Decreased femoral cartilage thickness in patients with systemic sclerosis

BACKGROUND:: Systemic sclerosis (SSc), or scleroderma, is a severe connective tissue disease. Although musculoskeletal involvement is frequent and causes significant functional disability in patients with SSc, articular cartilage thickness has not been previously investigated. The aim of this study was to compare the femoral cartilage thickness (FCT) in patients with SSc with that of controls who were matched for age, body mass index and osteoarthritis prevalence. METHODS:: The thickness of femoral articular cartilage was measured by ultrasonography in patients and controls. Three midpoint measurements were taken from each knee: lateral femoral condyle (LFC), femoral intercondylar area and medial femoral condyle (MFC). RESULTS:: Forty female patients with SSc and 85 female controls were included. In patients with SSc, 18 (45.0%) had diffuse SSc, 18 (45.0%) had limited SSc, 1 (2.5%) had overlap (polymyositis) and 3 (7.5%) had SSc sine scleroderma. The mean FCT measurements of patients with SSc at MFC of the right and left knees (1.86 and 1.84 mm, respectively) and LFC of the left knee (1.93 mm) were statistically lower than in the controls (right and left MFC, 2.23 and 2.25 mm, respectively, P < 0.0001, and left LFC 2.15 mm, P = 0.026). CONCLUSIONS:: Patients with SSc had thinner femoral cartilage compared with controls. The underlying possible mechanisms of thin FCT may be multifactorial, and there may be many influencing factors like immune activation, vasculopathy, oxidative stress and synovial fibrosis or markers of cartilage degradation. The possible factors influencing the change in cartilage thickness or metabolism in patients with SSc require further research.