A randomized crossover trial of a wedged insole for treatment of knee osteoarthritis
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Kristin Baker1, Joyce Goggins, Hui Xie
1Veterans Affairs Boston Health Care System, Boston University Medical School, Massachusetts 02118, USA. krbaker@bu.edu
Objective:
In uncontrolled studies, a lateral-wedge insole has reduced knee pain in patients with medial knee osteoarthritis (OA). The aim of this study was to test the efficacy of this simple, low-cost intervention for pain in patients with medial knee OA.
Methods:
We conducted a double-blind, randomized, crossover trial designed to detect a small effect of treatment. Participants were at least 50 years of age and had medial joint space narrowing on posteroanterior semiflexed radiographs and scores indicating moderate pain for 2 of the 5 items on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale. Participants were randomized to receive a 5 degrees lateral-wedge insole or a neutral insole for 6 weeks. Following a 4-week washout period, participants crossed over to the other treatment for 6 weeks. Knee pain, the primary outcome, was assessed by the WOMAC pain scale (visual analog scale version). Secondary outcomes included the WOMAC disability subscale, overall knee pain, 50-feet walk time, chair-stand time, and use of medications for knee pain.
Results:
Ninety patients were randomized. The mean difference in pain between the 2 treatments was 13.8 points on the WOMAC pain scale (95% confidence interval -3.9, 31.4 [P=0.13]). We observed similar small effects for the secondary outcomes.
Conclusion:
The effect of treatment with a lateral-wedge insole for knee OA was neither statistically significant nor clinically important.
