The effects of percutaneous ultrasound tenotomy on chronic tendinopathy in a rabbit Achilles’ tendon model

Abstract

Objective: Chronic tendinopathy is debilitating and significantly limits physical function and quality-of-life. For chronic tendinopathy recalcitrant to conservative approaches, percutaneous ultrasound tenotomy (PUT) has become a common minimally-invasive therapy. To clarify the histopathological effects of PUT, we assessed the cellular and tissue-level effects of PUT in an animal model of chronic tendinopathy.Design: This within-subject randomized-controlled study treated the bilateral Achilles’ tendons of 10 skeletally-mature, male New Zealand white rabbits with Kartogenin (KGN) beads to mimic chronic tendinopathy and allowed free cage activity for six weeks. One randomly-selected Achilles’ tendon per rabbit underwent sonographically-guided PUT, using 60 s of ultrasound energy. Six weeks post-procedure, the bilateral Achilles’ tendons were harvested and histologically graded.Results: Treated and untreated sides were compared using paired t-tests and mixed models. There were no statistically-significant differences in collagen arrangement, cellularity, or ground substance deposition (all p>0.16). Bonar scores for the most superficial level (95% CI) and the whole tendon (95% CI) were 1.7 (0.6, 2.8) and 0.9 (0.0, 1.9) points lower on the PUT side compared with the untreated side (p=0.037 and p=0.059 respectively). Conclusion: These findings provide evidence that PUT stimulates Histopathologic improvement in collagen formation and organization in the setting of chronic tendinopathy.