Strapped Insole Improves Knee Osteoarthritis Pain

CHICAGO — Use of a laterally wedged insole with strapping of the subtalar joint can improve pain and correct abnormal biomechanics due to varus alignment in medial compartment osteoarthritis of the knee, Yoshitaka Toda, M.D., said at the 2004 World Congress on Osteoarthritis.

The idea is that an insole can correct varus alignment by creating valgus correction, resulting in a reduction of medial knee joint surface loading, said Dr. Toda, who has an orthopedic rheumatology practice in Osaka, Japan.

Previous attempts to achieve such a correction with a shoe insert haven't been successful, he said, perhaps because of movement of the talus.

Instead, an insole that's fixed in place with subtalar strapping prevents the talus from moving and creates tension to correct the femorotibial angle, he explained.

In a study designed to assess the optimal daily usage of the device, which was developed and patented by Dr. Toda, 81 women with knee osteoarthritis were randomly assigned to wear the insole for less than 5 hours a day (short group), between 5 hours and 10 hours (medium group), for more than 10 hours (long group), or to wear a placebo subtalar strapping band without the wedge insert. Both of the groups were treated for 2 weeks.

All patients also were treated with oral NSAIDs twice a day as adjunctive therapy. There were no differences between groups in terms of age, disease duration, body mass, height, or femorotibial angle.

All patients with varus knee osteoarthritis who wore the orthotic device daily had a significantly greater valgus correction of the femorotibial angle on standing radiographs than did patients in the placebo group.

The average time spent actually wearing the device was 3.5 hours in the short group, 6.9 hours in the medium group, and 14.2 hours in the long group, according to patient diaries.

The optimal time for wearing the device appears to be between 5 and 10 hours a day, Dr. Toda said at the congress, which was sponsored by the Osteoarthritis Research Society International.

In the short, medium, and long groups, the femorotibial angle was reduced by an average of 2.4 degrees, 2.2 degrees, and 2.5 degrees, respectively. The femorotibial angle in the placebo group increased by 1.8 degrees.

Pain remission scores on the Lequesne Functional Severity Index at 2 weeks were significantly improved from baseline in the medium group (−5.9) compared with the placebo (−1.9) and long groups (−2.3). The short group score was −4.6.

Maximum improvement on the severity index occurred among patients who wore the device for 8 hours per day, Dr. Toda said.

“A possible reason for the reduced improvement in the long group might be that the continuing reduction in the femorotibial angle resulted in fatigue of surrounding muscles, which had been compensating for the deformity,” Dr. Toda said.

The poor results in the placebo group suggest that the improvements seen in patients wearing the device for 5–10 hours were due to changes in the femorotibial angle and not to the effects of NSAIDs.

The insole offers a possible alternative for patients with knee osteoarthritis who are hesitant to undergo pharmacologic or surgical treatment, Dr. Toda added. Follow-up studies are planned to determine if the device alters or delays OA progression.

Patients would be wise to consult their physicians before using devices such as Dr. Toda's, said Neil Segal, M.D., of the department of orthopedics and rehabilitation at the University of Iowa, Iowa City. “We're still studying the biomechanics of what leads to OA,” he said.

This device may help patients with medial compartment OA who have varus forces on that compartment. But it won't help patients with lateral compartment OA, and it might even make them worse.

The femorotibial angle, formed by the axes of the femur and tibia, before treatment with the insole. Courtesy Dr. Yoshitaka Toda

After treatment with the strapped insole, the femorotibial angle was reduced by about 5 degrees. Courtesy Dr. Yoshitaka Toda

The insole is secured with straps around the subtalar joint, preventing the talus from moving. James Reinaker

CHICAGO — Use of a laterally wedged insole with strapping of the subtalar joint can improve pain and correct abnormal biomechanics due to varus alignment in medial compartment osteoarthritis of the knee, Yoshitaka Toda, M.D., said at the 2004 World Congress on Osteoarthritis.

The idea is that an insole can correct varus alignment by creating valgus correction, resulting in a reduction of medial knee joint surface loading, said Dr. Toda, who has an orthopedic rheumatology practice in Osaka, Japan.

Previous attempts to achieve such a correction with a shoe insert haven't been successful, he said, perhaps because of movement of the talus.

Instead, an insole that's fixed in place with subtalar strapping prevents the talus from moving and creates tension to correct the femorotibial angle, he explained.

In a study designed to assess the optimal daily usage of the device, which was developed and patented by Dr. Toda, 81 women with knee osteoarthritis were randomly assigned to wear the insole for less than 5 hours a day (short group), between 5 hours and 10 hours (medium group), for more than 10 hours (long group), or to wear a placebo subtalar strapping band without the wedge insert. Both of the groups were treated for 2 weeks.

All patients also were treated with oral NSAIDs twice a day as adjunctive therapy. There were no differences between groups in terms of age, disease duration, body mass, height, or femorotibial angle.

All patients with varus knee osteoarthritis who wore the orthotic device daily had a significantly greater valgus correction of the femorotibial angle on standing radiographs than did patients in the placebo group.

The average time spent actually wearing the device was 3.5 hours in the short group, 6.9 hours in the medium group, and 14.2 hours in the long group, according to patient diaries.

The optimal time for wearing the device appears to be between 5 and 10 hours a day, Dr. Toda said at the congress, which was sponsored by the Osteoarthritis Research Society International.

In the short, medium, and long groups, the femorotibial angle was reduced by an average of 2.4 degrees, 2.2 degrees, and 2.5 degrees, respectively. The femorotibial angle in the placebo group increased by 1.8 degrees.

Pain remission scores on the Lequesne Functional Severity Index at 2 weeks were significantly improved from baseline in the medium group (−5.9) compared with the placebo (−1.9) and long groups (−2.3). The short group score was −4.6.

Maximum improvement on the severity index occurred among patients who wore the device for 8 hours per day, Dr. Toda said.

“A possible reason for the reduced improvement in the long group might be that the continuing reduction in the femorotibial angle resulted in fatigue of surrounding muscles, which had been compensating for the deformity,” Dr. Toda said.

The poor results in the placebo group suggest that the improvements seen in patients wearing the device for 5–10 hours were due to changes in the femorotibial angle and not to the effects of NSAIDs.

The insole offers a possible alternative for patients with knee osteoarthritis who are hesitant to undergo pharmacologic or surgical treatment, Dr. Toda added. Follow-up studies are planned to determine if the device alters or delays OA progression.

Patients would be wise to consult their physicians before using devices such as Dr. Toda's, said Neil Segal, M.D., of the department of orthopedics and rehabilitation at the University of Iowa, Iowa City. “We're still studying the biomechanics of what leads to OA,” he said.

This device may help patients with medial compartment OA who have varus forces on that compartment. But it won't help patients with lateral compartment OA, and it might even make them worse.

The femorotibial angle, formed by the axes of the femur and tibia, before treatment with the insole. Courtesy Dr. Yoshitaka Toda

After treatment with the strapped insole, the femorotibial angle was reduced by about 5 degrees. Courtesy Dr. Yoshitaka Toda

The insole is secured with straps around the subtalar joint, preventing the talus from moving. James Reinaker

CHICAGO — Use of a laterally wedged insole with strapping of the subtalar joint can improve pain and correct abnormal biomechanics due to varus alignment in medial compartment osteoarthritis of the knee, Yoshitaka Toda, M.D., said at the 2004 World Congress on Osteoarthritis.

The idea is that an insole can correct varus alignment by creating valgus correction, resulting in a reduction of medial knee joint surface loading, said Dr. Toda, who has an orthopedic rheumatology practice in Osaka, Japan.

Previous attempts to achieve such a correction with a shoe insert haven't been successful, he said, perhaps because of movement of the talus.

Instead, an insole that's fixed in place with subtalar strapping prevents the talus from moving and creates tension to correct the femorotibial angle, he explained.

In a study designed to assess the optimal daily usage of the device, which was developed and patented by Dr. Toda, 81 women with knee osteoarthritis were randomly assigned to wear the insole for less than 5 hours a day (short group), between 5 hours and 10 hours (medium group), for more than 10 hours (long group), or to wear a placebo subtalar strapping band without the wedge insert. Both of the groups were treated for 2 weeks.

All patients also were treated with oral NSAIDs twice a day as adjunctive therapy. There were no differences between groups in terms of age, disease duration, body mass, height, or femorotibial angle.

All patients with varus knee osteoarthritis who wore the orthotic device daily had a significantly greater valgus correction of the femorotibial angle on standing radiographs than did patients in the placebo group.

The average time spent actually wearing the device was 3.5 hours in the short group, 6.9 hours in the medium group, and 14.2 hours in the long group, according to patient diaries.

The optimal time for wearing the device appears to be between 5 and 10 hours a day, Dr. Toda said at the congress, which was sponsored by the Osteoarthritis Research Society International.

In the short, medium, and long groups, the femorotibial angle was reduced by an average of 2.4 degrees, 2.2 degrees, and 2.5 degrees, respectively. The femorotibial angle in the placebo group increased by 1.8 degrees.

Pain remission scores on the Lequesne Functional Severity Index at 2 weeks were significantly improved from baseline in the medium group (−5.9) compared with the placebo (−1.9) and long groups (−2.3). The short group score was −4.6.

Maximum improvement on the severity index occurred among patients who wore the device for 8 hours per day, Dr. Toda said.

“A possible reason for the reduced improvement in the long group might be that the continuing reduction in the femorotibial angle resulted in fatigue of surrounding muscles, which had been compensating for the deformity,” Dr. Toda said.

The poor results in the placebo group suggest that the improvements seen in patients wearing the device for 5–10 hours were due to changes in the femorotibial angle and not to the effects of NSAIDs.

The insole offers a possible alternative for patients with knee osteoarthritis who are hesitant to undergo pharmacologic or surgical treatment, Dr. Toda added. Follow-up studies are planned to determine if the device alters or delays OA progression.

Patients would be wise to consult their physicians before using devices such as Dr. Toda's, said Neil Segal, M.D., of the department of orthopedics and rehabilitation at the University of Iowa, Iowa City. “We're still studying the biomechanics of what leads to OA,” he said.

This device may help patients with medial compartment OA who have varus forces on that compartment. But it won't help patients with lateral compartment OA, and it might even make them worse.

The femorotibial angle, formed by the axes of the femur and tibia, before treatment with the insole. Courtesy Dr. Yoshitaka Toda

After treatment with the strapped insole, the femorotibial angle was reduced by about 5 degrees. Courtesy Dr. Yoshitaka Toda

The insole is secured with straps around the subtalar joint, preventing the talus from moving. James Reinaker