RETROCALCANEAL BURSITIS IN SPONDYLOARTHROPATHY - ASSESSMENT BY ULTRASONOGRAPHY AND MAGNETIC-RESONANCE-IMAGING

Objective. To establish by magnetic resonance imaging (MRI) and ultras onography (US) the frequency of retrocalcaneal bursa involvement in Ac hilles enthesitis of spondyloarthropathy (SpA) and to compare the resu lts of the 2 examinations. Methods. Nineteen Achilles tendons with sev ere enthesitis and 9 normal tendons of 14 patients meeting the Amor cr iteria for SpA were examined by MRI and US.Results. Both MRI and US sh owed a significant increase in the mean Achilles tendon thickness in t he pathologic legs compared to the normal legs both at the superior ca lcaneal surface and 3 cm above. MRI showed retrocalcaneal bursitis in 14 (73.7%) of 19 pathologic legs and superficial bursitis in 2 (10.5%) . US showed fluid collection only in 7 of 14 retrocalcaneal bursae pos itive on MRI, and failed to show fluid in the 2 superficial bursae inv olved. Using MRI as the gold standard, US showed 50% sensitivity and 1 00% specificity for retrocalcaneal bursa involvement and lacked sensit ivity for superficial bursitis. Conclusion. Achilles tendon involvemen t in SpA is not only a disease of the enthesis but also of the adjacen t bursae.