Abstract
Category:
Ankle Arthritis
Introduction/Purpose:
The consequence of a missed syndesmotic insufficiency during mobile bearing total ankle replacement (TAR) surgery is subsequent valgus deformity leading to dissociation of the distal tibiofibular joint and failure of the TAR. The purpose of this study was to retrospectively review the patients who developed a syndesmotic insufficiency, which lead to a revision surgery, after primary TAR in our centre. The primary goal was to identify red-flags for possible syndesmotic insufficiency in preoperative planning of TAR, in order to reduce this type of complication.
Methods:
We identified twenty patients (12 females and 8 males) with a missed instability of the distal tibio-fibular joint appearing 3.5 years (range 0.8-9.5 years) after primary TAR. Patient’s records, preoperative and postoperative radiographs and intraoperative fluoroscope images were reviewed especially with regard to previous ankle or lower leg fractures. Functional outcome was assessed with the use of the American Orthopaedic Foot&Ankle (AOFAS) hindfoot score.
Results:
The mean follow-up after last revision surgery was 3.5 years. The median AOFAS Score at last follow-up was 72.5. We could identify 3 risk factors for possible failure:
(a) The nature of trauma: Weber-C-Type fractures or Maisonneuve-Type fractures were found in 13 of 20 cases. (b) A defect in the lateral tibial plafond after for example, a pilon fracture or arising due to cyst formation, was found in 3 cases. Here we concluded that the defect lead to a subsequent valgus tilt of the tibial component, acting as a stress riser in the distal tibio-fibular joint. (c) The remaining 4 cases showed a high tibial resection probably leading to an iatrogenic lesion of the anterior and posterior distal tibio-fibular ligaments.
Conclusion:
Knowing the etiology of posttraumatic osteoarthritis of the ankle joint is mandatory to identify a syndesmotic insufficiency in the preoperative work-up for mobile bearing three-component TAR. Due to these findings, our surgical protocol for TAR was adapted accordingly. If one or more of the risk factors are present during surgery we suggest performing distal tibio- fibular fusion.