BRUSSELS — Lateral wedge insoles placed in the shoes of patients with knee osteoarthritis gave no benefit and produced foot discomfort in a controlled study with 179 participants who completed 1 year of treatment. The withdrawal of wedge insoles as a recommended treatment option seems likely, as the new findings make the fourth – and largest – study to show no benefit in either pain or function and the first to show an absence of cartilage benefit by MRI examination, said researcher Kim Bennell, PhD, at the World Congress on Osteoarthritis. Based on the consistent results from four studies, “we can say [wedges] are not effective,” said Dr. Bennell, professor of physiotherapy and director of the center for health, exercise, and sports medicine at the University of Melbourne. Dr. Bennell said she thought her study might show something different. “There are good biomechanical data in the lab showing that insoles reduce load” on the knee, she pointed out. Also, the prior three studiesahad various flaws. The longest swhich ran 2 years, used patients with a variety of osteoarthritis types. Dr. Bennell's study used only patients with medial knee OA, the specific form most likely to respond to the knee unloading. Another study lasted only 6 weeks. The new study also used full-length wedges, which Dr. Bennell thought would work better than heel insoles. Plus, the new study used MRI to assess structural outcomes, whereas prior studies used less-sensitive x-rays, she said in an interview. The most recent recommendations for managing knee OA from the Osteoarthritis Research Society International (OARSI), published in 2008, say, “In patients with knee osteoarthritis [lateral wedge] insoles can reduce pain and improve ambulation” (Osteoarthritis Cartilage 2008;16:137-62). The new study recruited patients aged 50 years and older from the community who had knee pain on walking over the medial region with medial osteophytes and joint narrowing, a mechanical axis of 182 degrees or less, and a Kellgren-Lawrence (KL) grade of 2 or 3. The 200 patients who entered the study averaged 64 years old, about 60% were women, their average symptom duration was 7 years, their average body mass index was about 29 kg/m2, and they split evenly between having KL grade 2 or 3 disease. Every day, the randomized patients placed in their shoes either a wedge insole with a 5-degree pitch, or a flat, fully compressible control insole. Treatment ran for 1 year, with the insoles replaced quarterly. Patients in the wedge group reported wearing their insoles for an average of 7 hours daily, whereas the controls used theirs for an average of 9 hours daily. The study's primary outcomes (assessments of pain and cartilage structure) showed no significant differences between the 89 patients who completed 1 year in the wedge group and the 90 control patients who finished 1 year. The two groups also had no significant differences in measures of function. The main difference between the treatment groups was that 47% of wedge users and 23% of controls self-reported problems with the insoles. Reports of foot pain came from 36% of wedge users and 16% of controls. The discomfort was rated as severe by 10% of wedge users and 1% of controls. The difference in average time of insole use most likely had no effect on outcomes, Dr. Bennell said at the congress, which was organized by OARSI. Her group ran a model that extrapolated the impact of continuous wedge insole use and found that the results stayed the same. Dr. Bennell said that she has no disclosures for this study. She said that she had received research support for other studies from Essex, an Australian running-shoe manufacturer.
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Dec 31, 2013
Byung Sung Kim + 6
