Purpose: To overview the complications involving extensor apparatus of the knee following total knee arthroplasty (TKA) and to summarize which are the lines of treatment available and their reported outcomes in literature.
Methods: A comprehensive search of several databases was performed using as basic keywords "complications after TKA", "extensor mechanism disruption", "periprosthetic patellar fracture", "quadriceps tendon rupture", "quadriceps tendon rupture" isolated or combined with other terms by using Boolean operators. The methodological quality of each article was also evaluated using the Coleman methodology score (CMS).
Results: Twenty-nine studies were evaluated. The mean CMS of the studies selected was 33.1/100. Patellar fractures, requiring surgical treatment when there is rupture of the extensor mechanism or loosening of the patellar component, were treated surgically in 28.1 % of patients. The patellar and quadriceps tendon ruptures were surgically treated with reconstruction or augmented repair, respectively, in 98.6 and 76.5 %.
Conclusion: Complications involving the extensor apparatus of the knee following a TKA need early and appropriate management to avoid their devastating influence on joint functionality. Management has to be evaluated very carefully based on the site of the lesion, integrity of the prosthetic components and surrounding tissue to restore, and the patients' individual characteristics. The surgical approach for comminuted periprosthetic fractures and reconstruction of torn tendons of the extensor apparatus are needed to restore function and decrease pain, but, given the poor methodological quality of the studies published so far, it is not clear which surgical technique or graft leads to better outcomes. Therefore, there is an absolute need for better designed comparative trials producing clearer and stronger evidence on this critical matter.
Level of evidence: IV.
Keywords: Extensor mechanism; Periprosthetic fractures; Post-operative complications; TKA; Tendon tear.