Tenodesis reconstruction for chronic ankle instability: graft considerations and structures at risk with tunnel placement

Lateral ankle ligament surgical reconstruction can take many forms, including anatomic and nonanatomic reconstructions. The nonanatomic reconstructions require the use of autograft or allograft tendons to recreate the vectors of the injured anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). The purpose of this study was to determine the minimum, maximum, and average graft length requirements for a modified Chrisman-Snook procedure. The structures at risk during drilling of the bone tunnels were documented to guide recommendations for tunnel placement. Modified Chrisman-Snook lateral ligament reconstructions were performed on 10 cadaveric below-the-knee specimens, with no known pathology. Transosseus tunnels were placed through and through the fibula, talus, and calcaneus at the origin and insertion sites of the ATFL and CFL. The minimum, maximum, and average graft length requirements were 91 mm, 170 mm, and 120.7 ± 23.84 mm, respectively. The overall average graft requirement was approximately 120 mm. The length of graft was correlated with the height of the patient. Medial structures that were directly encountered, in at least one specimen, with the transosseus tunnels included the tibial nerve, tibial artery and flexor hallucis longus tendon. The posterior tibial nerve was the structure at greatest risk. The length of the graft, when performing the modified Chrisman-Snook, should measure approximately 120 mm, but considerable variability exists depending on the size of the patient. To avoid injury to medial structures, the transosseus tunnels should be made using either a blind hole technique or guide wire to avoid perforating the medial cortex.

Cadaveric, Level V.