The association of CT-detected intra-articular calcification with MRI-detected effusion-synovitis and Hoffa-synovitis in knee OA: The Multicenter Osteoarthritis study.

Abstract

Background: CT-detected intra-articular (IA) calcification from calcium crystal deposition is associated with worsening cartilage damage and knee pain in osteoarthritis (OA); whether there is associated joint inflammation is unclear. We studied the relation of CT-detected IA calcification to imaging evidence of inflammation (i.e., effusion-synovitis and/or Hoffa-synovitis) on knee MRI in middle-aged and older adults, focusing on tissue-specific relationships.

Methods: Participants from the Multicenter Osteoarthritis study with knee CTs and MRIs were included. Presence of IA calcification on CT was defined as Boston University Calcium Knee Score >0 in hyaline cartilage, meniscus, and capsule anywhere in the knee. Effusion-synovitis and Hoffa-synovitis were scored on MRI using MOAKS at baseline and two years later. We evaluated the relation of IA calcification (overall and in specific tissues) to presence of effusion-synovitis and/or Hoffa-synovitis longitudinally, using Poisson regression with generalized estimating equations, adjusting for age, sex, race, and body mass index.

Results: We included 1669 participants with available knee CT and MRI (mean age 60.6±9 years, 56% female, mean BMI 28.5±5 kg/m²; 21.6% knees with radiographic OA). Overall, at baseline, 9.2% had any IA calcification, 30.0% had effusion-synovitis, 37.0% Hoffa-synovitis, and 50% either effusion-synovitis and/or Hoffa-synovitis. The presence of any IA calcification was associated with 30% higher risk of effusion-synovitis and/or Hoffa-synovitis longitudinally (risk ratio 1.30, 95% CI 1.16, 1.46). Results were similar for IA calcification in the cartilage, meniscus, and capsule.

Conclusion: CT-detected IA calcification in various tissues was associated with the presence of joint inflammation on MRI over 2 years.