Background Joint destruction in RA includes both bone and cartilage lesions. By X-ray examination, cartilage destruction is evaluated as a joint space narrowing (JSN). However, joint space narrowing is not a direct evaluation of cartilage.
Objectives The aim of the study was to examine the finger joint cartilage by ultrasound (US) imaging and to compare it with JSN score in relation to clinical relevance.
Methods We enrolled 27 RA patients in low disease activity or clinical remission (DAS28-CRP <2.7) and 21 healthy controls in this study. The cartilage thickness (CT) of metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of 2nd to 5th fingers was bilaterally visualized and measured from a dorsal view, with approximately 90 degrees flexion. In addition, JSN of finger were scored by van der Heijde- modified Sharp method.
Results In patients with RA, CT in MCP joints ranged from 0.0 to 0.8 mm (median 0.4 mm), and CT in PIP ranged from 0.0 to 0.4mm (median 0.2mm), respectively. The sum of total CT from 8 fingers ranged from 2.7 to 6.8 mm (median 4.7 mm), and there was a significant difference in CT, but not in JSN score, between male and female patients (5.6 versus 4.6, respectively, p=0.005). Healthy controls had the sum of total CT significantly thicker as compared with RA (p≤0.001). Importantly, CT was well correlated with JSN (r=-0.696, p<0.001). Although CT was not correlated with age, disease duration, DAS28-CRP, functional disability score, positivity of rheumatoid factor and anti-CCP-antibody, CT was reduced in RA patients with elevated serum matrix metalloproteinase-3 (MMP-3) values compared with those with normal MMP-3 (3.9 versus 5.0, p=0.015).
Conclusions The US method of direct visualization and quantification of cartilage in MCP and PIP joints can be valid and useful in RA, and our results may support the importance of MMP-3 in the pathophysiology of cartilage destruction.
Disclosure of Interest None declared