Enthesitis in psoriatic arthritis – is the clinical evaluation enough?

Abstract

Objective. In this study, we aim to evaluate the frequency of enthesitis in psoriatic arthritis (PsA), using musculoskeletal ultrasonography (MSUS) and to determine to what extent it is correlated to clinical spontanous or provoked pain, disease activity and biologic inflammatory markers. Methods. 320 entheses, belonging to 20 PsA patients, were evaluated clinically and MSUS. For each patient, the medical history form included questions regarding spontaneous pain, targeted to 16 entheseal sites. Then, a thorough enthesis clinical exam was performed, evaluatig pain upon pressure (digital pressure on the enthesis overlying skin). Two Esaote My Lab machines were used, with 6-12/8-18 MHz linear probes. All evaluations were performed by the same clinician/ultrasonographer. Results. The Achilles, followed by the quadriceps tendons were the most affected by MSUS-detected enthesitis, both in gray scale (GS) (100%, 75% respectively) and power Doppler (PD) (40%, 35% respectively), while the proximal patellar tendon (35% GS, 25% PD), the plantar fascia (40% GS, 25% PD) and the flexor tendons (45% GS, 25% PD) were the least affected. Ultrasound abnormalities were found in up to 68.4% of the asymptomatic entheses, with high variation between the entheseal sites. The number of ultrasound-detected enthesitis for each patient was significantly correlated with the patient’s global assessment for DAPSA and also with the CRP levels, in this lot of patients with high disease activity. Conclusions. In PsA, the entheses involvement is a central feature, underscored in this study by the high percentages of both GS and PD abnormalities, even in the least affected entheseal sites. There is a low correlation between clinical symptoms and imaging signs of enthesitis in PsA, which proves the need for an imagistic enthesitis score in the diagnostic process, in order to establish the full extent of the disease and a more personalised therapeutic plan.

Keywords

• psoriatic arthritis
• enthesitis
• musculoskeletal ultrasonography