Occult cement plug causing femoral canal obstruction during nailing after TKA: a case report.

With the aging global population, periprosthetic and post-arthroplasty femoral shaft fractures are becoming increasingly common. Although intramedullary nailing remains one of the classic surgical procedures for treating femoral shaft fractures in many cases, the presence of an unexpected space-occupying lesion within the medullary canal may often increase the surgical difficulty. This paper reports a case of a femoral fracture occurring 10 years after ipsilateral total knee arthroplasty in an 83-year-old female. On preoperative plain radiographs and CT, no clear intramedullary lesion was identified. However, during the subsequent fracture surgery, a dense polymethyl methacrylate (bone cement) plug was encountered that completely blocked reaming and nail insertion. The surgery was ultimately completed by using a side plate for fixation. This case indicates that radiolucent cement plugs retained from prior joint surgery may be missed on preoperative imaging. Orthopedic surgeons must therefore maintain a high index of suspicion and always have alternative fixation strategies available to manage such intraoperative crises effectively.