Peter Curtis, MD

Alternative or complementary approaches to medical care are gaining loyalty from patients and increasing interest from the allopathic health care community.^1-4 In particular, professional organizations in the areas of acupuncture and manual therapy are offering and expanding continuing medical education (CME) programs in these fields for allopathic physicians, though there are few published data on their effectiveness.^5,6

The direct impact of CME on patients and clinical practice has been little studied, particularly in relation to the treatment of low back pain.⁷ Cherkin and colleagues^8,9 undertook an evaluation of a didactic CME program on low back pain in 1991 by studying patient satisfaction and provider attitudes. It appeared that the patients of providers who professed greater confidence in managing low back pain were more satisfied with their care, though negative attitudes previously expressed by clinicians toward low back pain did not change significantly after CME. In a discussion of this study it was suggested that patients might be seeking information and practical guidance rather than a cure or empathy.¹⁰ However, the investigators did not study the effects of modifying physical examination and manual skills in the care of these patients, factors that might play an important role in outcomes.

Although greater patient satisfaction has been associated with chiropractic care (which emphasizes manual skills) than that given by primary care physicians, there appears to be no association of satisfaction with practitioner self-confidence or days to functional recovery of the patient.^11,12

We developed a workshop for generalist clinicians in the skills of assessment, limited manual therapy, and a graded exercise program, and in a randomized controlled trial evaluated clinician self-efficacy and patient outcomes for acute low back pain.^13,14 We demonstrated that allopathic generalist physicians could be effectively trained in limited manual therapy with self-reported increased competence in managing low back pain. The patients receiving therapy showed a trend toward feeling completely better more quickly but reported no greater satisfaction or objective functional improvement in terms of activities than patients in the control group who were receiving only high-quality conventional care through workshop training.¹⁴

Of 31 physicians recruited into the manual therapy trial, 13 had previously been involved in a cohort study of utilization and back care therapy given by 208 practitioners (115 primary care generalists) to 1633 patients (644 patients of primary care generalists).¹¹ We examined the outcomes of patients with low back pain from the practices of these 13 physicians before (data from the cohort study) and after an intensive hands-on training workshop (data from the manual therapy trial), using similar patient recruitment methods and evaluation instruments ([Figure 1]. Our hypothesis was that this training in manual and assessment skills would improve patient outcomes and satisfaction.

Methods

The initial cohort study was undertaken to examine the prevalence, care seeking, and outcomes of acute low back pain in the state of North Carolina. No interventions were undertaken in this study. Methods and measures used in its implementation have been described previously by Carey and coworkers.¹¹ Clinicians were randomly selected from medical and chiropractic licensure files (primary care generalists, chiropractic physicians, and orthopedic surgeons). To be included in the cohort study clinicians had to see ambulatory patients at least 50% of the time and provide first contact care for acute low back pain. Of the 208 clinicians from different disciplines recruited into the study, 115 were primary care physicians. During a 10-month period consecutive patients with acute or subacute low back pain (<10 weeks) were enrolled unless they had received previous care for the episode, had received previous back surgery, had a history of cancer, were pregnant, had no telephone, or were unable to speak English. Patients were contacted by telephone after the visit by staff members of the University of North Carolina Survey Research Unit, and interviews were undertaken at baseline, 2, 4, 8, 12, and 24 weeks.

These interviews included questions about details of the back pain episode, medications and other therapies used, tests performed, work and compensation status, demographic data, and income level. Outcome data included responses to the 23-item Roland-Morris Back Disability Questionnaire.¹⁵ We also asked when the patients considered they were able to perform their usual daily activities after the back pain. Patient satisfaction was assessed on how well the physician communicated, listened, gave information and explained the cause of back pain, whether a detailed history was taken and the back examined carefully, and if advice was given on pain management, prevention, and activities of sleeping and sitting (yes/no responses). Other satisfaction items (overall treatment, pain relief provided, and patient abilities to walk, socialize, and work) were rated on a 5-point Likert scale (poor, fair, good, very good, or excellent). This was subsequently adapted to a dichotomous response. Clinical and utilization data were obtained from charts in the physicians’ offices to allow validation of survey variables.

The randomized trial of the effectiveness of limited manual therapy was started in 1995, 12 months after the closure of the cohort study. Patients were recruited by 31 generalist physicians (13 from the earlier cohort study and 18 volunteers from the 630 physicians on the North Carolina physician master file). The same inclusion and exclusion criteria from the cohort study were used except that the acceptable age range was 21 to 65 (compared with 75 years) and patients had no osteopenia, severe arthritis, morbid obesity, or neurological deficits and had not received previous manual therapy by the physician. These additional exclusion criteria were necessary to avoid possible adverse effects of manual therapy in the presence of disease and to eliminate patient bias of a preference for manual therapy based on previous experience.

For each arm of the study, after the first office visit the identical telephone interview questions and schedule used in the cohort study were implemented for up to 8 weeks. Chart abstraction methods and variables were also identical except that additional data were collected on the specifics of manual therapy given at each visit.

Two sequential weekend workshops with a refresher session for each of the 31 physicians (developed and given to 9 physicians per workshop by 3 family physicians skilled in manual therapy) were implemented before the start of the clinical trial. The purpose was to train these physicians in quality care for low back pain (explained to patients as enhanced care—the control arm) and in standardized limited manual therapy (the main component of the intervention arm).¹³ The term “enhanced care” was developed to minimize the impression for patients during randomization that they might either receive something special (manual therapy) or just routine care—both options needed to appear to be special to reduce placebo bias.

Training for the enhanced low back pain care arm included physician education in (1) the directed history and physical examination using Agency for Health Care Policy and Research (AHCPR) guidelines,¹⁶ (2) review of the efficacy of imaging and laboratory testing, (3) review of the efficacy of treatment modalities, and (4) use of specially designed patient handouts emphasizing progressive exercises, daily activities, and early return to function.

Training for the limited manual therapy arm included the enhanced low back pain skills plus:

• manual therapy, consisting of: (1) principles of manual therapy and explanatory models, (2) instruction in motion testing, and (3) instruction in limited manual therapy skills (soft-tissue, muscle energy, and high-velocity low-amplitude techniques involving psoas and piriformis muscles—lumbar spine, lumbosacral junction, and sacroiliac joints)
• workshop training and demonstrated competence in low back care on simulated patients
• guidance and practice in integrating limited manual therapy into the office visit
• education and practice in recruiting patients and in the procedures of random assignment of those patients to the control (enhanced care) arm or the manual therapy arm

After training, the physicians returned to their practices and worked on their newly learned skill for approximately 3 months before enrolling patients. At an agreed time they began to enroll patients and randomized them to enhanced care or enhanced care plus limited manual therapy using a blinded method.

Analysis

Using the patients of the 13 physicians active in both the original cohort study and the subsequent randomized trial of limited manual therapy, we compared outcomes between 3 groups of patients: (1) those whose usual care was only observed in the earlier cohort study, (2) those receiving enhanced care (control arm) in the randomized trial, and (3) those receiving enhanced care plus manual therapy (intervention arm) in the randomized trial. The major variables included in the analyses were age, sex, education, household income, duration of low back pain episode for more than 2 weeks, presence of sciatica, workers’ compensation status, and the Work Adaptation, Partnership, Growth, Affection, and Resolve Survey (a measure of job satisfaction).¹⁶ In each of the studies, outcome measures from repeated interviews included data on functional status over time and pain levels. Data on satisfaction with care, return to work, and time to functional and complete recovery were obtained either at 8 weeks or when the patients were better. The main outcome measures were the Roland-Morris adaptation of the Sickness Impact Profile (a 23-item scale with high scores indicating significant dysfunction), patients’ report of being all better or functionally better, and the date they were able to return to performing their usual daily activities.^10,14 Patient satisfaction measures were based on the scale developed by Cherkin and colleagues.⁸ The patient was the unit of analysis.

Pearson’s chi-square was used when comparing the 3 patient groups by physician performance and patient satisfaction, adjusting for baseline differences. Linear modeling was used to examine the relationship of manual therapy to functional status (Roland-Morris score). Cox proportional hazard modeling was undertaken to identify survival curves of time to functional recovery. In all analyses, standard errors were corrected for any intraclass correlation due to nonindependence of patients seeing the same physician.¹⁷

Results

The 13 physicians cared for 120 patients in the observational study and 191 patients in the randomized trial [Figure 1]. In each of the studies very similar numbers of patients were seen by each physician. Within the 2 arms of the randomized trial of manual therapy, baseline characteristics were essentially the same [Table 1].

There were some differences in baseline characteristics between patients in the cohort study and the randomized trial. More patients in the randomized trial (41.4% vs 25%, P=.01) had significantly higher severe baseline dysfunction (Roland-Morris score=16-23) than in the cohort study. The mean baseline Roland Morris score was 10.0 for the cohort study patients compared with 12.5 for the manual therapy study patients (P=.03). There were more patients on workers’ compensation in the cohort study (35%) than in the manual therapy study (16.3%, P=.002), and fewer had been employed in the previous 3 months (80.8% vs 90.0%, P=.02).

Patients in both arms of the randomized manual therapy trial were significantly more satisfied than their counterparts in the earlier cohort study in terms of how their physician gave care in the clinical encounter and whether they received effective advice [Table 2]. Patients participating in the manual therapy trial were also more satisfied with their pain relief, their physicians’ overall treatment of back pain, and their ability to perform activities of daily living. Specific items of clinical performance where differences were noted included: the physician took a detailed history; gave useful advice on pain, preventive measures, sleeping, and sitting strategies; and provided back exercises. There were no differences in patient ratings of the physician’s ability to listen effectively, perform a careful physical examination, and explain the cause of their back pain. There were no differences in general health status between the cohort and manual therapy study patients.

When adjusted for baseline function, the presence of sciatica, duration of pain, employment status, workers’ compensation, and income of more than $20,000, mean functional outcomes measured by Roland-Morris scores at 2 weeks were 8.2 for the patients in the cohort study and 6.7 in the manual therapy trial (P=.03); at 4 weeks mean scores were 7.2 for the cohort and 5.2 for patients in the manual therapy trial (P=.02), and at 8 weeks scores were 6.7 and 3.6, respectively (P=.002). These were clinically significant differences showing that all patients in the clinical trial had lower functional disability levels during an 8-week period than patients of the same physicians in the cohort study.

After controlling for baseline Roland-Morris score, duration of low back pain, sciatica, employment status, workers’ compensation, and income more than $20,000, time to functional recovery reported by the patient (using Cox proportional hazard modeling) between the 3 groups of patients was as follows: (1) manual therapy + enhanced care versus cohort: hazard ratio (HR)=1.16; 95% confidence interval (CI), 0.85-1.58; (2) enhanced care alone versus cohort: HR=1.13; 95% CI, 0.82-1.54; and (3) manual therapy + enhanced care versus enhanced care alone: HR=1.03; 95% CI, 0.75-1.40. None of these HRs were significant [Figure 2].

Discussion

Data from patients of 13 physicians involved in an observational study of back care, followed by a randomized trial of the effect of additional clinical skills developed by hands-on training, provide an unusual opportunity to study patient outcomes and physician performance over time. Similar eligibility and exclusion criteria, data collection methods, and outcome measures were used in both studies, allowing us to directly compare the variables of interest.

After controlling for confounding factors and physician clustering effect, patients in the clinical trial of manual therapy had significantly more baseline dysfunction at the index visit but still recovered more rapidly by self-report. After workshop training for the physicians, the proportion of patients who reported effective evaluation and management of their back problem increased substantially.

There were no differences in the 2 studies in the proportions of patients reporting on how effectively their physician listened to them, explained causation, and discussed occupational issues. These latter activities were not specifically addressed in the training workshop, which concentrated on clinical evaluation, manual techniques, and issues of physical rehabilitation. One would expect that a general placebo effect on patients of the training would increase all parameters of their perceptions of care, so the workshop may have produced specific learning effects on the clinicians. Despite a trend favoring the group receiving care from the “trained” physicians, there were no significant differences in how patients perceived the quality of the physician’s physical examination of their back—an item that was particularly emphasized in the workshops. This aspect of physician performance was already highly rated in the cohort group and may have been less likely to show improvement, given the need to know what constitutes a superior examination technique.

The improved reported performances of physicians and patient outcomes were noted in both arms of the manual therapy trial, compared with those of patients in the earlier cohort study, though there was no difference in time to full functional recovery between the 2 studies. The inconsistency between outcomes (Roland-Morris scores and time to functional recovery) is probably explainable by the fact that they measure different patient perceptions of back problems—specific versus global recovery. This inconsistency of measures has been noted in other studies of low back pain interventions.¹⁸

The improved outcomes of patients in the randomized trial compared with those in the cohort may be because of specific elements of the study applicable to all patients or may have been due to unmeasured baseline differences. The patients in the randomized trial were more impaired at baseline, which would tend toward worse rather than better outcomes if severity was not completely controlled for. There are several possible explanations for these findings: (1) workshop training did improve physician knowledge and skills; (2) involvement of patients in a clinical trial in which an intervention (enhanced care) was given in both arms of the study (one also receiving manual therapy) could heighten the overall positive effect; (3) the clinical trial involved more visits (average=3.6) than with patients in the first study (1.3)—this could add significantly to patient satisfaction and perceptions of good care; and (4) the recruited physicians were a special group of interested and motivated individuals who by their nature would produce better outcomes in a clinical trial.

Limitations

There are limitations to our findings and conclusions. There were differences in exclusion criteria that might have reduced the number of unhealthy people recruited into the manual therapy trial compared with the cohort study. This could have led to better outcomes, though we doubt that these differences made much impact given the average age of the patients (40 years).

Although we adjusted for baseline differences (income, workers’ compensation, and employment status), we are not sure why these differences occurred. One possibility is that the rapid population and commercial growth and high employment rates that occurred in the state of North Carolina in the time between the 2 studies improved the economic characteristics of patients presenting to the physicians over time. It is also possible that patients with higher incomes and fewer employment difficulties would be more likely to rate physician communication and management more highly and improve more rapidly.

The global effect on clinician knowledge, skills, and performance of a 3-year span of evolving clinical practice and involvement in low back pain studies (other than participating in a training workshop) cannot be quantified. For example, improved performance and outcomes might have been related to the publication of the AHCPR back pain guidelines in 1994, approximately 6 months before the start of the manual therapy study.¹⁶ However, at the low back pain workshop (where only the AHCPR “red flags” were presented) the participants seemed to be only minimally aware of these guidelines.

If the improved outcomes noted in this study were mainly because of the passage of time rather than workshop training, this provides an interesting insight into how practice changes for the better.

Patient satisfaction with care has been shown to correlate with outcomes.^19,20 Deyo and Diehl suggested that dissatisfaction with care for low back pain was related to failure to obtain an adequate explanation from the physician, while Cherkin and colleagues proposed that lack of confidence in management and negative attitudes of clinicians might be key issues to be addressed in achieving better outcomes.^8-10,21,22 However, didactic training to remedy these problems did not appear to be very effective in improving satisfaction. Following up on these suggestions, Smucker and coworkers,¹² using the large North Carolina cohort study, showed that clinician self-confidence (allopathic and chiropractic physicians) did not predict patient outcomes but commented that communication, time spent with the patient, and manual evaluation and treatment skills might be important variables affecting outcome.¹²

The margin of differences in outcomes shown in our preintervention and postintervention analysis leads us to suggest that allopathic physicians using a brief systematic evaluation and hands-on regional physical examination, sound advice on pain management and prevention, and an increasingly active exercise program can modestly improve early patient functioning and satisfaction in acute low back pain. Whether training in limited manual therapy adds to this benefit is unclear and must be taken into account in relation to the current expansion of CME in manipulative skills for allopathic physicians. The costs and benefits of providing this training—with the possibility of needing one extra office visit or more to fully implement enhanced care—would need to be assessed.²³

Alternative or complementary approaches to medical care are gaining loyalty from patients and increasing interest from the allopathic health care community.^1-4 In particular, professional organizations in the areas of acupuncture and manual therapy are offering and expanding continuing medical education (CME) programs in these fields for allopathic physicians, though there are few published data on their effectiveness.^5,6

The direct impact of CME on patients and clinical practice has been little studied, particularly in relation to the treatment of low back pain.⁷ Cherkin and colleagues^8,9 undertook an evaluation of a didactic CME program on low back pain in 1991 by studying patient satisfaction and provider attitudes. It appeared that the patients of providers who professed greater confidence in managing low back pain were more satisfied with their care, though negative attitudes previously expressed by clinicians toward low back pain did not change significantly after CME. In a discussion of this study it was suggested that patients might be seeking information and practical guidance rather than a cure or empathy.¹⁰ However, the investigators did not study the effects of modifying physical examination and manual skills in the care of these patients, factors that might play an important role in outcomes.

Although greater patient satisfaction has been associated with chiropractic care (which emphasizes manual skills) than that given by primary care physicians, there appears to be no association of satisfaction with practitioner self-confidence or days to functional recovery of the patient.^11,12

We developed a workshop for generalist clinicians in the skills of assessment, limited manual therapy, and a graded exercise program, and in a randomized controlled trial evaluated clinician self-efficacy and patient outcomes for acute low back pain.^13,14 We demonstrated that allopathic generalist physicians could be effectively trained in limited manual therapy with self-reported increased competence in managing low back pain. The patients receiving therapy showed a trend toward feeling completely better more quickly but reported no greater satisfaction or objective functional improvement in terms of activities than patients in the control group who were receiving only high-quality conventional care through workshop training.¹⁴

Of 31 physicians recruited into the manual therapy trial, 13 had previously been involved in a cohort study of utilization and back care therapy given by 208 practitioners (115 primary care generalists) to 1633 patients (644 patients of primary care generalists).¹¹ We examined the outcomes of patients with low back pain from the practices of these 13 physicians before (data from the cohort study) and after an intensive hands-on training workshop (data from the manual therapy trial), using similar patient recruitment methods and evaluation instruments ([Figure 1]. Our hypothesis was that this training in manual and assessment skills would improve patient outcomes and satisfaction.

Methods

The initial cohort study was undertaken to examine the prevalence, care seeking, and outcomes of acute low back pain in the state of North Carolina. No interventions were undertaken in this study. Methods and measures used in its implementation have been described previously by Carey and coworkers.¹¹ Clinicians were randomly selected from medical and chiropractic licensure files (primary care generalists, chiropractic physicians, and orthopedic surgeons). To be included in the cohort study clinicians had to see ambulatory patients at least 50% of the time and provide first contact care for acute low back pain. Of the 208 clinicians from different disciplines recruited into the study, 115 were primary care physicians. During a 10-month period consecutive patients with acute or subacute low back pain (<10 weeks) were enrolled unless they had received previous care for the episode, had received previous back surgery, had a history of cancer, were pregnant, had no telephone, or were unable to speak English. Patients were contacted by telephone after the visit by staff members of the University of North Carolina Survey Research Unit, and interviews were undertaken at baseline, 2, 4, 8, 12, and 24 weeks.

These interviews included questions about details of the back pain episode, medications and other therapies used, tests performed, work and compensation status, demographic data, and income level. Outcome data included responses to the 23-item Roland-Morris Back Disability Questionnaire.¹⁵ We also asked when the patients considered they were able to perform their usual daily activities after the back pain. Patient satisfaction was assessed on how well the physician communicated, listened, gave information and explained the cause of back pain, whether a detailed history was taken and the back examined carefully, and if advice was given on pain management, prevention, and activities of sleeping and sitting (yes/no responses). Other satisfaction items (overall treatment, pain relief provided, and patient abilities to walk, socialize, and work) were rated on a 5-point Likert scale (poor, fair, good, very good, or excellent). This was subsequently adapted to a dichotomous response. Clinical and utilization data were obtained from charts in the physicians’ offices to allow validation of survey variables.

The randomized trial of the effectiveness of limited manual therapy was started in 1995, 12 months after the closure of the cohort study. Patients were recruited by 31 generalist physicians (13 from the earlier cohort study and 18 volunteers from the 630 physicians on the North Carolina physician master file). The same inclusion and exclusion criteria from the cohort study were used except that the acceptable age range was 21 to 65 (compared with 75 years) and patients had no osteopenia, severe arthritis, morbid obesity, or neurological deficits and had not received previous manual therapy by the physician. These additional exclusion criteria were necessary to avoid possible adverse effects of manual therapy in the presence of disease and to eliminate patient bias of a preference for manual therapy based on previous experience.

For each arm of the study, after the first office visit the identical telephone interview questions and schedule used in the cohort study were implemented for up to 8 weeks. Chart abstraction methods and variables were also identical except that additional data were collected on the specifics of manual therapy given at each visit.

Two sequential weekend workshops with a refresher session for each of the 31 physicians (developed and given to 9 physicians per workshop by 3 family physicians skilled in manual therapy) were implemented before the start of the clinical trial. The purpose was to train these physicians in quality care for low back pain (explained to patients as enhanced care—the control arm) and in standardized limited manual therapy (the main component of the intervention arm).¹³ The term “enhanced care” was developed to minimize the impression for patients during randomization that they might either receive something special (manual therapy) or just routine care—both options needed to appear to be special to reduce placebo bias.

Training for the enhanced low back pain care arm included physician education in (1) the directed history and physical examination using Agency for Health Care Policy and Research (AHCPR) guidelines,¹⁶ (2) review of the efficacy of imaging and laboratory testing, (3) review of the efficacy of treatment modalities, and (4) use of specially designed patient handouts emphasizing progressive exercises, daily activities, and early return to function.

Training for the limited manual therapy arm included the enhanced low back pain skills plus:

• manual therapy, consisting of: (1) principles of manual therapy and explanatory models, (2) instruction in motion testing, and (3) instruction in limited manual therapy skills (soft-tissue, muscle energy, and high-velocity low-amplitude techniques involving psoas and piriformis muscles—lumbar spine, lumbosacral junction, and sacroiliac joints)
• workshop training and demonstrated competence in low back care on simulated patients
• guidance and practice in integrating limited manual therapy into the office visit
• education and practice in recruiting patients and in the procedures of random assignment of those patients to the control (enhanced care) arm or the manual therapy arm

After training, the physicians returned to their practices and worked on their newly learned skill for approximately 3 months before enrolling patients. At an agreed time they began to enroll patients and randomized them to enhanced care or enhanced care plus limited manual therapy using a blinded method.

Analysis

Using the patients of the 13 physicians active in both the original cohort study and the subsequent randomized trial of limited manual therapy, we compared outcomes between 3 groups of patients: (1) those whose usual care was only observed in the earlier cohort study, (2) those receiving enhanced care (control arm) in the randomized trial, and (3) those receiving enhanced care plus manual therapy (intervention arm) in the randomized trial. The major variables included in the analyses were age, sex, education, household income, duration of low back pain episode for more than 2 weeks, presence of sciatica, workers’ compensation status, and the Work Adaptation, Partnership, Growth, Affection, and Resolve Survey (a measure of job satisfaction).¹⁶ In each of the studies, outcome measures from repeated interviews included data on functional status over time and pain levels. Data on satisfaction with care, return to work, and time to functional and complete recovery were obtained either at 8 weeks or when the patients were better. The main outcome measures were the Roland-Morris adaptation of the Sickness Impact Profile (a 23-item scale with high scores indicating significant dysfunction), patients’ report of being all better or functionally better, and the date they were able to return to performing their usual daily activities.^10,14 Patient satisfaction measures were based on the scale developed by Cherkin and colleagues.⁸ The patient was the unit of analysis.

Pearson’s chi-square was used when comparing the 3 patient groups by physician performance and patient satisfaction, adjusting for baseline differences. Linear modeling was used to examine the relationship of manual therapy to functional status (Roland-Morris score). Cox proportional hazard modeling was undertaken to identify survival curves of time to functional recovery. In all analyses, standard errors were corrected for any intraclass correlation due to nonindependence of patients seeing the same physician.¹⁷

Results

The 13 physicians cared for 120 patients in the observational study and 191 patients in the randomized trial [Figure 1]. In each of the studies very similar numbers of patients were seen by each physician. Within the 2 arms of the randomized trial of manual therapy, baseline characteristics were essentially the same [Table 1].

There were some differences in baseline characteristics between patients in the cohort study and the randomized trial. More patients in the randomized trial (41.4% vs 25%, P=.01) had significantly higher severe baseline dysfunction (Roland-Morris score=16-23) than in the cohort study. The mean baseline Roland Morris score was 10.0 for the cohort study patients compared with 12.5 for the manual therapy study patients (P=.03). There were more patients on workers’ compensation in the cohort study (35%) than in the manual therapy study (16.3%, P=.002), and fewer had been employed in the previous 3 months (80.8% vs 90.0%, P=.02).

Patients in both arms of the randomized manual therapy trial were significantly more satisfied than their counterparts in the earlier cohort study in terms of how their physician gave care in the clinical encounter and whether they received effective advice [Table 2]. Patients participating in the manual therapy trial were also more satisfied with their pain relief, their physicians’ overall treatment of back pain, and their ability to perform activities of daily living. Specific items of clinical performance where differences were noted included: the physician took a detailed history; gave useful advice on pain, preventive measures, sleeping, and sitting strategies; and provided back exercises. There were no differences in patient ratings of the physician’s ability to listen effectively, perform a careful physical examination, and explain the cause of their back pain. There were no differences in general health status between the cohort and manual therapy study patients.

When adjusted for baseline function, the presence of sciatica, duration of pain, employment status, workers’ compensation, and income of more than $20,000, mean functional outcomes measured by Roland-Morris scores at 2 weeks were 8.2 for the patients in the cohort study and 6.7 in the manual therapy trial (P=.03); at 4 weeks mean scores were 7.2 for the cohort and 5.2 for patients in the manual therapy trial (P=.02), and at 8 weeks scores were 6.7 and 3.6, respectively (P=.002). These were clinically significant differences showing that all patients in the clinical trial had lower functional disability levels during an 8-week period than patients of the same physicians in the cohort study.

After controlling for baseline Roland-Morris score, duration of low back pain, sciatica, employment status, workers’ compensation, and income more than $20,000, time to functional recovery reported by the patient (using Cox proportional hazard modeling) between the 3 groups of patients was as follows: (1) manual therapy + enhanced care versus cohort: hazard ratio (HR)=1.16; 95% confidence interval (CI), 0.85-1.58; (2) enhanced care alone versus cohort: HR=1.13; 95% CI, 0.82-1.54; and (3) manual therapy + enhanced care versus enhanced care alone: HR=1.03; 95% CI, 0.75-1.40. None of these HRs were significant [Figure 2].

Discussion

Data from patients of 13 physicians involved in an observational study of back care, followed by a randomized trial of the effect of additional clinical skills developed by hands-on training, provide an unusual opportunity to study patient outcomes and physician performance over time. Similar eligibility and exclusion criteria, data collection methods, and outcome measures were used in both studies, allowing us to directly compare the variables of interest.

After controlling for confounding factors and physician clustering effect, patients in the clinical trial of manual therapy had significantly more baseline dysfunction at the index visit but still recovered more rapidly by self-report. After workshop training for the physicians, the proportion of patients who reported effective evaluation and management of their back problem increased substantially.

There were no differences in the 2 studies in the proportions of patients reporting on how effectively their physician listened to them, explained causation, and discussed occupational issues. These latter activities were not specifically addressed in the training workshop, which concentrated on clinical evaluation, manual techniques, and issues of physical rehabilitation. One would expect that a general placebo effect on patients of the training would increase all parameters of their perceptions of care, so the workshop may have produced specific learning effects on the clinicians. Despite a trend favoring the group receiving care from the “trained” physicians, there were no significant differences in how patients perceived the quality of the physician’s physical examination of their back—an item that was particularly emphasized in the workshops. This aspect of physician performance was already highly rated in the cohort group and may have been less likely to show improvement, given the need to know what constitutes a superior examination technique.

The improved reported performances of physicians and patient outcomes were noted in both arms of the manual therapy trial, compared with those of patients in the earlier cohort study, though there was no difference in time to full functional recovery between the 2 studies. The inconsistency between outcomes (Roland-Morris scores and time to functional recovery) is probably explainable by the fact that they measure different patient perceptions of back problems—specific versus global recovery. This inconsistency of measures has been noted in other studies of low back pain interventions.¹⁸

The improved outcomes of patients in the randomized trial compared with those in the cohort may be because of specific elements of the study applicable to all patients or may have been due to unmeasured baseline differences. The patients in the randomized trial were more impaired at baseline, which would tend toward worse rather than better outcomes if severity was not completely controlled for. There are several possible explanations for these findings: (1) workshop training did improve physician knowledge and skills; (2) involvement of patients in a clinical trial in which an intervention (enhanced care) was given in both arms of the study (one also receiving manual therapy) could heighten the overall positive effect; (3) the clinical trial involved more visits (average=3.6) than with patients in the first study (1.3)—this could add significantly to patient satisfaction and perceptions of good care; and (4) the recruited physicians were a special group of interested and motivated individuals who by their nature would produce better outcomes in a clinical trial.

Limitations

There are limitations to our findings and conclusions. There were differences in exclusion criteria that might have reduced the number of unhealthy people recruited into the manual therapy trial compared with the cohort study. This could have led to better outcomes, though we doubt that these differences made much impact given the average age of the patients (40 years).

Although we adjusted for baseline differences (income, workers’ compensation, and employment status), we are not sure why these differences occurred. One possibility is that the rapid population and commercial growth and high employment rates that occurred in the state of North Carolina in the time between the 2 studies improved the economic characteristics of patients presenting to the physicians over time. It is also possible that patients with higher incomes and fewer employment difficulties would be more likely to rate physician communication and management more highly and improve more rapidly.

The global effect on clinician knowledge, skills, and performance of a 3-year span of evolving clinical practice and involvement in low back pain studies (other than participating in a training workshop) cannot be quantified. For example, improved performance and outcomes might have been related to the publication of the AHCPR back pain guidelines in 1994, approximately 6 months before the start of the manual therapy study.¹⁶ However, at the low back pain workshop (where only the AHCPR “red flags” were presented) the participants seemed to be only minimally aware of these guidelines.

If the improved outcomes noted in this study were mainly because of the passage of time rather than workshop training, this provides an interesting insight into how practice changes for the better.

Patient satisfaction with care has been shown to correlate with outcomes.^19,20 Deyo and Diehl suggested that dissatisfaction with care for low back pain was related to failure to obtain an adequate explanation from the physician, while Cherkin and colleagues proposed that lack of confidence in management and negative attitudes of clinicians might be key issues to be addressed in achieving better outcomes.^8-10,21,22 However, didactic training to remedy these problems did not appear to be very effective in improving satisfaction. Following up on these suggestions, Smucker and coworkers,¹² using the large North Carolina cohort study, showed that clinician self-confidence (allopathic and chiropractic physicians) did not predict patient outcomes but commented that communication, time spent with the patient, and manual evaluation and treatment skills might be important variables affecting outcome.¹²

The margin of differences in outcomes shown in our preintervention and postintervention analysis leads us to suggest that allopathic physicians using a brief systematic evaluation and hands-on regional physical examination, sound advice on pain management and prevention, and an increasingly active exercise program can modestly improve early patient functioning and satisfaction in acute low back pain. Whether training in limited manual therapy adds to this benefit is unclear and must be taken into account in relation to the current expansion of CME in manipulative skills for allopathic physicians. The costs and benefits of providing this training—with the possibility of needing one extra office visit or more to fully implement enhanced care—would need to be assessed.²³

Alternative or complementary approaches to medical care are gaining loyalty from patients and increasing interest from the allopathic health care community.^1-4 In particular, professional organizations in the areas of acupuncture and manual therapy are offering and expanding continuing medical education (CME) programs in these fields for allopathic physicians, though there are few published data on their effectiveness.^5,6

The direct impact of CME on patients and clinical practice has been little studied, particularly in relation to the treatment of low back pain.⁷ Cherkin and colleagues^8,9 undertook an evaluation of a didactic CME program on low back pain in 1991 by studying patient satisfaction and provider attitudes. It appeared that the patients of providers who professed greater confidence in managing low back pain were more satisfied with their care, though negative attitudes previously expressed by clinicians toward low back pain did not change significantly after CME. In a discussion of this study it was suggested that patients might be seeking information and practical guidance rather than a cure or empathy.¹⁰ However, the investigators did not study the effects of modifying physical examination and manual skills in the care of these patients, factors that might play an important role in outcomes.

Although greater patient satisfaction has been associated with chiropractic care (which emphasizes manual skills) than that given by primary care physicians, there appears to be no association of satisfaction with practitioner self-confidence or days to functional recovery of the patient.^11,12

We developed a workshop for generalist clinicians in the skills of assessment, limited manual therapy, and a graded exercise program, and in a randomized controlled trial evaluated clinician self-efficacy and patient outcomes for acute low back pain.^13,14 We demonstrated that allopathic generalist physicians could be effectively trained in limited manual therapy with self-reported increased competence in managing low back pain. The patients receiving therapy showed a trend toward feeling completely better more quickly but reported no greater satisfaction or objective functional improvement in terms of activities than patients in the control group who were receiving only high-quality conventional care through workshop training.¹⁴

Of 31 physicians recruited into the manual therapy trial, 13 had previously been involved in a cohort study of utilization and back care therapy given by 208 practitioners (115 primary care generalists) to 1633 patients (644 patients of primary care generalists).¹¹ We examined the outcomes of patients with low back pain from the practices of these 13 physicians before (data from the cohort study) and after an intensive hands-on training workshop (data from the manual therapy trial), using similar patient recruitment methods and evaluation instruments ([Figure 1]. Our hypothesis was that this training in manual and assessment skills would improve patient outcomes and satisfaction.

Methods

The initial cohort study was undertaken to examine the prevalence, care seeking, and outcomes of acute low back pain in the state of North Carolina. No interventions were undertaken in this study. Methods and measures used in its implementation have been described previously by Carey and coworkers.¹¹ Clinicians were randomly selected from medical and chiropractic licensure files (primary care generalists, chiropractic physicians, and orthopedic surgeons). To be included in the cohort study clinicians had to see ambulatory patients at least 50% of the time and provide first contact care for acute low back pain. Of the 208 clinicians from different disciplines recruited into the study, 115 were primary care physicians. During a 10-month period consecutive patients with acute or subacute low back pain (<10 weeks) were enrolled unless they had received previous care for the episode, had received previous back surgery, had a history of cancer, were pregnant, had no telephone, or were unable to speak English. Patients were contacted by telephone after the visit by staff members of the University of North Carolina Survey Research Unit, and interviews were undertaken at baseline, 2, 4, 8, 12, and 24 weeks.

These interviews included questions about details of the back pain episode, medications and other therapies used, tests performed, work and compensation status, demographic data, and income level. Outcome data included responses to the 23-item Roland-Morris Back Disability Questionnaire.¹⁵ We also asked when the patients considered they were able to perform their usual daily activities after the back pain. Patient satisfaction was assessed on how well the physician communicated, listened, gave information and explained the cause of back pain, whether a detailed history was taken and the back examined carefully, and if advice was given on pain management, prevention, and activities of sleeping and sitting (yes/no responses). Other satisfaction items (overall treatment, pain relief provided, and patient abilities to walk, socialize, and work) were rated on a 5-point Likert scale (poor, fair, good, very good, or excellent). This was subsequently adapted to a dichotomous response. Clinical and utilization data were obtained from charts in the physicians’ offices to allow validation of survey variables.

The randomized trial of the effectiveness of limited manual therapy was started in 1995, 12 months after the closure of the cohort study. Patients were recruited by 31 generalist physicians (13 from the earlier cohort study and 18 volunteers from the 630 physicians on the North Carolina physician master file). The same inclusion and exclusion criteria from the cohort study were used except that the acceptable age range was 21 to 65 (compared with 75 years) and patients had no osteopenia, severe arthritis, morbid obesity, or neurological deficits and had not received previous manual therapy by the physician. These additional exclusion criteria were necessary to avoid possible adverse effects of manual therapy in the presence of disease and to eliminate patient bias of a preference for manual therapy based on previous experience.

For each arm of the study, after the first office visit the identical telephone interview questions and schedule used in the cohort study were implemented for up to 8 weeks. Chart abstraction methods and variables were also identical except that additional data were collected on the specifics of manual therapy given at each visit.

Two sequential weekend workshops with a refresher session for each of the 31 physicians (developed and given to 9 physicians per workshop by 3 family physicians skilled in manual therapy) were implemented before the start of the clinical trial. The purpose was to train these physicians in quality care for low back pain (explained to patients as enhanced care—the control arm) and in standardized limited manual therapy (the main component of the intervention arm).¹³ The term “enhanced care” was developed to minimize the impression for patients during randomization that they might either receive something special (manual therapy) or just routine care—both options needed to appear to be special to reduce placebo bias.

Training for the enhanced low back pain care arm included physician education in (1) the directed history and physical examination using Agency for Health Care Policy and Research (AHCPR) guidelines,¹⁶ (2) review of the efficacy of imaging and laboratory testing, (3) review of the efficacy of treatment modalities, and (4) use of specially designed patient handouts emphasizing progressive exercises, daily activities, and early return to function.

Training for the limited manual therapy arm included the enhanced low back pain skills plus:

• manual therapy, consisting of: (1) principles of manual therapy and explanatory models, (2) instruction in motion testing, and (3) instruction in limited manual therapy skills (soft-tissue, muscle energy, and high-velocity low-amplitude techniques involving psoas and piriformis muscles—lumbar spine, lumbosacral junction, and sacroiliac joints)
• workshop training and demonstrated competence in low back care on simulated patients
• guidance and practice in integrating limited manual therapy into the office visit
• education and practice in recruiting patients and in the procedures of random assignment of those patients to the control (enhanced care) arm or the manual therapy arm

After training, the physicians returned to their practices and worked on their newly learned skill for approximately 3 months before enrolling patients. At an agreed time they began to enroll patients and randomized them to enhanced care or enhanced care plus limited manual therapy using a blinded method.

Analysis

Using the patients of the 13 physicians active in both the original cohort study and the subsequent randomized trial of limited manual therapy, we compared outcomes between 3 groups of patients: (1) those whose usual care was only observed in the earlier cohort study, (2) those receiving enhanced care (control arm) in the randomized trial, and (3) those receiving enhanced care plus manual therapy (intervention arm) in the randomized trial. The major variables included in the analyses were age, sex, education, household income, duration of low back pain episode for more than 2 weeks, presence of sciatica, workers’ compensation status, and the Work Adaptation, Partnership, Growth, Affection, and Resolve Survey (a measure of job satisfaction).¹⁶ In each of the studies, outcome measures from repeated interviews included data on functional status over time and pain levels. Data on satisfaction with care, return to work, and time to functional and complete recovery were obtained either at 8 weeks or when the patients were better. The main outcome measures were the Roland-Morris adaptation of the Sickness Impact Profile (a 23-item scale with high scores indicating significant dysfunction), patients’ report of being all better or functionally better, and the date they were able to return to performing their usual daily activities.^10,14 Patient satisfaction measures were based on the scale developed by Cherkin and colleagues.⁸ The patient was the unit of analysis.

Pearson’s chi-square was used when comparing the 3 patient groups by physician performance and patient satisfaction, adjusting for baseline differences. Linear modeling was used to examine the relationship of manual therapy to functional status (Roland-Morris score). Cox proportional hazard modeling was undertaken to identify survival curves of time to functional recovery. In all analyses, standard errors were corrected for any intraclass correlation due to nonindependence of patients seeing the same physician.¹⁷

Results

The 13 physicians cared for 120 patients in the observational study and 191 patients in the randomized trial [Figure 1]. In each of the studies very similar numbers of patients were seen by each physician. Within the 2 arms of the randomized trial of manual therapy, baseline characteristics were essentially the same [Table 1].

There were some differences in baseline characteristics between patients in the cohort study and the randomized trial. More patients in the randomized trial (41.4% vs 25%, P=.01) had significantly higher severe baseline dysfunction (Roland-Morris score=16-23) than in the cohort study. The mean baseline Roland Morris score was 10.0 for the cohort study patients compared with 12.5 for the manual therapy study patients (P=.03). There were more patients on workers’ compensation in the cohort study (35%) than in the manual therapy study (16.3%, P=.002), and fewer had been employed in the previous 3 months (80.8% vs 90.0%, P=.02).

Patients in both arms of the randomized manual therapy trial were significantly more satisfied than their counterparts in the earlier cohort study in terms of how their physician gave care in the clinical encounter and whether they received effective advice [Table 2]. Patients participating in the manual therapy trial were also more satisfied with their pain relief, their physicians’ overall treatment of back pain, and their ability to perform activities of daily living. Specific items of clinical performance where differences were noted included: the physician took a detailed history; gave useful advice on pain, preventive measures, sleeping, and sitting strategies; and provided back exercises. There were no differences in patient ratings of the physician’s ability to listen effectively, perform a careful physical examination, and explain the cause of their back pain. There were no differences in general health status between the cohort and manual therapy study patients.

When adjusted for baseline function, the presence of sciatica, duration of pain, employment status, workers’ compensation, and income of more than $20,000, mean functional outcomes measured by Roland-Morris scores at 2 weeks were 8.2 for the patients in the cohort study and 6.7 in the manual therapy trial (P=.03); at 4 weeks mean scores were 7.2 for the cohort and 5.2 for patients in the manual therapy trial (P=.02), and at 8 weeks scores were 6.7 and 3.6, respectively (P=.002). These were clinically significant differences showing that all patients in the clinical trial had lower functional disability levels during an 8-week period than patients of the same physicians in the cohort study.

After controlling for baseline Roland-Morris score, duration of low back pain, sciatica, employment status, workers’ compensation, and income more than $20,000, time to functional recovery reported by the patient (using Cox proportional hazard modeling) between the 3 groups of patients was as follows: (1) manual therapy + enhanced care versus cohort: hazard ratio (HR)=1.16; 95% confidence interval (CI), 0.85-1.58; (2) enhanced care alone versus cohort: HR=1.13; 95% CI, 0.82-1.54; and (3) manual therapy + enhanced care versus enhanced care alone: HR=1.03; 95% CI, 0.75-1.40. None of these HRs were significant [Figure 2].

Discussion

Data from patients of 13 physicians involved in an observational study of back care, followed by a randomized trial of the effect of additional clinical skills developed by hands-on training, provide an unusual opportunity to study patient outcomes and physician performance over time. Similar eligibility and exclusion criteria, data collection methods, and outcome measures were used in both studies, allowing us to directly compare the variables of interest.

After controlling for confounding factors and physician clustering effect, patients in the clinical trial of manual therapy had significantly more baseline dysfunction at the index visit but still recovered more rapidly by self-report. After workshop training for the physicians, the proportion of patients who reported effective evaluation and management of their back problem increased substantially.

There were no differences in the 2 studies in the proportions of patients reporting on how effectively their physician listened to them, explained causation, and discussed occupational issues. These latter activities were not specifically addressed in the training workshop, which concentrated on clinical evaluation, manual techniques, and issues of physical rehabilitation. One would expect that a general placebo effect on patients of the training would increase all parameters of their perceptions of care, so the workshop may have produced specific learning effects on the clinicians. Despite a trend favoring the group receiving care from the “trained” physicians, there were no significant differences in how patients perceived the quality of the physician’s physical examination of their back—an item that was particularly emphasized in the workshops. This aspect of physician performance was already highly rated in the cohort group and may have been less likely to show improvement, given the need to know what constitutes a superior examination technique.

The improved reported performances of physicians and patient outcomes were noted in both arms of the manual therapy trial, compared with those of patients in the earlier cohort study, though there was no difference in time to full functional recovery between the 2 studies. The inconsistency between outcomes (Roland-Morris scores and time to functional recovery) is probably explainable by the fact that they measure different patient perceptions of back problems—specific versus global recovery. This inconsistency of measures has been noted in other studies of low back pain interventions.¹⁸

The improved outcomes of patients in the randomized trial compared with those in the cohort may be because of specific elements of the study applicable to all patients or may have been due to unmeasured baseline differences. The patients in the randomized trial were more impaired at baseline, which would tend toward worse rather than better outcomes if severity was not completely controlled for. There are several possible explanations for these findings: (1) workshop training did improve physician knowledge and skills; (2) involvement of patients in a clinical trial in which an intervention (enhanced care) was given in both arms of the study (one also receiving manual therapy) could heighten the overall positive effect; (3) the clinical trial involved more visits (average=3.6) than with patients in the first study (1.3)—this could add significantly to patient satisfaction and perceptions of good care; and (4) the recruited physicians were a special group of interested and motivated individuals who by their nature would produce better outcomes in a clinical trial.

Limitations

There are limitations to our findings and conclusions. There were differences in exclusion criteria that might have reduced the number of unhealthy people recruited into the manual therapy trial compared with the cohort study. This could have led to better outcomes, though we doubt that these differences made much impact given the average age of the patients (40 years).

Although we adjusted for baseline differences (income, workers’ compensation, and employment status), we are not sure why these differences occurred. One possibility is that the rapid population and commercial growth and high employment rates that occurred in the state of North Carolina in the time between the 2 studies improved the economic characteristics of patients presenting to the physicians over time. It is also possible that patients with higher incomes and fewer employment difficulties would be more likely to rate physician communication and management more highly and improve more rapidly.

The global effect on clinician knowledge, skills, and performance of a 3-year span of evolving clinical practice and involvement in low back pain studies (other than participating in a training workshop) cannot be quantified. For example, improved performance and outcomes might have been related to the publication of the AHCPR back pain guidelines in 1994, approximately 6 months before the start of the manual therapy study.¹⁶ However, at the low back pain workshop (where only the AHCPR “red flags” were presented) the participants seemed to be only minimally aware of these guidelines.

If the improved outcomes noted in this study were mainly because of the passage of time rather than workshop training, this provides an interesting insight into how practice changes for the better.

Patient satisfaction with care has been shown to correlate with outcomes.^19,20 Deyo and Diehl suggested that dissatisfaction with care for low back pain was related to failure to obtain an adequate explanation from the physician, while Cherkin and colleagues proposed that lack of confidence in management and negative attitudes of clinicians might be key issues to be addressed in achieving better outcomes.^8-10,21,22 However, didactic training to remedy these problems did not appear to be very effective in improving satisfaction. Following up on these suggestions, Smucker and coworkers,¹² using the large North Carolina cohort study, showed that clinician self-confidence (allopathic and chiropractic physicians) did not predict patient outcomes but commented that communication, time spent with the patient, and manual evaluation and treatment skills might be important variables affecting outcome.¹²

The margin of differences in outcomes shown in our preintervention and postintervention analysis leads us to suggest that allopathic physicians using a brief systematic evaluation and hands-on regional physical examination, sound advice on pain management and prevention, and an increasingly active exercise program can modestly improve early patient functioning and satisfaction in acute low back pain. Whether training in limited manual therapy adds to this benefit is unclear and must be taken into account in relation to the current expansion of CME in manipulative skills for allopathic physicians. The costs and benefits of providing this training—with the possibility of needing one extra office visit or more to fully implement enhanced care—would need to be assessed.²³

A part from symptoms caused by vertebral disk injury, the scientific evidence for the specific causation and effective treatment of low back problems is relatively weak. Clinicians who wish to adhere to evidence-based practice when treating persistent low back pain are faced with a limited number of useful interventions: short-term therapy with muscle relaxants and analgesics, and encouragement to return to daily routines as quickly as possible.^1-3

Though doubt has been cast on the real existence of subtypes or syndromes of low back pain, our clinical observation and experience suggest that a fibro-fatty nodule (“back mouse”) may be an identifiable and remediable cause of acute or chronic low back pain.^4,5 Given the extent of the costs and suffering caused by low back pain, effective therapy for even a few cases of recurrent or chronic pain would be helpful. We describe 2 patients for whom back mice were the likely cause of low back pain and were associated with unusual symptoms and signs, masquerading as other clinical problems. In both cases, the full medical records from the Family Practice Center and University of North Carolina hospitals were available for evaluation.

Methods and results

Bilateral Trochanteric Bursitis

In 1985 Ms C, a 53-year-old nursing aide, developed typical signs and symptoms of trochanteric bursitis following a vaginal hysterectomy. She also suffered from mild hypertension and chronic depression. The hip pain was intermittent and would affect one side and then the other, often radiating down the legs and limiting her ability to walk. Examination revealed marked tenderness to palpation over the greater trochanter in either hip area. There were no clear precipitating factors.

She was first treated with a variety of nonsteroidal anti-inflammatory agents, with little effect. Subsequently, she received physical therapy including ultrasound, exercise, and cushioned shoes, all of which produced only temporary relief. Because of the chronic pain antidepressants were also tried, which improved her depression but provided minimal improvement for the hip problem.

In 1991, orthopedic evaluation confirmed the findings of relapsing bilateral trochanteric bursitis with an otherwise normal physical examination. Lumbosacral spine and hip radiographs showed only mild degeneration of the L4/5 vertebral disk. The greatest relief for the patient came from injections of lidocaine hydrochloride and methylprednisolone acetate directly into each bursa, but relief lasted only a few weeks after each injection. They had to be repeated on a regular basis. She also needed acetaminophen and oxycodone twice daily to help control the pain, and in 1995 she applied for disability.

At that time, the orthopedic specialist discharged her back to her family physician with a diagnosis of chronic trochanteric bursitis for which no other treatment could be offered. In 1997 another orthopedic consultation led to the same opinion, based on typical symptoms and clinical findings. In 1998, during a discussion of the lack of treatment options for this chronic problem, it was suggested that the symptoms could be secondary to a lower back problem and a careful soft tissue examination might be of value. Detailed examination revealed 2 long rubbery and tender fibro-fatty nodules, each one lying on an iliac crest (right side=3 cm by l cm; left side=6 cm by l cm) These findings correlated with previous descriptions of fibro-fatty nodules in the back region.^4,7

Repeated testing using firm palpation of these nodules reproduced the pain over each greater trochanteric area where the patient had experienced pain in the past. Each nodule was treated with multiple puncture technique (6 to 8 punctures of the fibrous capsule of the nodule) and injected with 3 cc of lidocaine hydrochloride and 40 mg methylprednisolone acetate.^4,5 There was immediate and complete relief of the clinical symptoms and signs. Five months after the injections there has been no recurrence of the clinical characteristics of trochanteric bursitis, though there have been other symptoms of lumbosacral pain.

An Abdominal Emergency

In 1997 Ms W, a 35-year-old with type 2 diabetes (controlled by diet and exercise) was working as a nurse on the pediatric ward. She came to the urgent care clinic at the Family Practice Center with symptoms of mild low back pain and right-sided lower abdominal pain which were associated with dysuria and frequency of urination during the previous 2 months. She had suffered an episode of low back pain 2 years earlier. Her urine showed a mildly positive leukocyte esterase test and a trace of protein, and she was given a course of trimethoprim.

Ten days later she returned reporting that the abdominal pain had become much worse, particularly when sitting and lying down, and it kept her awake at night. She complained of a feeling of fullness in the right lower quadrant of the abdomen. There were no changes in her bowel habit, and she had no fever, nausea, or anorexia. She was taking maximum doses of ibuprofen and acetaminophen for the pain. A repeat urinalysis was normal. She had previously had a hysterectomy and appendectomy, as well as polycystic ovaries, but the results of a pelvic examination were normal. Examination of the abdomen revealed normal bowel sounds and some tenderness in the right lower quadrant, close to the superior iliac spine. Because of her history of persistent back pain and a lack of explanation for her abdominal symptoms, x-rays of the lumbosacral spine and pelvis were ordered.

When she was seen again 2 days later, the abdominal pain had become much more severe. It was sharp, intermittent, not colicky, and traveled down into the groin and right anterior thigh. There was considerably less pain when she was standing. She had normal bowel sounds but was again acutely sensitive to palpation in the lower abdomen just above the anterior superior iliac crest. Assessment for acute abdominal pain included an electrolyte panel and complete blood count, which were normal except for a white blood count of 11,200. The lumbar and pelvic radiologic studies showed mild degeneration of the hip joints and some spurring of the inferior aspect of both sacroiliac joints.

With a working diagnosis of lower abdominal abscess, she was referred to the emergency department to be seen by the family medicine inpatient team. A computed tomography scan of the abdomen and pelvis was normal, showing only a small ovarian cyst on the left ovary. However, a repeat white blood count (several hours later) was 13,100. A surgical consultation was requested, but the surgeon found no evidence of an acute abdominal process, giving his opinion that this was a musculoskeletal problem.

At the suggestion of one of the family medicine faculty a more detailed examination of the sacroiliac joints was performed, and the resident found significant point tenderness over the right sacroiliac joint. Deep palpation of this joint area also produced pain radiating to the right inguinal region. It was felt that the acute abdominal problem might be caused by referred pain from the sacroiliac joint. The patient received an injection of 60 mg ketorolac tromethamine, which produced considerable relief, and she was sent home. However, there was no clear explanation for the 2 occasions of elevated white blood cell count.

At follow-up 10 days later the abdominal pain had subsided, but she was complaining of much more pain in the right lower back with referral down the front of her thighs. There was still tenderness over the right sacroiliac joint, and she was sent to a physical therapist for evaluation and treatment. During her first visit to the physical therapist, in addition to the low back symptoms she again reported increasing right lower abdominal pain that was worse when sitting, better when standing. Careful examination revealed an extremely tender 3 cm long, partly mobile, fibro-fatty nodule along the mid-region of the right iliac crest, approximately 4 inches lateral to the spinous process of the lumbar vertebra. Repeated firm, direct pressure on this nodule made the patient cry and reproduced the right lower abdominal symptoms.

Following injection with multiple puncture technique, lidocaine hydrochloride 3 cc and methyprednisolone acetate 40 mg, the patient experienced immediate pain relief with no more abdominal symptoms and no difficulty in sitting or lying down. Since that time (2 years ago), there has been no recurrence of these symptoms. Although the cause of the abdominal pain might have been a polycystic ovary, the workup did not support this conclusion and revealed no other obvious cause for the severe symptoms. Injecting a painful nodular swelling in the lower back that fitted the characteristics of previously described fibro-fatty nodules provided immediate relief of the pain, suggesting a possible association with the anterior abdominal symptoms.

Discussion

Do Back Mice Really Exist?

There is general agreement in a number of published case series from various rheumatologic and hospital populations that these nodules do exist, with an estimated prevalence of 15% in the general population.^5,7 These studies all report characteristic locations and clinical findings of a rubbery, well-defined, often mobile, round or oval swelling in the deep subcutaneous tissues. Though these can be painful, they never show evidence of infection and are frequently asymptomatic. The only other frequently found nodules with a similar anatomical location are lipomas (more superficial and soft to palpation) and sebaceous cysts (more superficial and usually circular).

Why Would Back Mice Masquerade as Other Conditions?

It is difficult to postulate a direct mechanical effect in which a low back nodule would produce pain at a distant location, so it is more likely that this is some form of referred pain. The authors of previous studies have reported that these nodules may mimic sciatic nerve root compression and lead to a diagnosis of vertebral disk prolapse.^6-8 The 2 cases we report appear to show a pattern different from that of the sciatic nerve. The first case is similar to data reported by Collee and colleagues⁹ in a study of hospital and primary care patients suffering from low back pain. They found that a substantial proportion of patients (45% and 25%, respectively) with low back pain also complained of greater trochanteric pain syndrome. There may be a specific referral pathway linking the 2 areas. It is more difficult to explain an association between a back mouse and the symptoms of abdominal pain in the second case. One possible mechanism could be a referral pattern, well reported in the literature, that comes from musculoskeletal structures (fascia, muscle, fibrous tissue, tendons) and follows sclerotomal distribution rather than the segmental dermatomes shown in most anatomical texts.^10-12 There is ample evidence that anterior abdominal pain can be referred from musculoskeletal elements in the low back region and can be quite severe.¹³ Referred pain from the fibrous capsule surrounding fibro-fatty nodules might explain the distant symptoms and signs in our 2 cases.

Where Do Back Mice Come From?

Pathologic studies show that these nodules consist of a fibrous capsule containing fat divided by fibrous septa and some fine blood vessels and nerve fibers, and they usually have a stalk connecting them to the tissues below the deep fascial layers.⁸ It has been suggested that these nodules and their stalks are formed by extrusion through the neurovascular foramina in the deep fascia as a result of mechanical stresses.

Why Would Back Mice Cause Pain?

The answer to this is not known. Nodules that have been examined after surgery have not shown evidence of inflammation as a cause of pain, though nerve fibers are found in the fibrous capsule. In our experience, the immediate relief of pain frequently produced by multiple needle puncture, compared with poor relief with a single puncture, suggests that the pain might be caused by raised intranodular pressure.⁶

Why Would Injections Relieve Pain Caused by Back Mice?

A recent long-term follow-up study of 35 patients showed that 89% had lasting relief. Generally, placebo effects from injections do not exceed 50% improvement.⁶ If lidocaine hydrochloride is used, its possible beneficial effects may come from washing out irritant chemicals (substance P) from the area, from local vasodilation that facilitates the removal of metabolites, or from the interruption of the neural feedback mechanism.¹³ However, the local anesthetic effect is too short to explain lasting relief, and a randomized controlled study of injection therapy of the iliac crest syndrome showed no difference in pain outcome between lidocaine hydrochloride and saline.¹⁴ This would tend to support the possibility that multiple puncture, rather than the injected material, is effective because it lessens the tension of the innervated fibrous capsule. Does Injection Treatment of the Back Mouse Really Work? There have been no randomized controlled trials and, until recently, no published long-term follow-up studies of treatment. It is not clear if multiple puncture of the nodule followed by deep massage alone is effective or whether the addition of local anesthetic and steroid improves outcome.

Conclusions

Until a rigorous study demonstrates the reliability and reproducibility of the clinical diagnosis of the back mouse and the effectiveness of treatment in a randomized controlled trial, our best advice for physicians, based purely on clinical and biased observation, is to consider the back mouse when atypical and unaccountable symptoms and signs are found in the lower abdomen, inguinal region, or legs.

Acknowledgements

We are grateful to Barry R. Howes, PT, and Robert E. Gwyther for guidance in the preparation of this report.

A part from symptoms caused by vertebral disk injury, the scientific evidence for the specific causation and effective treatment of low back problems is relatively weak. Clinicians who wish to adhere to evidence-based practice when treating persistent low back pain are faced with a limited number of useful interventions: short-term therapy with muscle relaxants and analgesics, and encouragement to return to daily routines as quickly as possible.^1-3

Though doubt has been cast on the real existence of subtypes or syndromes of low back pain, our clinical observation and experience suggest that a fibro-fatty nodule (“back mouse”) may be an identifiable and remediable cause of acute or chronic low back pain.^4,5 Given the extent of the costs and suffering caused by low back pain, effective therapy for even a few cases of recurrent or chronic pain would be helpful. We describe 2 patients for whom back mice were the likely cause of low back pain and were associated with unusual symptoms and signs, masquerading as other clinical problems. In both cases, the full medical records from the Family Practice Center and University of North Carolina hospitals were available for evaluation.

Methods and results

Bilateral Trochanteric Bursitis

In 1985 Ms C, a 53-year-old nursing aide, developed typical signs and symptoms of trochanteric bursitis following a vaginal hysterectomy. She also suffered from mild hypertension and chronic depression. The hip pain was intermittent and would affect one side and then the other, often radiating down the legs and limiting her ability to walk. Examination revealed marked tenderness to palpation over the greater trochanter in either hip area. There were no clear precipitating factors.

She was first treated with a variety of nonsteroidal anti-inflammatory agents, with little effect. Subsequently, she received physical therapy including ultrasound, exercise, and cushioned shoes, all of which produced only temporary relief. Because of the chronic pain antidepressants were also tried, which improved her depression but provided minimal improvement for the hip problem.

In 1991, orthopedic evaluation confirmed the findings of relapsing bilateral trochanteric bursitis with an otherwise normal physical examination. Lumbosacral spine and hip radiographs showed only mild degeneration of the L4/5 vertebral disk. The greatest relief for the patient came from injections of lidocaine hydrochloride and methylprednisolone acetate directly into each bursa, but relief lasted only a few weeks after each injection. They had to be repeated on a regular basis. She also needed acetaminophen and oxycodone twice daily to help control the pain, and in 1995 she applied for disability.

At that time, the orthopedic specialist discharged her back to her family physician with a diagnosis of chronic trochanteric bursitis for which no other treatment could be offered. In 1997 another orthopedic consultation led to the same opinion, based on typical symptoms and clinical findings. In 1998, during a discussion of the lack of treatment options for this chronic problem, it was suggested that the symptoms could be secondary to a lower back problem and a careful soft tissue examination might be of value. Detailed examination revealed 2 long rubbery and tender fibro-fatty nodules, each one lying on an iliac crest (right side=3 cm by l cm; left side=6 cm by l cm) These findings correlated with previous descriptions of fibro-fatty nodules in the back region.^4,7

Repeated testing using firm palpation of these nodules reproduced the pain over each greater trochanteric area where the patient had experienced pain in the past. Each nodule was treated with multiple puncture technique (6 to 8 punctures of the fibrous capsule of the nodule) and injected with 3 cc of lidocaine hydrochloride and 40 mg methylprednisolone acetate.^4,5 There was immediate and complete relief of the clinical symptoms and signs. Five months after the injections there has been no recurrence of the clinical characteristics of trochanteric bursitis, though there have been other symptoms of lumbosacral pain.

An Abdominal Emergency

In 1997 Ms W, a 35-year-old with type 2 diabetes (controlled by diet and exercise) was working as a nurse on the pediatric ward. She came to the urgent care clinic at the Family Practice Center with symptoms of mild low back pain and right-sided lower abdominal pain which were associated with dysuria and frequency of urination during the previous 2 months. She had suffered an episode of low back pain 2 years earlier. Her urine showed a mildly positive leukocyte esterase test and a trace of protein, and she was given a course of trimethoprim.

Ten days later she returned reporting that the abdominal pain had become much worse, particularly when sitting and lying down, and it kept her awake at night. She complained of a feeling of fullness in the right lower quadrant of the abdomen. There were no changes in her bowel habit, and she had no fever, nausea, or anorexia. She was taking maximum doses of ibuprofen and acetaminophen for the pain. A repeat urinalysis was normal. She had previously had a hysterectomy and appendectomy, as well as polycystic ovaries, but the results of a pelvic examination were normal. Examination of the abdomen revealed normal bowel sounds and some tenderness in the right lower quadrant, close to the superior iliac spine. Because of her history of persistent back pain and a lack of explanation for her abdominal symptoms, x-rays of the lumbosacral spine and pelvis were ordered.

When she was seen again 2 days later, the abdominal pain had become much more severe. It was sharp, intermittent, not colicky, and traveled down into the groin and right anterior thigh. There was considerably less pain when she was standing. She had normal bowel sounds but was again acutely sensitive to palpation in the lower abdomen just above the anterior superior iliac crest. Assessment for acute abdominal pain included an electrolyte panel and complete blood count, which were normal except for a white blood count of 11,200. The lumbar and pelvic radiologic studies showed mild degeneration of the hip joints and some spurring of the inferior aspect of both sacroiliac joints.

With a working diagnosis of lower abdominal abscess, she was referred to the emergency department to be seen by the family medicine inpatient team. A computed tomography scan of the abdomen and pelvis was normal, showing only a small ovarian cyst on the left ovary. However, a repeat white blood count (several hours later) was 13,100. A surgical consultation was requested, but the surgeon found no evidence of an acute abdominal process, giving his opinion that this was a musculoskeletal problem.

At the suggestion of one of the family medicine faculty a more detailed examination of the sacroiliac joints was performed, and the resident found significant point tenderness over the right sacroiliac joint. Deep palpation of this joint area also produced pain radiating to the right inguinal region. It was felt that the acute abdominal problem might be caused by referred pain from the sacroiliac joint. The patient received an injection of 60 mg ketorolac tromethamine, which produced considerable relief, and she was sent home. However, there was no clear explanation for the 2 occasions of elevated white blood cell count.

At follow-up 10 days later the abdominal pain had subsided, but she was complaining of much more pain in the right lower back with referral down the front of her thighs. There was still tenderness over the right sacroiliac joint, and she was sent to a physical therapist for evaluation and treatment. During her first visit to the physical therapist, in addition to the low back symptoms she again reported increasing right lower abdominal pain that was worse when sitting, better when standing. Careful examination revealed an extremely tender 3 cm long, partly mobile, fibro-fatty nodule along the mid-region of the right iliac crest, approximately 4 inches lateral to the spinous process of the lumbar vertebra. Repeated firm, direct pressure on this nodule made the patient cry and reproduced the right lower abdominal symptoms.

Following injection with multiple puncture technique, lidocaine hydrochloride 3 cc and methyprednisolone acetate 40 mg, the patient experienced immediate pain relief with no more abdominal symptoms and no difficulty in sitting or lying down. Since that time (2 years ago), there has been no recurrence of these symptoms. Although the cause of the abdominal pain might have been a polycystic ovary, the workup did not support this conclusion and revealed no other obvious cause for the severe symptoms. Injecting a painful nodular swelling in the lower back that fitted the characteristics of previously described fibro-fatty nodules provided immediate relief of the pain, suggesting a possible association with the anterior abdominal symptoms.

Discussion

Do Back Mice Really Exist?

There is general agreement in a number of published case series from various rheumatologic and hospital populations that these nodules do exist, with an estimated prevalence of 15% in the general population.^5,7 These studies all report characteristic locations and clinical findings of a rubbery, well-defined, often mobile, round or oval swelling in the deep subcutaneous tissues. Though these can be painful, they never show evidence of infection and are frequently asymptomatic. The only other frequently found nodules with a similar anatomical location are lipomas (more superficial and soft to palpation) and sebaceous cysts (more superficial and usually circular).

Why Would Back Mice Masquerade as Other Conditions?

It is difficult to postulate a direct mechanical effect in which a low back nodule would produce pain at a distant location, so it is more likely that this is some form of referred pain. The authors of previous studies have reported that these nodules may mimic sciatic nerve root compression and lead to a diagnosis of vertebral disk prolapse.^6-8 The 2 cases we report appear to show a pattern different from that of the sciatic nerve. The first case is similar to data reported by Collee and colleagues⁹ in a study of hospital and primary care patients suffering from low back pain. They found that a substantial proportion of patients (45% and 25%, respectively) with low back pain also complained of greater trochanteric pain syndrome. There may be a specific referral pathway linking the 2 areas. It is more difficult to explain an association between a back mouse and the symptoms of abdominal pain in the second case. One possible mechanism could be a referral pattern, well reported in the literature, that comes from musculoskeletal structures (fascia, muscle, fibrous tissue, tendons) and follows sclerotomal distribution rather than the segmental dermatomes shown in most anatomical texts.^10-12 There is ample evidence that anterior abdominal pain can be referred from musculoskeletal elements in the low back region and can be quite severe.¹³ Referred pain from the fibrous capsule surrounding fibro-fatty nodules might explain the distant symptoms and signs in our 2 cases.

Where Do Back Mice Come From?

Pathologic studies show that these nodules consist of a fibrous capsule containing fat divided by fibrous septa and some fine blood vessels and nerve fibers, and they usually have a stalk connecting them to the tissues below the deep fascial layers.⁸ It has been suggested that these nodules and their stalks are formed by extrusion through the neurovascular foramina in the deep fascia as a result of mechanical stresses.

Why Would Back Mice Cause Pain?

The answer to this is not known. Nodules that have been examined after surgery have not shown evidence of inflammation as a cause of pain, though nerve fibers are found in the fibrous capsule. In our experience, the immediate relief of pain frequently produced by multiple needle puncture, compared with poor relief with a single puncture, suggests that the pain might be caused by raised intranodular pressure.⁶

Why Would Injections Relieve Pain Caused by Back Mice?

A recent long-term follow-up study of 35 patients showed that 89% had lasting relief. Generally, placebo effects from injections do not exceed 50% improvement.⁶ If lidocaine hydrochloride is used, its possible beneficial effects may come from washing out irritant chemicals (substance P) from the area, from local vasodilation that facilitates the removal of metabolites, or from the interruption of the neural feedback mechanism.¹³ However, the local anesthetic effect is too short to explain lasting relief, and a randomized controlled study of injection therapy of the iliac crest syndrome showed no difference in pain outcome between lidocaine hydrochloride and saline.¹⁴ This would tend to support the possibility that multiple puncture, rather than the injected material, is effective because it lessens the tension of the innervated fibrous capsule. Does Injection Treatment of the Back Mouse Really Work? There have been no randomized controlled trials and, until recently, no published long-term follow-up studies of treatment. It is not clear if multiple puncture of the nodule followed by deep massage alone is effective or whether the addition of local anesthetic and steroid improves outcome.

Conclusions

Until a rigorous study demonstrates the reliability and reproducibility of the clinical diagnosis of the back mouse and the effectiveness of treatment in a randomized controlled trial, our best advice for physicians, based purely on clinical and biased observation, is to consider the back mouse when atypical and unaccountable symptoms and signs are found in the lower abdomen, inguinal region, or legs.

Acknowledgements

We are grateful to Barry R. Howes, PT, and Robert E. Gwyther for guidance in the preparation of this report.

A part from symptoms caused by vertebral disk injury, the scientific evidence for the specific causation and effective treatment of low back problems is relatively weak. Clinicians who wish to adhere to evidence-based practice when treating persistent low back pain are faced with a limited number of useful interventions: short-term therapy with muscle relaxants and analgesics, and encouragement to return to daily routines as quickly as possible.^1-3

Though doubt has been cast on the real existence of subtypes or syndromes of low back pain, our clinical observation and experience suggest that a fibro-fatty nodule (“back mouse”) may be an identifiable and remediable cause of acute or chronic low back pain.^4,5 Given the extent of the costs and suffering caused by low back pain, effective therapy for even a few cases of recurrent or chronic pain would be helpful. We describe 2 patients for whom back mice were the likely cause of low back pain and were associated with unusual symptoms and signs, masquerading as other clinical problems. In both cases, the full medical records from the Family Practice Center and University of North Carolina hospitals were available for evaluation.

Methods and results

Bilateral Trochanteric Bursitis

In 1985 Ms C, a 53-year-old nursing aide, developed typical signs and symptoms of trochanteric bursitis following a vaginal hysterectomy. She also suffered from mild hypertension and chronic depression. The hip pain was intermittent and would affect one side and then the other, often radiating down the legs and limiting her ability to walk. Examination revealed marked tenderness to palpation over the greater trochanter in either hip area. There were no clear precipitating factors.

She was first treated with a variety of nonsteroidal anti-inflammatory agents, with little effect. Subsequently, she received physical therapy including ultrasound, exercise, and cushioned shoes, all of which produced only temporary relief. Because of the chronic pain antidepressants were also tried, which improved her depression but provided minimal improvement for the hip problem.

In 1991, orthopedic evaluation confirmed the findings of relapsing bilateral trochanteric bursitis with an otherwise normal physical examination. Lumbosacral spine and hip radiographs showed only mild degeneration of the L4/5 vertebral disk. The greatest relief for the patient came from injections of lidocaine hydrochloride and methylprednisolone acetate directly into each bursa, but relief lasted only a few weeks after each injection. They had to be repeated on a regular basis. She also needed acetaminophen and oxycodone twice daily to help control the pain, and in 1995 she applied for disability.

At that time, the orthopedic specialist discharged her back to her family physician with a diagnosis of chronic trochanteric bursitis for which no other treatment could be offered. In 1997 another orthopedic consultation led to the same opinion, based on typical symptoms and clinical findings. In 1998, during a discussion of the lack of treatment options for this chronic problem, it was suggested that the symptoms could be secondary to a lower back problem and a careful soft tissue examination might be of value. Detailed examination revealed 2 long rubbery and tender fibro-fatty nodules, each one lying on an iliac crest (right side=3 cm by l cm; left side=6 cm by l cm) These findings correlated with previous descriptions of fibro-fatty nodules in the back region.^4,7

Repeated testing using firm palpation of these nodules reproduced the pain over each greater trochanteric area where the patient had experienced pain in the past. Each nodule was treated with multiple puncture technique (6 to 8 punctures of the fibrous capsule of the nodule) and injected with 3 cc of lidocaine hydrochloride and 40 mg methylprednisolone acetate.^4,5 There was immediate and complete relief of the clinical symptoms and signs. Five months after the injections there has been no recurrence of the clinical characteristics of trochanteric bursitis, though there have been other symptoms of lumbosacral pain.

An Abdominal Emergency

In 1997 Ms W, a 35-year-old with type 2 diabetes (controlled by diet and exercise) was working as a nurse on the pediatric ward. She came to the urgent care clinic at the Family Practice Center with symptoms of mild low back pain and right-sided lower abdominal pain which were associated with dysuria and frequency of urination during the previous 2 months. She had suffered an episode of low back pain 2 years earlier. Her urine showed a mildly positive leukocyte esterase test and a trace of protein, and she was given a course of trimethoprim.

Ten days later she returned reporting that the abdominal pain had become much worse, particularly when sitting and lying down, and it kept her awake at night. She complained of a feeling of fullness in the right lower quadrant of the abdomen. There were no changes in her bowel habit, and she had no fever, nausea, or anorexia. She was taking maximum doses of ibuprofen and acetaminophen for the pain. A repeat urinalysis was normal. She had previously had a hysterectomy and appendectomy, as well as polycystic ovaries, but the results of a pelvic examination were normal. Examination of the abdomen revealed normal bowel sounds and some tenderness in the right lower quadrant, close to the superior iliac spine. Because of her history of persistent back pain and a lack of explanation for her abdominal symptoms, x-rays of the lumbosacral spine and pelvis were ordered.

When she was seen again 2 days later, the abdominal pain had become much more severe. It was sharp, intermittent, not colicky, and traveled down into the groin and right anterior thigh. There was considerably less pain when she was standing. She had normal bowel sounds but was again acutely sensitive to palpation in the lower abdomen just above the anterior superior iliac crest. Assessment for acute abdominal pain included an electrolyte panel and complete blood count, which were normal except for a white blood count of 11,200. The lumbar and pelvic radiologic studies showed mild degeneration of the hip joints and some spurring of the inferior aspect of both sacroiliac joints.

With a working diagnosis of lower abdominal abscess, she was referred to the emergency department to be seen by the family medicine inpatient team. A computed tomography scan of the abdomen and pelvis was normal, showing only a small ovarian cyst on the left ovary. However, a repeat white blood count (several hours later) was 13,100. A surgical consultation was requested, but the surgeon found no evidence of an acute abdominal process, giving his opinion that this was a musculoskeletal problem.

At the suggestion of one of the family medicine faculty a more detailed examination of the sacroiliac joints was performed, and the resident found significant point tenderness over the right sacroiliac joint. Deep palpation of this joint area also produced pain radiating to the right inguinal region. It was felt that the acute abdominal problem might be caused by referred pain from the sacroiliac joint. The patient received an injection of 60 mg ketorolac tromethamine, which produced considerable relief, and she was sent home. However, there was no clear explanation for the 2 occasions of elevated white blood cell count.

At follow-up 10 days later the abdominal pain had subsided, but she was complaining of much more pain in the right lower back with referral down the front of her thighs. There was still tenderness over the right sacroiliac joint, and she was sent to a physical therapist for evaluation and treatment. During her first visit to the physical therapist, in addition to the low back symptoms she again reported increasing right lower abdominal pain that was worse when sitting, better when standing. Careful examination revealed an extremely tender 3 cm long, partly mobile, fibro-fatty nodule along the mid-region of the right iliac crest, approximately 4 inches lateral to the spinous process of the lumbar vertebra. Repeated firm, direct pressure on this nodule made the patient cry and reproduced the right lower abdominal symptoms.

Following injection with multiple puncture technique, lidocaine hydrochloride 3 cc and methyprednisolone acetate 40 mg, the patient experienced immediate pain relief with no more abdominal symptoms and no difficulty in sitting or lying down. Since that time (2 years ago), there has been no recurrence of these symptoms. Although the cause of the abdominal pain might have been a polycystic ovary, the workup did not support this conclusion and revealed no other obvious cause for the severe symptoms. Injecting a painful nodular swelling in the lower back that fitted the characteristics of previously described fibro-fatty nodules provided immediate relief of the pain, suggesting a possible association with the anterior abdominal symptoms.

Discussion

Do Back Mice Really Exist?

There is general agreement in a number of published case series from various rheumatologic and hospital populations that these nodules do exist, with an estimated prevalence of 15% in the general population.^5,7 These studies all report characteristic locations and clinical findings of a rubbery, well-defined, often mobile, round or oval swelling in the deep subcutaneous tissues. Though these can be painful, they never show evidence of infection and are frequently asymptomatic. The only other frequently found nodules with a similar anatomical location are lipomas (more superficial and soft to palpation) and sebaceous cysts (more superficial and usually circular).

Why Would Back Mice Masquerade as Other Conditions?

It is difficult to postulate a direct mechanical effect in which a low back nodule would produce pain at a distant location, so it is more likely that this is some form of referred pain. The authors of previous studies have reported that these nodules may mimic sciatic nerve root compression and lead to a diagnosis of vertebral disk prolapse.^6-8 The 2 cases we report appear to show a pattern different from that of the sciatic nerve. The first case is similar to data reported by Collee and colleagues⁹ in a study of hospital and primary care patients suffering from low back pain. They found that a substantial proportion of patients (45% and 25%, respectively) with low back pain also complained of greater trochanteric pain syndrome. There may be a specific referral pathway linking the 2 areas. It is more difficult to explain an association between a back mouse and the symptoms of abdominal pain in the second case. One possible mechanism could be a referral pattern, well reported in the literature, that comes from musculoskeletal structures (fascia, muscle, fibrous tissue, tendons) and follows sclerotomal distribution rather than the segmental dermatomes shown in most anatomical texts.^10-12 There is ample evidence that anterior abdominal pain can be referred from musculoskeletal elements in the low back region and can be quite severe.¹³ Referred pain from the fibrous capsule surrounding fibro-fatty nodules might explain the distant symptoms and signs in our 2 cases.

Where Do Back Mice Come From?

Pathologic studies show that these nodules consist of a fibrous capsule containing fat divided by fibrous septa and some fine blood vessels and nerve fibers, and they usually have a stalk connecting them to the tissues below the deep fascial layers.⁸ It has been suggested that these nodules and their stalks are formed by extrusion through the neurovascular foramina in the deep fascia as a result of mechanical stresses.

Why Would Back Mice Cause Pain?

The answer to this is not known. Nodules that have been examined after surgery have not shown evidence of inflammation as a cause of pain, though nerve fibers are found in the fibrous capsule. In our experience, the immediate relief of pain frequently produced by multiple needle puncture, compared with poor relief with a single puncture, suggests that the pain might be caused by raised intranodular pressure.⁶

Why Would Injections Relieve Pain Caused by Back Mice?

A recent long-term follow-up study of 35 patients showed that 89% had lasting relief. Generally, placebo effects from injections do not exceed 50% improvement.⁶ If lidocaine hydrochloride is used, its possible beneficial effects may come from washing out irritant chemicals (substance P) from the area, from local vasodilation that facilitates the removal of metabolites, or from the interruption of the neural feedback mechanism.¹³ However, the local anesthetic effect is too short to explain lasting relief, and a randomized controlled study of injection therapy of the iliac crest syndrome showed no difference in pain outcome between lidocaine hydrochloride and saline.¹⁴ This would tend to support the possibility that multiple puncture, rather than the injected material, is effective because it lessens the tension of the innervated fibrous capsule. Does Injection Treatment of the Back Mouse Really Work? There have been no randomized controlled trials and, until recently, no published long-term follow-up studies of treatment. It is not clear if multiple puncture of the nodule followed by deep massage alone is effective or whether the addition of local anesthetic and steroid improves outcome.

Conclusions

Until a rigorous study demonstrates the reliability and reproducibility of the clinical diagnosis of the back mouse and the effectiveness of treatment in a randomized controlled trial, our best advice for physicians, based purely on clinical and biased observation, is to consider the back mouse when atypical and unaccountable symptoms and signs are found in the lower abdomen, inguinal region, or legs.

Acknowledgements

We are grateful to Barry R. Howes, PT, and Robert E. Gwyther for guidance in the preparation of this report.