-in Kirschner wires. An area of osteochondral impaction proximal to the fracture was elevated and allograft bone was incorporated below the articular surface (Figures 4A, 4B). Rigid fixation of the fracture was achieved using 3 screws (2 Bio-Compression Screws [Arthrex Inc., Naples, Florida] and 1 Synthes cannulated screw [Synthes, West Chester, Pennsylvania]). The screws were placed in posteroanterior (PA) direction and inserted into the weight-bearing articular surface of the femoral condyle (Figures 4C, 4D). The screws were countersunk, and stable fixation with compression of the fracture was achieved. Reduction and screw position were verified with fluoroscopic views. The wound was closed in layers, and the patient was discharged home the next day.

Postoperatively, the patient was non-weight-bearing on the affected limb with a hinged-knee brace to allow for knee ROM exercises immediately. He was also given a continuous passive motion device to maintain knee motion. At the 6-week mark, the patient’s fracture alignment appeared to be well-maintained and showed interval healing. Clinically, the patient was noted to have limited knee ROM. The decision was made to take the patient to the operating room primarily for a manipulation under anesthesia and resection of scar tissue from postoperative arthrofibrosis. Arthroscopic screw removal was also planned as a secondary procedure at the same time in order to prevent the possibility of chondral injury from screw migration. During the procedure, the patient was noted to have improved ROM from 5º to 85º premanipulation to 5º to 110º postoperatively. At 3 months after the initial injury, the patient was allowed to begin progressive weight-bearing on the left knee. At most recent follow-up, after 12 months, the patient was able to ambulate and bear weight on the left leg without pain. Plain radiographs show a well-healed fracture with no evidence of collapse of the femoral condyle (Figures 5A, 5B). His active ROM of the left knee was 5º to 110º without pain (Figures 5C, 5D).

 

Discussion

In the vast majority of patellar dislocations, the patella dislocates laterally over the trochlear groove. Inferior, or intra-articular, dislocations of the patella are rare. The mechanism of injury is usually a blow onto the patella with a flexed knee. The 2 groups commonly involved are adolescent boys and the elderly.^8,9 In young men, it is thought that lax patellar attachments place adolescents at higher risk for this type of injury.^10-12 While patella fractures and frank extensor mechanism ruptures are uncommon in this age group, the same mechanism of injury can lead to stripping of the deep fibers of the patellar tendon from the superior pole of the patella.^3,13 The intact superficial fibers of the tendon allow the patella to hinge and displace into the joint.¹⁴

Inferior dislocations of the patella are classified into 2 types based on the orientation of the articular surface and the presence of osteophytes.¹⁵ Type I inferior dislocations occur after a direct blow to a flexed knee forces the superior pole of the patella into the intercondylar notch. Type II dislocations are caused by osteophytes on the superior pole of the patella that become wedged in the intercondylar notch and dislocate the patella inferiorly. In type I dislocations, the patella is rotated in the horizontal plane and the articular surface often faces inferiorly, but type II dislocations do not involve rotation of the articular surface. Type II injuries are seen more commonly in the elderly.

Our patient was able to tolerate a closed reduction of the patella after an intra-articular lidocaine injection, and a successful reduction was achieved without great difficulty. However, the majority of reports describe the need for an open reduction of inferior patellar dislocations.^3,8 When closed reductions were a success, they were performed under general anesthesia or conscious sedation.³ It is thought that the difficulty of reduction results from the tension of the quadriceps muscle pulling the patella superiorly into intercondylar notch.^11,16 However, successful closed reduction may be more likely in patients with less patellar rotation and entrapment within the intercondylar notch, as well as in patients whose knee is near full extension at presentation.^17-19 Successful closed reduction is also seen in elderly patients, where dislocation is generally caused by less forceful impact and held by osteophytes. In these patients, the knee is commonly held in extension.^12,15,20-22

The fracture pattern seen in this case also shows a rare fracture in skeletally immature patients, with only a few case reports in the literature. Isolated coronal plane femur fractures account for 0.65% of all femur fractures and are usually seen in adults after high-energy trauma.²³ In the skeletally immature, the fracture can occur with lower-energy mechanisms. The typical mechanism is thought to be a shearing force to the femur caused by an axial load to the knee in 90° or more of flexion.^4,24 A CT scan is recommended for better identification of the fracture and to plan treatment.^25,26 Because of their intra-articular nature and tenuous blood supply, Hoffa fractures tend to do poorly with nonoperative treatment and are prone to displacement and nonunion.^27,28 The goal of operative treatment is to obtain anatomic reduction and rigid fixation. While operative fixation techniques are varied, screw fixation with multiple smaller diameter screws has equal pullout strength compared to larger screws and may minimize damage to the articular cartilage.^29-31 By preserving blood supply to the fracture, and allowing for early active mobilization, operative treatment generally provides good long-term functional outcomes in these fracture patterns.²⁴

Conclusion

We describe a case in which the patella of an adolescent boy dislocated inferiorly into the knee joint, with an associated coronal shear fracture of the lateral femoral condyle. To our knowledge, this constellation of injuries has not been reported. For this uncommon injury pattern, we recommend a sequential treatment algorithm to minimize morbidity. We recommend first attempting a closed reduction of the patella with adequate pain control to avoid the morbidity associated with general anesthesia. After a successful reduction, an advanced imaging study (eg, MRI) is advisable to assess for concomitant soft-tissue injuries and preoperative planning, if necessary. The mechanism of injury and force required to cause a patellar dislocation of this nature leaves a high likelihood of other injuries. When a fracture is noted on plain radiographs after reduction, a CT scan can provide important information for planning surgical fixation of the fracture. Even in a skeletally immature patient, the principle of direct reduction and stable interfragmentary fixation of an articular fracture is critical for long-term function, even after a significant trauma to the knee.