Mechanical and constitutional risk factors for symptomatic knee osteoarthritis: differences between medial tibiofemoral and patellofemoral disease.

OBJECTIVE: The generation of effective preventive strategies against knee osteoarthritis (OA) requires precise understanding of the individual risk factors for the condition. To identify these risk factors, we performed a population based case-control study of the disorder. METHODS: We compared 109 men and women with symptomatic, radiographically verified OA in the tibiofemoral (TFJ) and/or patellofemoral (PFJ) compartments of the knee joint with 218 community controls matched for age and sex. Information on risk factors was obtained by a structured interview and examination. RESULTS: Independent risk factors for knee OA included obesity (odds ratio [OR] 3.3; 95% confidence intervals [95% CI] 1.6-6.9), previous knee injury (OR 3.4; 95% CI 1.7-6.7), meniscectomy (OR 4.0; 95% CI 1.0-16.4), family history (OR 2.7; 95% CI 1.3-5.5) and Heberden's nodes (OR 2.0; 95% CI 1.1-3.6). Obesity and meniscectomy were stronger risk factors for medial TFJ disease, while Heberden's nodes and family history were more closely associated with PFJ involvement. CONCLUSION: Although based on small numbers, our results suggest that the relative contribution of mechanical and constitutional factors in the pathogenesis of OA in different compartments of the knee joint might vary. They also confirm the importance of significant knee injury and meniscectomy as risk factors for medial TFJ disease in the general population.