Strain Ultrasound Elastography in the Achilles Tendon of Ankylosing Spondylitis Patients Treated With Anti-TNF-α: A Preliminary Study

BACKGROUND/AIM:To compare patients affected by ankylosing spondylitis (AS) treated with anti-TNF-α for two years with controls in terms of Achilles tendon stiffness, ultrasound structure and thickness.PATIENTS AND METHODS:B-mode ultrasound evaluation and strain ultrasound elastography were performed in longitudinal and transverse planes on 22 Achilles tendons of 11 AS patients and 26 of 13 controls.RESULTS:There were no significant differences in thickness and stiffness of the Achilles tendon between AS patients and controls, except for an increased thickness in the middle third of the tendon in the AS patients (p=0.04). The Achilles tendon stiffness ratio of AS patients was 1.02±0.36 vs. 1.14±0.38 in the controls (p=0.2).CONCLUSION:AS patients had an Achilles tendon thickness greater than controls at the middle third, but no difference in the stiffness was found among them. Strain ultrasound elastography may be useful to exclude early changes in mechanical properties of tendons.KEYWORDS:Achilles tendon; ankylosing spondylitis; anti-TNF-α therapy; elastography; ultrasound