Implantation of a Canine Total Ankle Replacement Prosthesis Using a Lateral Surgical Approach is Accurate and Leads to a Stable Joint

Objective This study aimed to determine if canine total ankle replacement (cTAR) can be performed using a lateral surgical approach by comparing implant orientation, limb orientation and tarsocrural stability after implantation using a lateral or medial approach.Study Design Ten cadaveric limbs from five large-breed dogs were implanted with a cTAR prosthesis using a medial or a lateral approach. Caudocranial and mediolateral radiographs were obtained. Joint orientation, limb orientation, angular tarsocrural stability (varus and valgus laxity) and rotational tarsocrural stability (internal and external rotational laxity) were measured before and after implantation and compared. Polar gaps around cTAR components were measured.Results Before implantation, mean valgus laxity was 1.8 degrees larger in limbs which were implanted with a cTAR prosthesis using a lateral approach than in limbs implanted using a medial approach. After a lateral approach, mean valgus laxity was 4.4 degrees larger (7.2 degrees) than before (2.8 degrees), and mean external rotational laxity was 5.4 degrees larger (10.7 degrees) than before (5.3 degrees). After a medial approach, mean external rotational laxity was 6.7 degrees larger (11.6 degrees) than before (4.9 degrees). The mean angular laxity was 6.0 degrees larger after a lateral approach (15.5 degrees) than a medial approach (9.5 degrees). Significant differences among other measurements collected after a lateral or medial approach were not identified.Conclusion A cTAR prosthesis can be implanted using a lateral approach and result in a properly oriented tarsocrural joint that is rotationally stable and has slight angular laxity.