Ultrasonography Role in Evaluation of Achilles Tendon Enthesis in Reactive Arthritis Patients

Reactive arthritis is an inflammatory joint disease which develops after 1-4 weeks following an enteral, genital or ORL infection, with a higher frequency in HLA-B27 positive patients. As a group feature, enthesitis is defined as inflammation in bone insertions of tendons, ligaments and muscular fascia. Aims: the main object of this study was to demonstrate the importance of musculoskeletal ultrasonography in Achilles tendon evaluation in patients with reactive arthritis. Patients and methods: we designed a transversal, retrospective study which included 15 patients diagnosed, based on ESSG criteria, with reactive arthritis (ReA), in Rheumatology Department, Emergency County Hospital. From those 15 patients, 9 were positive for a genital infection with Chlamydia trachomatis and 6 patients with enteral infection, 2 with Shigella, respectively 4 with Yersinia. Healthy control group included 15 patients, with no inflammatory joint diseases. After clinical examination, all patients and controls underwent ultrasound (US) evaluation for Achilles tendon changes, using an Esaote MyLab 25 machine, with a linear high frequency probe (10-18 MHz), using EULAR recommendations and OMERACT definitions for enthesitis, tendinitis and erosions. The cutoff value for the Achilles tendon thickness was 5.29mm, as described by Balint et al. Results: We examined 30 Achilles tendons in 15 patients, with a mean age of 35,2years±10,19 standard deviation (SD) and 30 tendons in 15 controls with a mean age of 35,8 years ±12,00 SD. In both groups sex prevalence showed more males than females (66,66% males in controls vs. 60,00% in patients group). We found a statistic significant higher ESR and CRP in patients group, compared to controls (24,86mm/h vs. 11,8mm/h; 18.90mg/dl vs. 6.22mg/dl). Most frequent finding in patients group was retrocalcaneal bursitis (56.66%), followed by tendon thickening (46.66%), compared to control group in which we found more frequently osteophytes (36.66%) and calcifications (23.33%). Tendon thickness was significantly higher in the patients group compared to control group 5.30mm±1.39SD vs. 4.42mm±0.77SD, p=0.008). When compared to clinical examination, US found at least one change in all patients (100% vs. 40.0%). Conclusions: A higher prevalence of retrocalcaneal bursitis and tendon thickening were found in reactive arthritis patients compared to control group. The US found more changes compared to clinical examination and manage to discriminate between the types of changes found more frequently in inflammatory conditions.