Major Finding: Knee osteoarthritis patients who placed wedge insoles in their shoes daily for 1 year had no benefit in pain or function, compared with control patients. These and other data appear to rule out the efficacy of wedge insoles for osteoarthritis.
Data Source: Randomized, controlled trial of 179 osteoarthritis patients.
Disclosures: 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.
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 finding means that knee osteoarthritis (OA) treatment recommendations from the European League Against Rheumatism (EULAR) and from the Osteoarthritis Research Society International (OARSI) need revision, Kim Bennell, Ph.D., said. 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.
Based on the consistent results from the four studies, “we can say [wedges] are not effective,” Dr. Bennell, professor of physiotherapy and director of the center for health, exercise, and sports medicine at the University of Melbourne, said at the congress, which was organized by OARSI.
Even though three previous studies showed wedge ineffectiveness, Dr. Bennell thought her study might show something different. “There are good biomechanical data in the lab showing that insoles reduce load” on the knee.
In the Melbourne study reported here, the researchers used full-length wedges, which Dr. Bennell thought would work better than heel insoles. The study also used MRI to assess structural outcomes, whereas prior studies used less-sensitive x-rays, she said in an interview.
The 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/m
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 wedges 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.