The Effect of Flat Flexible Versus Stable Supportive Shoes on Knee Osteoarthritis Symptoms

Background: Experts recommend that persons with knee osteoarthritis wear stable supportive shoes; however, evidence suggests that flat flexible shoes may be more beneficial. Objective: To compare flat flexible with stable supportive shoes for knee osteoarthritis symptoms. Design: Participant- and assessor-blinded randomized trial. (Prospectively registered with the Australian New Zealand Clinical Trials Registry [ACTRN12617001098325]) Setting: Community. Participants: 164 patients with moderate to severe symptomatic radiographic medial knee osteoarthritis. Intervention: Flat flexible (n = 82) or stable supportive shoes (n = 82), worn for at least 6 hours a day for 6 months. Measurements: Primary outcomes were changes in walking pain (measured by an 11-point numerical rating scale) and physical function (as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index subscale of 0 to 68 points) at 6 months. Secondary outcomes included additional pain and function measures, physical activity, and quality of life. Other measures included adverse events. Results: Of 164 participants recruited, 161 (98%) completed 6-month primary outcomes. No evidence was found that flat flexible shoes were superior to stable supportive shoes in primary outcomes. Evidence did show a between-group difference in change in pain favoring stable supportive shoes (mean difference, 1.1 units [95% CI, 0.5 to 1.8 units]; P = 0.001) but not function (mean difference, 2.3 units [CI, −0.9 to 5.5 units]; P = 0.167). Improvements in knee-related quality of life and ipsilateral hip pain favored stable supportive shoes (mean difference, −5.3 units [CI, −10.0 to −0.5 units] and 0.7 units [CI, 0.0 to 1.4 units], respectively). Flat flexible shoes were not superior to stable supportive shoes for any secondary outcome. Fewer participants reported adverse events with stable supportive shoes (n = 12 [15%]) compared with flat flexible shoes (n = 26 [32%]) (risk difference, −0.17 [CI, −0.30 to −0.05]). Limitation: No “usual shoes” control group and a select patient subgroup, which may limit generalizability. Conclusion: Flat flexible shoes were not superior to stable supportive shoes. Contrary to our hypothesis, stable supportive shoes improved knee pain on walking more than flat flexible shoes. Primary Funding Source: National Health and Medical Research Council.