A new approach to prevention of knee osteoarthritis: reducing medial load in the contralateral knee

Abstract

Background. Few if any prevention strategies are available for knee osteoarthritis (OA). In those with symptomatic medial OA, the contralateral knee may be at high risk of disease and a reduction in medial loading in that knee might prevent disease or its progression there. Lateral wedge insoles reduce loading across an affected medial knee but their effect on the contralateral knee is unknown.
Methods: To determine the proportion of persons with medial knee OA who had concurrent medial contralateral OA or developed contralateral medial OA later, we examined knee radiographs from the longitudinal Framingham Osteoarthritis Study. Then, to examine an approach to reducing medial load in the contralateral knee, 51 people from a separate study with painful medial tibiofemoral OA underwent gait analysis wearing bilateral controlled shoes with i) no insoles ii) two types of lateral wedge insoles laterally posted by 5 degrees. Primary outcome was the external knee adduction moment (EKAM) in the contralateral knee. Non-parametric confidence intervals were constructed around the median differences in percentage change in the affected and contralateral sides.
Results: Of Framingham subjects with medial radiograph knee OA, 137/152 (90%) either had concurrent contralateral medial OA or developed it within 10 years. 43/67 (64%) of those with medial symptomatic knee OA had or developed the same disease state in the contralateral knee. Compared to a control shoe, medial loading was reduced substantially on both the affected (median percentage EKAM change =-4.84%; 95% CI -11.33% to -0.65%) and contralateral sides (median EKAM percentage change -9.34% (95% CI -10.57% to -6.45%).
Conclusions: In persons with medial OA, the contralateral knee is also at high risk of medial OA. Bilateral reduction in medial loading in knees by use of strategies such as lateral wedge insoles might not only reduce medial load in affected knees but prevent knee OA or its progression on the contralateral side.