Laterally elevated wedged insoles in the treatment of medial knee osteoarthritis: a prospective randomized controlled study

Objective: To compare the clinical effects of laterally wedged insoles and neutrally wedged insoles (used as control) in patients with medial femoro-tibial knee osteoarthritis (OA).

Design: 6-month prospective randomized controlled study.

Patients: outpatients with painful medial femoro-tibial knee OA.

Outcome measures: patient's overall assessment of disease activity (5 grade scale), WOMAC index subscales and concomitant treatments.

Statistical analysis: Performed as an intention-to-treat analysis. Main criterion: improvement in the patient's assessment of activity (defined as a reduction of 1 grade or more at month 6 compared to baseline, and no intraarticular injection or lavage during the study). Secondary criteria for assessment: (a) improvement in the patient's assessment of activity at months 1 and 3 compared to baseline, (b) improvement in the WOMAC subscales at months 1, 3 and 6, compared to baseline (defined as an improvement of at least 30%, and no intraarticular injection or lavage during the study) and (c) concomitant therapies (analgesics and NSAIDs).

Results: The baseline characteristics of the 156 recruited patients (41 males, 115 females, mean age 64.8 years) were not different in the two treatment groups. At months 1, 3 and 6 the percentages of patients with improvement in assessment of disease activity, in WOMAC pain, joint stiffness, and physical functioning subscales were similar in the two groups. The number of days with NSAIDs intake during the previous 3 months was decreased at month 6 compared with baseline in the group furnished with laterally wedged insoles (14.1 days+/-28 vs 9.9 days+/-27, P=0.04, Wilcoxon paired test), while it remained unchanged in the other group (15.5 days+/-24 vs 15+/-28, P=0.56). Compliance and tolerance were satisfactory. Compliance was different between the two groups at month 6, with a greater frequency of patients who wore insoles permanently in the laterally wedged insole group than in the other group (87.8% vs 74.3%;P=0.032).

Conclusion: This study failed to demonstrate a relevant short-term symptomatic effect of laterally-wedged insoles in medial femoro-tibial OA. However, the decrease in NSAIDs consumption together with better compliance in the treated group are in favor of a beneficial effect of laterally-wedged insoles in medial femoro-tibial OA.