Case: A 51-year-old male construction worker with a history of chronic quadriceps tendon rupture presented with no active knee extension and tricompartmental knee osteoarthritis. He underwent simultaneous total knee arthroplasty and extensor mechanism allograft reconstruction. At 4 years postoperatively, the patient had pain-free knee function and active extension.
Conclusion: The combination of a chronic quadriceps tendon rupture with lack of active knee extension and knee osteoarthritis is a rare and challenging problem. To our knowledge, this combined diagnosis and the treatment described in this case report have not been reported previously in the literature.