Combined radiographic and ultrasound evaluations to decipher joint involvement in the hands of patients with systemic sclerosis.

Objective: The objective of this study was to explore the etiologies and contributing factors of synovial and tenosynovial involvement in SSc, as well as to assess the phenotype of patients with these synovial and tenosynovial features.

Methods: 171 SSc patients with hand manifestations (either vascular, skin or joint manifestations) who underwent standard X-rays of both hands and hand ultrasound (US), were included. Two independent evaluators recorded the presence or absence of acro-osteolysis, calcinosis, microcrystalline and degenerative rheumatisms, including osteophytosis on X-Rays. The presence of synovitis and tenosynovitis (active or fibrotic) was assessed through US by a third evaluator, blinded for X-ray parameters.

Results: In multivariate analysis, the characteristics associated with active synovitis and tenosynovitis were CRP>10mg/L (p = 0.013), fibrotic tenosynovitis on US (p = 0.005), anti-RNA polymerase III antibodies (p = 0.043) and poly-osteophytosis on hand X-rays (p = 0.001). After exclusion of patients with RA (n = 5) and/or poly-osteophytosis (n = 53), 14 remaining patients (12.7%) had active synovitis and/or tenosynovitis on US. In multivariate analyses, parameters associated with active synovitis and/or tenosynovitis in this selected population were scleroderma renal crisis (p = 0.012) and fibrotic tenosynovitis on US (p < 0.001).

Conclusion: Our study confirms that osteophytosis is a significant contributor of joint involvement in SSc patients based on real life data. After exclusion of potential confounders, more than 10% of SSc patients still had active synovitis and/or tenosynovitis on US, providing indirect evidence for the existence of a specific SSc-related synovial and/or tenosynovial involvement.