FRI0594 Retrocalcaneal bursitis precedes or accompanies achilles tendon enthesitis in the early phase of rheumatoid arthritis
Authors: T. Suzuki, Y. Hidaka, Y. Seri
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> We had reported the frequencies of various pathologies detected by ultrasound (US) in symptomatic ankles and heels in rheumatoid arthritis (RA) patients <sup>1</sup>. Through that study, we recognised that Achilles tendon (AT) involvement is not rare in RA, because retrocalcaneal bursitis (RCB), AT enthesitis, AT tendonitis and AT paratendonitis was detected in 27%, 22%, 13%, and 6% of the symptomatic ankles examined, respectively. Recently, it has been reported that RA and SpA patients did not differ in entheseal abnormalities seen on US <sup>2</sup>. However, we think that there is fundamental difference between the inflammation of synovio-entheseal complexes in RA and that in SpA. <h3>Objectives</h3> This study aims to investigate characteristics of entheseal abnormalities in RA by evaluating the association between US-detected RCB or AT enthesitis and clinical data. <h3>Methods</h3> We reviewed consecutive records of 100 ankles in 74 RA patients (fulfilling the 2010 criteria) who underwent US examination of symptomatic ankles because of clinical need. The patients consist of 52 women and 22 men (median age 63.3 years, range 26–83 years) with median disease duration of 4.2 months (range 0.23 months to 19.4 years), as described previously. 55/74 (74%) of them were positive for RF and/or ACPA. The association between presence of RCB or AT enthesitis in a narrow definition (i.e., insertional tendinitis) and clinical data were analysed using Fisher's exact test or Mann-Whitney <i>U</i> test. <h3>Results</h3> Among the overall 100 ankles, the frequency of RCB-positive/AT enthesitis-negative ankles, that of RCB-positive/AT enthesitis-positive ankles and that of RCB-negative/AT enthesitis-positive ankles were all more than 10%. Interestingly, the frequency of RCB-negative/AT enthesitis-positive ankles among the 62 ankles with early RA (disease duration &lt;6 months) was significantly lower as compared to that among the 38 ankles with established RA (p=0.00595). Similarly, the frequency of RCB-negative/AT enthesitis-positive ankles among the 58 ankles of untreated patients was lower as compared to that among the 42 ankles of already-treated patients. The disease duration was significantly longer in the RCB-negative/AT enthesitis-positive ankles than in the rest of the ankles (43.8±74.6 months vs. 16.7±35.3 months, p=0.0179). <h3>Conclusions</h3> McGonagle et al. advocated the concept of synovio-entheseal complex and suggested that the inflammation occurs primarily at the enthesis and spreads to adjacent synovial tissues such as bursae in SpA patients. Our cross-sectional data indirectly indicated that RCB precedes or accompanies AT enthesitis in a narrow definition in the early phase of the RA, suggesting that the inflammation around the enthesis of RA patients occurs primarily at the synovial tissues and spreads to the enthesis in an opposite way. In addition, the isolated AT enthesitis without RCB in the established and/or treated RA patients may suggest several possibilities as follow: 1. Enthesitis is more refractory to RA treatment than bursitis; 2. Enthesitis is partially due to the degenerative changes related to damages and deformities caused by RA synovitis; 3. US-detected enthesitis in RA basically represents repair process rather than ongoing inflammation. <h3>References</h3> [1] Suzuki T, Okamoto A. Clin Exp Rheumatol201;31(2):281–4. [2] Ebstein E, et al. Joint Bone Spine2017Dec 9. [Epub ahead of print]. <h3>Disclosure of Interest</h3> None declared