Relationship between tendon elastography and clinical and ultrasound enthesitis scores in patients with psoriasis or psoriatic arthritis

Abstract

Aim: To determine the existence of a correlation between the elastographic study of the patellar and Achilles tendons and the enthesis evaluation in patients with psoriasis with or without psoriatic arthritis. Methods: Observational, cross-sectional study. Patients with psoriasis, psoriatic arthritis and healthy controls were included. The elastography results of the patellar and Achilles tendons of the non-dominant leg of the three groups were compared and tested for correlation with the Madrid Sonographic Enthesis Index (MASEI) score, as well as an entheses clinical evaluation score [Spondyloarthritis Research Consortium of Canada (SPARCC)]. Results: Forty-eight patients were included, 24 with psoriasis and 24 with psoriatic arthritis, as well as 48 healthy controls. Patients with psoriatic arthritis had a higher clinical enthesitis score than patients with psoriasis (8.0 vs. 1.0, P < 0.001). The mean (standard deviation) or median (25–75 percentile) of control subjects patellar and Achilles’ tendon stiffness, 127.8 kPa (18.5 kPa) and 198.0 kPa (183.2–212.0 kPa) were significantly higher than observed in patients with psoriatic arthritis, 119.2 kPa (19.7 kPa) and 184.8 kPa (175.5–193.9 kPa; P < 0.001 and P = 0.018, respectively). A strong inverse correlation between MASEI score and the patellar and Achilles’ tendon stiffness was also detected (Spearman’s Rho coefficient of –0.813 and –0.941, respectively). Conclusions: Patients with psoriatic arthritis present less stiffness in those load-bearing tendons than healthy controls. There is an inverse correlation between the enthesis involvement demonstrated by ultrasound and the elastography of these tendons. Tendon elastography can be considered a useful quantitative tool in assessing patients with psoriatic disease.