The complications involving knee extensor mechanism are seen in 1% to 12% of patients after total knee arthroplasty, and have significant negative effects on patient outcomes and satisfaction. This review focuses on three of the most common problems: patellar tendon disruption, quadriceps tendon rupture, periprosthetic patellar fracture. The purpose of this report is to review the relevant anatomy of the knee extensor mechanism, present the current risk factors that may lead to extensor mechanism complications, provide diagnosis algorithms and treatment options. Although various surgical techniques have been developed, it is difficult to effectively manage the extensor mechanisms and patient expectations in complications after total knee arthroplasty.