Lateral Approach Versus Anterior Approach in Total Ankle Replacement

A minimum of 50 patients with ankle end-stage arthritis will be randomized in two parallel groups for surgery. One group will receive a total ankle replacement through an anterior approach and the other group a total ankle replacement via a lateral approach. Patients will be evaluated for a mean follow-up of two years in terms of complications, implant survival and functional results. One of the primary objectives of the study is analyzing the safety of the lateral and anterior approaches for total ankle replacement.

The anterior approach uses an interval between the anterior tibial tendon and the extensor digitorum longus tendon to reach the joint. The anterior tibial artery and the deep peroneal nerve must be identified and protected. Once the ankle is reached, the joint is roughly prepared and the cutting guides for the implants are inserted. The position is checked, and the size of the prosthesis is determined. There are several commercial prostheses designed for this approach, although we decided to use the Infinity™ Total Ankle System (Stryker Medical®) to minimize bias. After alignment examination, the implants are inserted, the planes are closed, and the wound is covered. The patient is placed in a cast for three weeks and starts weight-bearing in a boot after this period, using it for three more weeks.

The lateral approach utilizes an incision over the posterior aspect of the fibula. The lateral malleolus is osteotomized 1.5cm proximal to the joint and reflected distally to provide access to the articulation. An external frame is placed around the limb that supplies guidance for the prosthesis cuts. The sizing and position are determined and a Trabecular Metal Total Ankle™ (ZimmerBiomet®) is placed, the only available implant for the lateral approach. The fibula is reduced and fixed using a low profile anatomical lateral plate and screws. Planes are closed, the wound protected, and a cast placed. The post-operative carry is the same as the anterior approach.

Weight bearing CT (WBCT) scans will be used to evaluate outcomes. WBCT is the standard of care for the preoperative and postoperative assessment of patients undergoing total ankle replacement in our institution. Many secondary outcomes will be also evaluated through WBCT since they can better depict alignment, predict failure and diagnose complications (subsidence, cysts). No extra WBCT will be performed other than what we normally do for patients.

Randomization will be performed previously at the beginning of the study and will be performed by an outside researcher. Allocation will happen during surgery scheduling.