132 - IS INTRA-ARTICULAR CALCIFICATION ASSOCIATED WITH UNPREDICTABLE PAIN IN KNEE OSTEOARTHRITIS?: DATA FROM THE MULTICENTER OSTEOARTHRITIS STUDY

Jean Liew; Mohamed Jarraya; Sarah Tilley; Gillian Hawker; Ali Guermazi; John A. Lynch; Michael C. Nevitt; James Torner; Beth Lewis; Tuhina Neogi

doi:10.1016/j.joca.2026.01.144

Purpose (the aim of the study): Chondrocalcinosis in the setting of CPPD disease can be associated with acute flares of pain and inflammation (i.e., acute CPP arthritis, previously known as “pseudogout”). Chondrocalcinosis is common in knee osteoarthritis (OA), but its clinical implications have been unclear. Using computed tomography (CT), which is more sensitive than plain radiographs for chondrocalcinosis, we previously demonstrated that IA calcification was associated with development of more frequent and severe knee pain longitudinally. However, whether IA calcification (possibly through low grade inflammation) can contribute to pain fluctuations or bouts of unpredictable pain is not known. Methods: We used data from the Multicenter Osteoarthritis (MOST) Study, a NIH-funded longitudinal cohort of people with or at risk of knee OA. The 12th-year visit, the first study visit at which CTs were obtained, was the baseline for this analysis. All participants had knee radiographs and bilateral knee CTs at baseline, and were assessed for pain outcomes with the ICOAP questionnaire at baseline and 2-year follow-up. A musculoskeletal radiologist scored multiplanar CT images (axial native images with coronal and sagittal reformats) using the Boston University Calcium Knee Score (BUCKS). Calcification in each of WORMS-defined subregions of cartilage and menisci was scored on a 0-3 scale. The outcome of interest was unpredictable knee pain, categorized from ICOAP as follows: i) intermittent pain with unpredictable knee pain episodes (“unpredictable pain”); ii) “other pain patterns” defined as intermittent pain (without unpredictable pain episodes) or constant pain; iii) no pain. We examined presence of any IA calcification to the presence of prevalent unpredictable knee pain cross-sectionally, and the risk of developing incident unpredictable knee pain longitudinally among those without unpredictable knee pain at baseline. We carried out knee-specific analyses using multinomial logistic regression with GEE and adjusted for age, sex, BMI, race, and KL grade; we repeated analyses without adjustment for KL grade because prior work has demonstrated that IA calcification can contribute to and precede cartilage worsening and thus OA may be an intermediate in the causal pathway. Results: Cross-sectionally we included 2019 people (4165 knees) (mean age 61 years, mean BMI 29, 57% female). Overall, 10.1% of knees had IA calcification at baseline, 16.8% had unpredictable pain, 24.3% experienced other pain patterns. There was no statistically significant cross-sectional association between IA calcification and prevalent unpredictable pain (OR 0.89, 95% CI 0.63, 1.26). Longitudinally we included 1668 people (3024 knees) who were free of unpredictable pain at baseline, and 11.1% developed incident unpredictable pain. The longitudinal association between IA calcification and incident unpredictable pain was also not statistically significant (OR 0.82, 95% CI 0.53, 1.27). However, there was a longitudinal association between IA calcification and “other pain patterns” (OR 1.38, 95% CI 0.99-1.92 with adjustment for KL grade; OR 1.57, 95% CI 1.14-2.16 without adjustment for KL grade). Conclusions: Although we hypothesized that calcium crystal deposition within the joint may be implicated in episodes of unpredictable pain flares, IA calcification was not associated with presence or risk of developing unpredictable knee pain over two years. However, IA calcification was associated with other intermittent or constant pain patterns over 2 years.

132 - IS INTRA-ARTICULAR CALCIFICATION ASSOCIATED WITH UNPREDICTABLE PAIN IN KNEE OSTEOARTHRITIS?: DATA FROM THE MULTICENTER OSTEOARTHRITIS STUDY

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