Synovitis and radiographic progression in non-erosive and erosive hand osteoarthritis: is erosive hand osteoarthritis a separate inflammatory phenotype?

OBJECTIVE: To compare the prevalence of synovitis, pain and radiographic progression in non-erosive and erosive hand osteoarthritis (HOA), and to explore whether the different rate of disease progression is explained by different levels of synovitis and structural damage. DESIGN: We included 31 and 34 participants with non-erosive and erosive HOA at baseline, respectively. Using Generalized Estimating Equations, we explored whether participants with erosive HOA had more synovitis (by MRI, ultrasound and clinical examination) independent of the degree of structural damage. Similarly, we explored whether pain at baseline and radiographic progression after 5 years were higher in erosive HOA, independent of the levels of synovitis and structural damage. All analyses were adjusted for age and sex. RESULTS: Power Doppler activity was found mainly in erosive HOA. Participants with erosive HOA demonstrated more moderate-to-severe synovitis, assessed by MRI (OR = 1.73, 95% CI 1.11-2.70), grey-scale ultrasound (OR = 2.02, 95% CI 1.25-3.26) and clinical examination (OR = 1.80, 95% CI 1.44-2.25). The associations became non-significant when adjusting for more structural damage. The higher frequency of joint tenderness in erosive HOA was at least partly explained more structural damage and inflammation. Radiographic progression (OR = 2.53, 95% CI 1.73-3.69) was more common in erosive HOA independent of radiographic HOA severity and synovitis (here: adjusted for grey-scale synovitis by ultrasound). CONCLUSION: Erosive HOA is characterized by higher frequency and more severe synovitis, pain and radiographic progression compared to non-erosive HOA. The higher rate of disease progression was independent of baseline synovitis and structural damage.

Enhanced angiogenesis and increased bone turnover characterize bone marrow lesions in osteoarthritis at the base of the thumb.

OBJECTIVES: Little is known about tissue changes underlying bone marrow lesions (BMLs) in non-weight-bearing joints with osteoarthritis (OA). Our aim was to characterize BMLs in OA of the hand using dynamic histomorphometry. We therefore quantified bone turnover and angiogenesis in subchondral bone at the base of the thumb, and compared the findings with control bone from hip OA. METHODS: Patients with OA at the base of the thumb, or the hip, underwent preoperative MRI to assess BMLs, and tetracycline labelling to determine bone turnover. Three groups were compared: trapezium bones removed by trapeziectomy from patients with thumb base OA (n = 20); femoral heads with (n = 24); and those without (n = 9) BMLs obtained from patients with hip OA who underwent total hip arthroplasty. RESULTS: All trapezium bones demonstrated MRI-defined BMLs. Compared with femoral heads without BMLs, the trapezia demonstrated significantly higher bone turnover (mean sd 0.2 (0.1) versus 0.01 (0.01) µm3/µm2/day), mineralizing surface (18.5% (13.1) versus 1.4% (1.3)) and vascularity (5.2% (1.1) versus 1.2% (0.6)). Femoral heads with BMLs exhibited higher bone turnover (0.3 (0.2) versus 0.2 (0.1) µm3/µm2/day), a higher mineralization rate (26.6% (10.6) versus 18.6% (11.9)) and greater trabecular thickness (301.3 µm (108) versus 163.6 µm (24.8)) than the trapezia. CONCLUSION: Bone turnover and angiogenesis were enhanced in BMLs of both the thumb base and hip OA, of which the latter exhibited the highest bone turnover. Thus, the increase in bone turnover in weight-bearing joints like the hip may be more pronounced than less mechanically loaded osteoarthritic joints demonstrating BMLs. The histological changes observed may explain the water signal from BMLs on MRI.Cite this article: M. Shabestari, N. J. Kise, M. A. Landin, S. Sesseng, J. C. Hellund, J. E. Reseland, E. F. Eriksen, I. K. Haugen. Enhanced angiogenesis and increased bone turnover characterize bone marrow lesions in osteoarthritis at the base of the thumb. Bone Joint Res 2018;7:406-413. DOI: 10.1302/2046-3758.76.BJR-2017-0083.R3.