Intra-Articular Mineralization on Knee CT and Risk of Cartilage Damage: The Multicenter Osteoarthritis Study.

OBJECTIVES: Intra-articular (IA) mineralization may contribute to OA structural progression. We studied the association of IA mineralization on knee CT with cartilage damage worsening on knee MRI, with a focus on location- and tissue-specific effects.

METHODS: Participants from the Multicenter Osteoarthritis study with knee CTs and MRIs were included. Presence of IA mineralization on CT was defined as a Boston University Calcium Knee Score (BUCKS) >0 anywhere in the knee. Cartilage worsening on MRI was defined as any increase in MRI OA Knee Score (MOAKS) including incident damage. We evaluated the association of whole-knee, compartment-specific (i.e., medial or lateral), and subregion-specific (i.e., location-matched) IA mineralization at baseline with cartilage worsening at 2-year follow-up in the corresponding locations using binomial regression with generalized estimating equations, adjusting for age, sex, and body mass index (BMI).

RESULTS: We included 1673 participants (mean age 60 years, 56% female, mean BMI 29 kg/m2 ). 9.0% had any IA mineralization in the knee and 47.4% had any cartilage worsening on follow-up. Mineralization of any tissue in the knee, regardless of location, was not associated with MRI cartilage worsening. However, cartilage mineralization was associated with 1.39 (95% CI 1.04, 1.88) times higher risk of cartilage worsening in the same compartment with similar results in subregion-specific analysis.

CONCLUSIONS: CT-detected IA mineralization in the cartilage was associated with higher risk of MRI cartilage worsening in the same compartment and subregion over two years. These findings suggest potential localized, tissue-specific effects of IA mineralization on cartilage pathology in knee OA.