Epidemiology and risk factors of patellofemoral osteoarthritis in adults: a population-based study in southern Thailand.

OBJECTIVE Study the epidemiology and factors associated with patellofemoral osteoarthritis. MATERIAL AND METHOD A population-based survey was undertaken in Songkhla, a province in the southern part of Thailand. Residents aged 40 years and older were sampled using primary care units as a primary sampling frame, stratified by age and sex. All participants were taken to a private clinic for an interview and radiographic examination, including anterior-posterior, lateral and skyline views of both knees. Types and severities of involvement in each compartment were graded by one musculoskeletal radiologist. RESULTS Of the eligible 694 subjects, 576 (81.4%) agreed to participate in the present study. The prevalence of radiographic patellofemoral osteoarthritis was 37.9%, of which 96% was bilateral involvement. Isolated patellofemoral osteoarthritis was the most common pattern in males (18.0%), while the combined pattern (involvement of both tibiofemoral and patellofemoral compartments) was the most common pattern in females (31.2%). Elderly (OR = 8.8, 95% CI: 5.1-15.3) and obese (OR = 7.9, 95% CI: 3.3-15.3) were independent risk factors predicting patellofemoral osteoarthritis. CONCLUSION There was a high prevalence of patellofemoral osteoarthritis among Thais over 40 years of age, associated with age and obesity.