Shear Wave Elastography Assessment of Achilles Tendon Stiffness in Asymptomatic Patients with Psoriatic Arthritis

Objectives: We aimed to evaluate Achilles tendon stiffness characteristics in asymptomatic patients with psoriatic arthritis (PsA) using shear wave elastography (SWE). Methods: In this prospective case-control study, 34 asymptomatic PsA patients and 34 age- and sex-matched healthy controls underwent bilateral Achilles tendon evaluation with grayscale ultrasonography and SWE. Tendon thickness was measured 3 cm proximal to the calcaneal insertion. Shear-wave velocity (m/s) and Young's modulus (kPa) were obtained under standardized acquisition conditions, including five-star motion stability and ≥90% reliability. Results: Achilles tendon morphology and thickness did not differ between PsA patients and controls (p > 0.05). In contrast, SWE demonstrated higher tendon stiffness in the PsA group. Mean shear-wave velocity was significantly greater in PsA patients for both the left (4.89 ± 2.52 m/s vs. 3.23 ± 0.41 m/s; p < 0.001) and right tendons (4.88 ± 1.94 m/s vs. 3.12 ± 0.30 m/s; p < 0.001), with corresponding increases in Young's modulus (all p < 0.001). SWE demonstrated good group discrimination, with shear-wave velocity achieving AUC values of up to 0.90 in differentiating PsA patients from healthy controls. Conclusions: SWE may reflect biomechanical tendon alterations in PsA, even in the absence of clinical symptoms, and may serve as a complementary imaging tool in the assessment of tendon involvement.