Retrocalcaneal Bursitis Precedes or Accompanies Achilles Tendon Enthesitis in the Early Phase of Rheumatoid Arthritis

The consecutive reports and stored images of ultrasound examinations for 100 symptomatic ankles of 74 patients with rheumatoid arthritis (RA) were reviewed for the presence or absence of retrocalcaneal bursitis (RCB) and Achilles tendon enthesitis (ATE). The ankles were classified into 4 categories based on the presence or absence of RCB or ATE. The number of RCB(-)/ATE(-), RCB(+)/ATE(-), RCB(+)/ATE(+), and RCB(-)/ATE(+) ankles was 62, 16, 12, and 10, respectively. When classifying patients into early RA and established RA, the percentage of RCB(-)/ATE(+) ankles with early RA was significantly lower than that with established RA (P = .00595). The disease duration was significantly longer in the RCB(-)/ATE(+) ankles than in the RCB(+)/ATE(-) ankles (median [interquartile range]: 15.29 [8.69] months vs 3.6 [3.06] months, P = .0247). It was speculated that RCB precedes or accompanies ATE in the early phase of RA, which suggests that entheseal inflammation in RA arises from synovial tissues.