Association of Periarticular Subchondral Bone Mineral Density With the Presence and Progression of Knee Pain: Data From the Osteoarthritis Initiative

Objective To explore the association between periarticular subchondral bone mineral density (sBMD) and the presence and progression of osteoarthritis (OA) knee pain. Methods Participants were recruited from the Osteoarthritis Initiative (OAI). Tibial sBMD at medial and lateral compartments was measured by dual-energy x-ray absorptiometry at 30 or 36 months (baseline) and reassessed at 48 months. Knee pain was assessed using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain subscale (range 0-20, with a higher score indicating greater pain) through month 108. Baseline knee pain was categorized as low/no or high (pain score < 5 vs ≥ 5). Pain progression was defined as an increase in WOMAC pain score of ≥ 2 in at least 3 of the 6 follow-up visits. Logistic regression with generalized estimating equations was used to assess associations between sBMD (per SD increase) and knee pain, accounting for within-participant correlation between knees. Results Of 594 participants (mean age 64.1 years; 50.5% male; 1137 knees), 31.6% of knees exhibited higher pain at baseline, and 37.4% demonstrated pain progression during follow-up. Higher medial sBMD and medial-to-lateral sBMD ratio were associated with the progression of knee pain (medial sBMD: odds ratio [OR] 1.50; 95% CI 1.25-1.81; P < 0.001; medial-to-lateral ratio: OR 1.29; 95% CI 1.11-1.49; P = 0.001). Medial-to-lateral sBMD ratio was also associated with the presence of knee pain (OR 1.21; 95% CI 1.05-1.40; P = 0.01). Conclusion Higher medial-to-lateral sBMD ratio was associated with both the presence and progression of knee pain, suggesting that relative subchondral bone distribution may better capture biomechanical loading imbalance related to symptomatic OA than absolute sBMD alone.