Post-Traumatic Periprosthetic Tibial and Fibular Fracture After Total Ankle Arthroplasty: A Case Report

Partial revision of a dislocated periprosthetic tibial fracture after total ankle replacement with a stemmed implant and plate fixation: A case report

INTRODUCTION

Total ankle arthroplasty (TAR) procedures have become more reliable and incidence is increasing. A growing number of postoperative complications can be expected and should be correctly addressed.

PRESENTATION OF CASE

A 43-year-old woman suffering from severe ankle osteoarthritis underwent TAR (Stryker's Infinity with Prophecy alignment guides, uncemented tibial component and cemented talus component). After a fall, one month after the surgery, she presented with a fracture of the medial malleolus and an anterior periprosthetic fracture of the tibia, with anterior dislocation of the tibial prosthetic component. Fracture fixation and partial revision surgery was planned using the same anterior surgical access. To restore length, rotation and joint articulation, the medial malleolus was first reduced and synthesized with a plate and 6 screws through additional minimally invasive medial ankle incisions. Once the medial malleolus was stabilized, the already mobilized tibial component was removed. Freehand cuts under fluoroscopic guidance on the anterior surface of the tibia were performed. After a final check with a trial component, a Stryker's Inbone II stem, which matched the previously inserted talar component, was implanted and partially cemented to fill the remaining bone gaps.

DISCUSSION

Only few case reports of periprosthetic ankle fractures exist, and none of them were similar to ours. There are no published precedents for this revision approach from a stemless to a stemmed tibial implant without changing the talar implant.

CONCLUSION

Partial revision after a complex periprosthetic fracture results in a satisfactory outcome if surgery is performed in specialized centers.

In Silico Analysis of Bone Tension During Fixation of the Medial Malleolus Fracture After Ankle Joint Endoprosthesis

Total ankle arthroplasty (TAR) is a procedure alternative to arthrodesis which enables the biomechanical stabilization of the ankle joint. The procedure is associated with a high risk of complications, including fractures of the medial malleolus. In this study, the finite element method (FEM), based on CT examinations, was used to model the ankle fracture fixation after TAR. Three types of fracture stabilization were considered: screw, Blount staple, and both screw and Blount staple. In the in silico model, the maximum stress tension was found at prosthetic junctions with the base, cone, and talar components of the tibial prosthesis. When the fracture was stabilized with the Blount staple, tension along the cone of the tibial component was about 12% of the maximum tension. Stabilizations with the screw alone or Blount staple combined with a screw on the medial side of the cone induced tension in the immediate vicinity twice as high. In the area of the medial malleolus, the tension was alike for both types of stabilization. The tension was lowest when using the Blount staple alone. We conclude that, contrary to the hitherto clinical routine of using screws, fracture fixation using the Blount staple leads to the lowest bone tension around the fixation of the medial malleolus fracture after ankle joint endoprosthesis.