Periprosthetic ankle fractures. Classification and treatment algorithm

Background. Total ankle replacement (TAR) has gained more and more interest in the last decade and has become a reasonable treatment option for symptomatic ankle arthritis. Due to increasing number of TARs and a prolonged survival rate, periprosthetic fractures occur as a complication, which is already known from total hip and knee replacement. Objectives. The aim of this study was to develop a classification of periprosthetic ankle fractures, which can guide the surgeon's decision-making in treating these rare fractures. Methods. All TARs (including prosthesis replacement) were retrospectively collated and analyzed with respect to periprosthetic fractures. All fractures were classified according to the point in time (e.g. intraoperative or postoperative fracture), localization (e.g. tibia, fibula or talus), fracture morphology and prosthesis stability. Results. Retrospectively 21 patients (4.2%) with periprosthetic fractures were identified. Of the patients 11 had an intraoperative fracture (type 1 fractures) and the remaining 10 fractures were postoperative fractures, which in turn were traumatic (type 2 fractures) in 2 and postoperative fatigue (type 3) fractures in 8 patients. Conclusion. Periprosthetic ankle fractures are a very rare complication. Nevertheless, a differentiated treatment algorithm is necessary depending on the cause of the fracture, localization and prosthesis stability. Based on more than 500 TARs this study offers for the first time a classification system for periprosthetic fractures following TAR. By systemically categorizing the different types of periprosthetic fracture this classification assists in therapeutic decision-making as it allows a differential causal analysis and guides indicated surgical or conservative treatment concepts.