Tendon friction rubs in systemic sclerosis: a possible explanation--an ultrasound and magnetic resonance imaging study.

OBJECTIVE: To assess the tendon and joint involvement at wrists and ankles of patients suffering from diffuse SSc and to identify the morphological substrate of tendon friction rubs (TFRs).

METHODS: Fifteen consecutive patients suffering from diffuse SSc were included. All patients had two musculoskeletal US (MSUS) examinations of the wrists and ankles. MRI was performed at the most affected joints as detected by MSUS and in all sites in which TFRs were present.

RESULTS: No clinically overt arthritis or tenosynovitis was detected in the wrists and/or ankles prior to MSUS. Synovitis, tenosynovitis and tendon tear were identified in 8, 4 and 2 of 15 patients, respectively, by both MSUS and MRI. At entry, 5 patients had palpable TFRs (4 bilateral and 1 unilateral) and 10 patients did not. Tenosynovitis was more frequently found in ankles with TFRs (3/9) than in those without TFRs (3/21), although the difference was not statistically different (P = 0.3). Using MRI, deep connective tissue infiltrates surrounding tendons were present in all sites with TFRs but in only one patient without TFRs.

CONCLUSION: Both MSUS and MRI are effective in detecting synovitis and tenosynovitis in diffuse SSc patients. Tenosynovitis, synovitis and thickened retinacula are not infrequently seen in these patients. Our data suggest that juxta-tendinous connective tissue infiltrates might be the morphological substrate of tendon friction rubs, which may thus be a misnomer for tissue friction rubs.