Ultrasonography (US) is a sensitive tool for detecting erosions in patients with RA. The wrist is usually involved in the RA process, where the distal ulna with its superficial localization is easily accessible for US examination. In this longitudinal study, we wanted to examine the presence, localization and development of erosions at the distal ulna by US in patients with recent onset RA, and to analyse whether erosions at this localization are associated with joint damage in hands assessed by conventional radiography (CR) and MRI.
Seventy patients with recent onset RA (median disease duration 106 days) were examined by US of the distal ulna, in addition to hand radiography [assessed by van der Heijde-modified Sharp score (vdHSS)] and MRI of the wrist [assessed by RA MRI scoring (RAMRIS) erosion score]. Twelve months later 58 patients were re-assessed.
US detected erosions at the distal ulna in 11% of the patients at baseline and 24% at follow-up (the majority of erosions were at the ulnar side). Logistic regression analyses showed the presence of erosions at baseline to be associated with baseline RAMRIS erosion score (P < 0.001), and at follow-up to RAMRIS erosion score (P = 0.02) and vdHSS (P = 0.008).
A significant number of patients had US erosions at the distal ulna at baseline, with increased prevalence after 1 year. The US-detected erosions were associated with structural joint damage in hands assessed by both MRI and CR. US of the distal ulna could thus give useful clinical information.