Hazard of Incident and Progressive Knee and Hip Radiographic Osteoarthritis and Chronic Joint Symptoms in Individuals with and without Limb Length Inequality

Objective. To examine the hazard of incident and progressive radiographic osteoarthritis (rOA) and chronic joint symptoms at the hip and knee by limb length inequality (LLI) in a large, community-based sample. Methods. A longitudinal cohort completed baseline (1991-97) clinical evaluation and identical followup assessment (1999-2003) (median followup time 5.9 yrs, range 3.0-13.1 yrs). LLI was defined at baseline as a measured difference between limbs >= 2 cm. The study groups with LLI data comprised 1583 participants with paired (baseline and followup) knee radiographs and 1453 participants with paired hip radiographs. Multivariable Cox regression models were used to examine the hazard of incident and progressive knee and hip rOA and chronic joint symptoms, with adjustment for demographic and clinical factors. Results. The hazard of developing incident knee or hip rOA was 20%-30% higher and of developing progressive knee or hip rOA was 35%-83% higher among participants with LLI, but results were only statistically significant for progressive knee rOA (adjusted hazard ratio = 1.83, 95% CI 1.10-3.05). The hazards of progressive chronic knee symptoms and incident and progressive chronic hip symptoms were 13%-59% higher among participants with LLI, but were not statistically significant. Conclusion. LLI was associated with progressive knee rOA and was nonsignificantly associated with incident knee or hip rOA and progressive hip rOA, progressive chronic knee symptoms, and incident and progressive chronic hip symptoms. Longer studies may strengthen these associations and help determine whether LLI is a risk factor or marker of these outcomes. (First Release July 15 2010; J Rheumatol 2010;37:2133-40; doi:10.3899/jrheum.091410)