The thickening of flexor tendons pulleys: a useful ultrasonographical sign in the diagnosis of psoriatic arthritis.

PURPOSE: To investigate the frequency of thickening of pulleys for flexor tendons in patients with early arthritis in their hands, and to evaluate it as a predictive sign of PsA.

METHODS: A prospective observational study involving 228 consecutive patients presenting with recent onset of arthritis in their hands was conducted at rheumatology outpatient clinics in the Veneto region of Italy between October 2014 and September 2017. Diabetic patients were excluded because of the high frequency of trigger finger. The final diagnosis of the rheumatologist delivered after 12 months of follow-up, was considered as the gold standard for the analysis of diagnostic accuracy.

RESULTS: Twenty-two patients were excluded from the study because of diabetes. A total of 86 patients with thickening of A1 pulleys in flexor tendons and 120 without were evaluated. Pulley thickness was significantly associated with a family history of psoriasis (18/86 vs 3/120, p ˂ 0.001) and diabetes (9/86 vs 4/120, p = 0.036), and with a personal history of cutaneous psoriasis (25/86 vs 10/120, p ˂ 0.001), psoriatic onychopathy (7/86 vs 2/120, p = 0.028), lower back pain (22/86 vs 11/120, p = 0.001), Dupuytren's disease (7/86 vs 2/120 p = 0.028) and De Quervain tenosynovitis (4/86 vs 0/120, p = 0.028). In isolation, this sign had a good sensitivity rate (80%). The specificity rate for the disease was barely significative (71%), with an LR+ of 2.71 for PsA.

CONCLUSIONS: The thickening of the pulleys in the flexor tendons is an easy-to-detect sign with good sensitivity for the diagnosis of PsA. Its specificity and positive predictive value are not very high; however, if it is included in a complete classification process, sonographers should report it during hand evaluations of patients with arthritis.