A Closer Look At Total Ankle Replacement Revision
Although not definitive, researchers have recently determined a 10.2 percent (240 revisions/2,353 primary implants) incidence of revision, defined as component replacement, ankle or tibio-talo-calcaneal arthrodesis, or below-knee amputation.61,62 In a detailed systematic review, 78.6 percent of the revisions consisted of implant component replacement followed by arthrodesis (18.7 percent of revisions) and below-knee amputation (4.7 percent of revisions).63 Unfortunately, the outcomes of primary implantation of the most recent generation, the Agility LP Total Ankle Replacement System, and the ability to perform successful revision of a failed earlier-generation Agility Total Ankle Replacement System in general remain unanswered.
When A Distal Tibiofibular Syndesmosis Nonunion Occurs
Nonunion of the distal tibiofibular syndesmosis develops secondary to premature weightbearing, inadequate preparation of the syndesmosis for arthrodesis, metal fixation failure and the presence of unrecognized post-traumatic distal-lateral tibial necrosis. The surgeon should resect the nonunion until only healthy, viable bone remains. This frequently results in significant bone loss. While most publications recommend the use of impaction cancellous bone grafting supplemented with a fibular side plate and multiple fibula-pro-tibia compression screw stabilization, this approach mandates protracted periods of non-weightbearing, and union is often incomplete, making further revision likely.9,29,42,50,51,64
The subsequent revision is even more complex due to the multiple osseous defects in the fibula from prior hardware insertion and removal, and the need for resection of additional bone about the syndesmosis nonunion site resulting in significant osseous defects. Instead, we recommend the implantation of multiple 0.062-inch Kirschner wires bent and twisted into various geometric shapes (i.e., coils, crosses, pyramids, etc.) within the osseous defect followed by the insertion of polymethylmethacrylate cement, adhering to the principles of cemented total knee arthroplasty (see photos D-F on page 53).65,66
What You Should Know About Aseptic Osteolysis
The development of aseptic osteolysis following total ankle replacement is the major cause of failure. It increases with time and results in loss of fixation of the prosthesis. This process involves a macrophage mediated osteolytic destruction of periprosthetic bone secondary to phagocytosable UHMWPE wear debris usually as a result of component malposition.60,67-79 Specific to the Agility Total Ankle Replacement Systems, aseptic osteolysis about the tibial tray may or may not involve subsidence and/or component loosening. Aseptic osteolysis involving the talar component nearly universally involves varying degrees of subsidence and component loosening. The resultant bone loss can be quite extensive.37,80