To determine the prevalence of pre-radiographic osteoarthritis (ROA) and ROA of the knee in a symptomatic population-based cohort, and to evaluate the clinical correlates of pre-ROA and ROA.
Subjects ages 40-79 years with knee pain were recruited as a random population sample and classified using magnetic resonance cartilage (MRC) scores (range 0-4) and Kellgren/Lawrence (K/L) scale grades (range 0-4) as no OA (MRC score<2, K/L grade<2), pre-ROA (MRC score ≥2, K/L grade<2), and ROA (MRC score≥2, K/L grade≥2). Logistic regression was used to evaluate the association of clinical variables with cartilage defects, comparing subjects with any cartilage defects (pre-ROA/ROA) with those without, and to determine associations with individual OA subgroups.
Of 255 symptomatic subjects, no OA, pre-ROA, and ROA were seen in 13%, 49%, and 38%, respectively. The prevalence of pre-ROA/ROA compared with no OA was associated with age (odds ratio [OR] 2.89, 95% confidence interval [95% CI] 1.59-5.26), sports activity (OR 1.35, 95% CI 1.07-1.70), abnormal gait (OR 10.86, 95% CI 1.46-1,388.4), effusion (OR 16.58, 95% CI 2.22-2,120.5), and flexion contracture (OR 2.37, 95% CI 1.50-3.73). The prevalence of ROA versus no OA was significantly associated with age, body mass index, pain frequency, pain duration, severe knee injury, sports activity, gait, effusion, bony swelling, crepitus, flexion contracture, and flexion. The prevalence of pre-ROA versus no OA was increased with age, sports activity, effusion, and flexion contracture, and reduced with valgus malalignment.
Cartilage defects were highly prevalent in this symptomatic population-based cohort, with 49% of subjects having pre-ROA and 38% having ROA. Prevalent cartilage defects were significantly associated with age, sports activity, abnormal gait, effusion, and flexion contracture.