Objective: To identify factors associated with change in femoral cartilage volume over 2 years in a cohort largely without knee radiographic osteoarthritis.
Methods: A total of 252 subjects (mean 45 years, range 28-60) were used for this study. T1-weighted fat saturation magnetic resonance imaging was performed at baseline and approximately 2 years later. Knee femoral condyle cartilage volume, femoral cartilage defect (0-4 scale) and tibial bone size were determined.
Results: The total femoral cartilage volume loss was 6.3% for the 2.3-year period. Factors associated with this annual change were female gender (females vs males: -1.69%, P<0.01), age (over vs under 40 years: -0.96%, P=0.01), smoking (beta: -0.04% per pack-years, P<0.01), as well as lower limb muscle strength (r: +0.32, P<0.01) and its change (beta: +0.34% per quartile, P<0.05). Structural factors associated with change included baseline femoral cartilage volume (beta: -0.36% per ml, P<0.01), femoral cartilage defects (beta: +1.07% per grade, P<0.01), tibial bone area (beta: +0.13% per cm(2), P<0.05), lateral osteophytes (beta: -1.91% per grade, P<0.01) and change in femoral cartilage defects (beta: -0.8% per grade, P<0.001).
Conclusions: This study provides evidence confirming that significant risk factors are associated with femoral cartilage loss and these include gender (female), age, smoking, and severity of lower limb muscle weakness. It also supports the hypothesis that femoral cartilage swelling reflected by an increased baseline cartilage volume could be a predictor of disease progression. Our findings also provide interesting clues to implement preventive measures that can possibly prevent or reduce knee cartilage loss.