The Use of a Modified Total Knee Arthroplasty to Treat End-Stage Osteoarthritis and Concurrent Osseous Metastasis to the Distal Femoral Metaphysis

Background: In recent years, improved survivorship in cancer patients is paralleled by increasing demand for total knee arthroplasty (TKA) procedures. Thus, there is a need to explore different approaches to patients requiring a TKA with comorbid metastatic disease of the distal femur. We herein present a patient who underwent a modified primary TKA for end-stage osteoarthritis and concurrent skeletal metastasis to the distal femur. Case Information: An 84-year-old woman presented to our clinic for severe osteoarthritis. Imaging revealed an osteoblastic lesion in the distal femoral metaphysis, and MRI identified it to be a metastasis of an undisclosed diagnosis of renal cell carcinoma. She underwent a modified TKA with a 175-mm femoral stem with resection of the bony metastasis. The postoperative course was unremarkable. Conclusions: We believe patients with distal femoral metastases and end-stage osteoarthritis should be considered candidates for a modified TKA. It offers immediate weight-bearing, tumor resection, pathologic fracture prevention, and is fiscally favorable to the alternative, a limb salvage procedure with endoprosthesis. The femoral stem component allowed for immediate stability, decreased risk for aseptic loosening, and protection of the canal from further development of metastases. This is the first report discussing the utilization of a modified TKA in treating end-stage osteoarthritis with simultaneous resection of bony metastases from renal cell carcinoma and prophylactic pathologic fracture management. Improvements in cancer survivorship requires orthopedic surgeons to consider modified interventions for patients with osteoarthritis and comorbid metastatic disease of the distal femur.