A New Approach to Prevention of Knee Osteoarthritis: Reducing Medial Load in the Contralateral Knee

Objective. Few if any prevention strategies are available for knee osteoarthritis (OA). In those withsymptomatic medial OA, the contralateral knee may be at high risk of disease, and a reduction inmedial loading in that knee might prevent disease or its progression there. Our aim was to determinehow often persons with medial OA on 1 side had either concurrent or later medial OA on the contralateral side, and whether an intervention known to reduce medial loading in affected knees withmedial OA might reduce medial loading in the contralateral knee. Lateral wedge insoles reduceloading 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 medialcontralateral OA or developed contralateral medial OA later, we examined knee radiographs fromthe longitudinal Framingham Osteoarthritis Study. Then, to examine an approach to reducing medialload in the contralateral knee, 51 people from a separate study with painful medial tibiofemoral OAunderwent gait analysis wearing bilateral controlled shoes with no insoles, and then with 2 types ofwedge insoles laterally posted by 5°. Primary outcome was the external knee adduction moment(EKAM) in the contralateral knee. Nonparametric CI 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 hadconcurrent contralateral medial OA or developed it within 10 years. Of those with medial symptomatic knee OA, 43/67 (64%) 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 (medianpercentage EKAM change –4.84%; 95% CI –11.33% to –0.65%) and contralateral sides (medianpercentage EKAM change –9.34%; 95% CI –10.57% to –6.45%). Conclusion. 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 mightnot only reduce medial load in affected knees but prevent knee OA or its progression on the contralateral side. (First Release Jan 15 2013; J Rheumatol 2013;40:309–15; doi:10.3899/jrheum.120589