CT-derived proximal tibial bone density imbalance is associated with knee osteoarthritis

Compartmental imbalance in proximal tibial bone density may contribute to the structural progression of knee osteoarthritis (OA), yet remains underexplored using quantitative imaging. This study investigated the association between compartmental proximal tibial bone density, measured using CT-derived Hounsfield units (HU), and knee OA. This retrospective cross-sectional study analyzed 753 knees from patients who underwent lower-extremity CT, knee radiography, and orthoradiogram between 1995 and 2024 at a single tertiary center. The knees were categorized as OA (N = 238) or non-OA (N = 515) based on expert image review. The HU values were measured in three compartments: the medial plateau, lateral plateau, and central metaphysis. The absolute and relative HU differences between compartments (e.g., medial to lateral) were calculated. Associations with OA were assessed using multivariate logistic regression, adjusted for age and sex. The diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. In unadjusted comparison, OA-affected knees showed lower HU across proximal tibial subregions than non-OA knees. Higher medial HU values (OR per 100 HU: 1.49; p = 0.016) and greater medial-to-lateral HU differences (OR: 1.27; p = 0.089) were associated with OA. These relative differences were exaggerated with advancing age. Medial HU values showed moderate discriminative power (area under the curve AUC = 0.682), whereas medial-to-lateral differences had limited standalone performance (AUC = 0.553). Knees with OA were associated with asymmetric remodeling patterns of the proximal tibia, including higher medial subchondral density and lower metaphyseal bone density, suggestive of a compartmental imbalance. CT-derived HU values, along with absolute and relative compartmental differences, may serve as exploratory radiologic markers to support OA risk stratification.