Anterior talofibular ligament ruptures, part 2: biomechanical comparison of anterior talofibular ligament reconstruction using semitendinosus allografts with the intact ligament.

BACKGROUND: Anatomic reconstructions of the lateral ankle ligaments with grafts have been proposed for patients with generalized ligamentous laxity, long-standing instability with attenuated native tissues, varus hindfoot misalignment, or failed prior lateral ligament surgery and for very large patients or elite athletes because of increased demands.

HYPOTHESIS: Anatomic reconstruction of the anterior talofibular ligament (ATFL) using a semitendinosus allograft fixed with biocomposite interference fit screws would have similar biomechanical properties to the intact ATFL at time zero in a cadaveric model.

STUDY DESIGN: Controlled laboratory study.

METHODS: Allograft reconstruction of the ATFL was performed in 6 fresh-frozen cadaveric ankles. The specimens were loaded to failure to determine the strength and stiffness of the reconstruction and compared with data from 6 cadaveric specimens with intact ATFLs.

RESULTS: The mean ultimate load to failure of the allograft reconstruction (170.7 ± 54.8 N) was not significantly different from that of the intact ATFL (154.0 ± 63.7 N). The mean stiffness of the allograft reconstruction (23.1 ± 9.3 N/mm) was also not significantly different from that of the intact ATFL (14.5 ± 4.4 N/mm).

CONCLUSION: Anatomic reconstruction of the ATFL with allografts demonstrated similar strength and stiffness to the native ligament at time zero in a fresh-frozen cadaveric model.

CLINICAL RELEVANCE: This technique of anatomic reconstruction of the ATFL with allografts has biomechanical validation for use in clinical situations where a Broström repair of the lateral ankle ligaments is unlikely to be successful or has previously failed.