Acute Extensor Mechanism Disruption Following Total Knee Arthroplasty: Biologic Augmentation of Direct Repair Utilizing a Semitendinosus and Gracilis Autograft

Background Extensor mechanism disruption (EMD) is a devastating complication following total knee arthroplasty (TKA). Treatment options vary depending on the chronicity of the injury and integrity of the remaining tissue, with allograft and synthetic mesh reconstruction representing the most common surgical modalities utilized. In this study, we present the surgical technique and clinical outcomes of primary extensor mechanism repair with biologic augmentation utilizing a gracilis and semitendinosus autograft in the setting of acute EMD. Methods Institutional Review Board-approved data from our institutional registry spanning from 2013 to 2024 was queried for TKA patients who underwent an acute extensor mechanism repair. The described technique involves open reduction, internal fixation if a patella fracture is present, or direct repair of patellar tendon ruptures with augmentation utilizing a gracilis and semitendinosus autograft tunneled through the tibia, looped over the patella, and sutured into place. Results Seven primary TKA patients with acute EMD underwent the described technique. Six out of seven patients had an intact repair at final follow-up, with active extension present. One of these six had a small residual extensor lag of 3°. One patient developed a recurrent EMD in the setting of prosthetic joint infection, necessitating placement of a static spacer and was ultimately lost to follow-up. Conclusions Primary repair with biologic augmentation utilizing a gracilis and semitendinosus autograft is a viable method to restore extensor mechanism function in acute disruptions following TKA. This technique demonstrated successful maintenance of active extension without the need for synthetic mesh or allograft tissue.