Botulinum toxin A as a chemoprotective adjunct following proximal hamstring tendon avulsion repair: a retrospective case series

BACKGROUND: Proximal hamstring tendon avulsions represent severe injuries that often require surgical repair. Postoperative failure and prolonged immobilization remain clinical challenges. Botulinum toxin A (BoNT-A) has been proposed as a chemoprotective adjunct to reduce muscle tension and protect tendon repairs. Evidence in adult populations remains limited. The aim of this article is to describe the feasibility, safety profile, and preliminary functional outcomes of BoNT-A administration as an adjunct to surgical repair of complete proximal hamstring tendon avulsions in adults.METHODS: In this retrospective case series, five adult patients with complete proximal hamstring tendon avulsions underwent surgical repair between 2019 and 2021. All patients received three ultrasound-guided intramuscular injections of BoNT-A (3 IU/kg) prior to surgery. Demographic and clinical data were retrospectively collected. At final follow-up, functional outcomes were assessed using the Perth Hamstring Assessment Tool (PHAT), and return-to-sport status was recorded. Complications were documented descriptively.RESULTS: At a mean follow-up of two years, all patients achieved full range of motion and reported no subjective weakness. The mean PHAT score was 91.2±8.3. All patients returned to their pre-injury level of activity at a mean of four months postoperatively. One patient reported partial sciatic nerve hypoesthesia, which resolved without intervention. No re-ruptures were observed.CONCLUSIONS: In this small retrospective case series, good outcomes were observed with the adjunctive use of BoNT-A in proximal hamstring tendon repair. These preliminary findings support further prospective controlled studies to evaluate the potential role of chemoprotection in proximal hamstring repair.