Primary augmentation of percutaneous repair with flexor hallucis longus tendon for Achilles tendon ruptures reduces tendon elongation and may improve functional outcome

Abstract

Purpose: Achilles tendon ruptures (ATR) result in loss of strength and function of the gastrosoleus-Achilles tendon complex, probably because of gradual tendon elongation and calf muscle atrophy, even after surgical repair. Flexor hallucis longus (FHL) augmentation not only reinforces the repair and provides new blood supply to the tendon, but also protects the repair, internally splinting the repaired Achilles tendon, maintaining optimal tension. We prospectively compared the clinical outcomes of patients with acute ATR, managed with either percutaneous repair only or percutaneous repair and FHL augmentation.

Methods: Patients with acute ATR undergoing operative management were divided into two groups. Thirty patients underwent percutaneous repair under local anesthesia, and 32 patients underwent percutaneous repair augmented by FHL tendon, harvested through a 3 cm longitudinal posteromedial incision, and transferred to the calcaneus, under epidural anesthesia. All patients were treated by a single surgeon between 2015 and 2019 and were followed prospectively for 24 months.

Results: The percutaneous only group was younger than the augmented one (35.4 ± 8.0 vs 40.4 ± 6.6 years, p = 0.01). In the augmented group, 25 patients stayed overnight and only 5 were day cases, whereas in the percutaneous only group 4 patients stayed overnight and 28 of them were day cases (p < 0.001). The duration of the procedure was significantly longer in the augmented group (38.9 ± 5.2 vs 13.2 ± 2.2 min, p < 0.001). At 24 months after repair, the Achilles tendon resting angle (ATRA) was better in the augmented group (-0.5 ± 1.7 vs -4.0 ± 2.7, p < 0.001), as was Achilles tendon rupture score (ATRS) (91.7 ± 2.2 vs 89.9 ± 2.4, p = 0.004). Calf circumference of the injured and the non-injured leg did not differ between the groups, as did the time interval to single toe raise and the time interval to walking in tiptoes. Although plantarflexion strength of the operated leg was significantly weaker than the non-operated leg in both groups, the difference in isometric strength of the operated leg between the groups was not significant at 24 months (435 ± 37.9 vs 436 ± 39.7 N, n.s.).

Conclusion: Percutaneous repair and FHL tendon augmentation may have a place in the management of acute Achilles tendon ruptures, reducing tendon elongation and improving functional outcome.

Level of evidence: Level II.

Keywords: Achilles tendon; Acute; FHL; Percutaneous repair; Rupture.