Extensor mechanism complications after total knee arthroplasty are relatively uncommon but potentially devastating. The etiology of these complications, which includes patellofemoral instability, periprosthetic patellar fracture, and disruptions of the quadriceps tendon and patellar ligament, has become better defined in recent years, with a subsequent decrease in the incidence, primarily resulting from changes in surgical technique and component design. In addition to addressing the patient's specific failure mechanism, the treatment of extensor mechanism complications after total knee arthroplasty may include nonsurgical management, primary repair, or reconstruction with autogenous, allogeneic, or synthetic tissue. Prevention of these complications, the foremost goal, is achieved through identification of patient and procedure risk factors, meticulous surgical technique, including vigilance during exposure and retractor placement, and a high index of suspicion both during and after the procedure.