Background It was previosly shown that metacarpal cartilage thickness (MCT) as assessed by ultrasound (US) correlates with both radiographic joint space width (JSW) and joint space narrowing (JSN) in the metacarpophalangeal joints (MCP) of patients with rheumatoid arthritis (RA).
Objectives To correlate change in MCT with change in radiographic JSW and JSN in a longitudinal study of patients with RA.
Methods We performed US examination of 19 consecutive outpatients with RA fulfilling the 2010 ACR/EULAR classification criteria with recent hand X-rays. Metacarpal cartilage of MCP 2–5 was assessed bilaterally by US at baseline and after 3 years in mm with an integrated caliper on static images (Figure 1A). JSN was evaluated on X-rays taken <1 year before the sonographic assessment as well as within 6 months of the second sonographic assessment by the van der Heijde modified Sharp method (vdHS). In addition, JSW was measured on the very same hand X-rays using an integrated calliper (Figure 1B). The relationship between sonographic and radiographic measures was investigated by Spearman correlation.
Results Over the study period of 3 years a mean change of MCT of 0.00±0.01mm, was paralleled by a mean change of JSW of -0.08±0.20mm and a change of 0.12±0.37 in the JSN component of the vdHS. Change in MCT correlated with change in JSW (r: 0.37; p:<0.001) as well as with change in JSN (r:-0.26; p:<0.001). We could also demonstrate correlation between the two radiographic measures (r: 0.33; p:<0.001). Change in erosion did not correlate with either sonographic MCT or with the radiographic measures.
Conclusions Change in sonographic cartilage thickness correlates with radiographic measures of joint space narrowing in the MCP joints of RA patients over time. Thus, ultrasound may be a valid tool for the longitudinal assessment of metacarpal cartilage in RA patients, but also the radiographic assessments appear to reflect “true” cartilage dimensions.
Disclosure of Interest None declared