Shear wave elastography of the Achilles tendon for detecting subclinical tendon changes in adults receiving fluoroquinolone therapy

This is the authors' abstract. We don't add key points for this paper.

Can Shear Wave Elastography (SWE) identify early biomechanical changes in the Achilles tendon before clinical symptoms appear in patients treated with fluoroquinolone antibiotics? Fluoroquinolones remain among the most widely prescribed antimicrobial agents worldwide, yet their association with tendon disorders, particularly Achilles tendinopathy and rupture, poses a persistent clinical concern. Conventional B-mode ultrasonography can depict structural abnormalities such as tendon thickening and hypoechoic regions, but these findings typically emerge only after considerable tissue damage has occurred. SWE offers a quantitative, non-invasive measure of tissue stiffness that may reveal subclinical alterations in tendon mechanical properties at an earlier stage. This prospective observational research enrolled 142 adults at a single centre in Graz, Austria, between March 2023 and January 2024. Sixty-eight participants who were prescribed a fluoroquinolone (levofloxacin or ciprofloxacin) for at least seven days formed the exposure group, while 74 age- and sex-matched adults who did not receive any fluoroquinolone served as controls. Bilateral Achilles tendon SWE and B-mode ultrasound examinations were performed at baseline and at six weeks. The primary outcome was the change in shear wave velocity (SWV) across the proximal, mid-portion, and distal segments of the tendon. Secondary outcomes included tendon thickness, echotexture grading, and patient-reported tendon symptoms. After six weeks, the fluoroquinolone group showed a statistically marked reduction in SWV at all three tendon segments compared with controls (proximal: 38.7 vs 47.2 kPa, P <0.001; mid-portion: 31.4 vs 43.8 kPa, P<0.001; distal: 42.1 vs 49.6 kPa, p=0.003), whereas B-mode findings remained unremarkable in 87.3% of the fluoroquinolone group. These results suggest that SWE can detect subtle biomechanical softening of the Achilles tendon in fluoroquinolone-treated adults before conventional imaging changes become apparent, and may serve as a monitoring tool for patients at risk of drug-induced tendinopathy.