The Effect of Flat Flexible Versus Stable Supportive Shoes on Knee Osteoarthritis Symptoms
Kade L. Paterson, Kim L. Bennell, Penny K. Campbell, Ben R. Metcalf, Tim V. Wrigley, Jessica Kasza, Rana S. Hinman
Abstract
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.