SAN DIEGO — Wedged shoe insoles may do little for medial knee osteoarthritic pain, according to a small, 18-week trial presented at the annual meeting of the American College of Rheumatology.
“A 5-degree lateral wedged insole was not efficacious in people with medial knee osteoarthritis in this particular trial,” said Kristin Baker, Ph.D., of the clinical epidemiology research and training unit at Boston University.
The randomized, double-blind, crossover trial, which enrolled 46 individuals with radiographically confirmed medial knee osteoarthritis, was designed to detect a 10% treatment effect on the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The wedged insole did not have this effect.
Given the patients' baseline WOMAC pain scores (a mean of 266 on the 0- to 500-point scale), a positive treatment effect would have been a decrease of 26–27 points. The study found that the wedge produced a mean 13-point benefit.
Use of a wedged insole did not result in the participants' being able to take less pain medication.
In a subgroup analysis, individuals with a body mass index (kg/m
The study began with a 2-week washout period, during which participants kept a pain diary. During the subsequent 6 weeks, subjects wore either a 5-degree lateral-wedge insole or a neutral insole. Then, for 4 more weeks, they did not wear any insole. For the final 6 weeks, participants crossed over and wore the other type of insole.
Patients were expected to wear the insoles for at least 8 hours per day, and their compliance rate was high, Dr. Baker said.