Bilateral Extensor Mechanism Disruption After Total Knee Arthroplasty in Two Morbidly Obese Patients

Disruption of the extensor mechanism as a result of patellar tendon or quadriceps tendon rupture is an uncommon but devastating complication after total knee arthroplasty. Treating a disrupted extensor mechanism can be challenging, particularly in patients who are morbidly obese, due to an increased risk of postoperative complications. Therefore, despite the debilitating nature of extensor mechanism disruption, many community surgeons do not feel comfortable pursuing more complex cases like revision total knee arthroplasty with extensor mechanism allograft on morbidly obese patients, and consequently many of these patients are referred to tertiary-care centers for reconstruction secondary to the complexity of this patient cohort. The authors report 2 cases of bilateral extensor mechanism disruption after total knee arthroplasty in patients who are morbidly obese. One patient experienced trauma leading to her initial rupture; however, her contralateral atraumatic disruption was subsequently diagnosed at a later date. The second patient did not experience trauma leading to either of her extensor mechanism disruptions. Despite substantial medical comorbidities and morbid obesity, revision total knee arthroplasties with extensor mechanism allografts were recommended in both cases in a staged bilateral fashion. The surgical technique is described and the unique challenges afforded by the marked obesity are detailed. The current literature on this subject is reviewed. Despite early complications related to recumbency, this report serves as an example of successful repairs of extensor mechanism disruptions in patients who are morbidly obese, suggesting that extensor mechanism allograft is viable even in patients with high risk of complications.