Fatigue fracture of the femur after navigated total knee replacement.

We present a case of fatigue fracture of the femur after navigated total knee arthroplasty with the Orthopilot system. A 60-year-old woman with rheumatoid arthritis and osteoporosis (T-score = -3.1) reported increasing pain of the thigh 8 weeks after the surgery. A fatigue fracture of the right femur through the pinholes was diagnosed and stabilized with an intramedullary nail, achieving union and a good functional result. To our knowledge, this is the first described fracture through the pinholes after Orthopilot-assisted surgery with 4.5 mm threaded pins for tracker fixation. We believe that the number of such complications is underestimated because reports are not published. Patients with osteoporosis should be informed about the possibility of this complicating fracture if they are undergoing navigated surgery.