Concomitant bone regeneration to restore bone stock during revision distal femur replacement after large tumor resection

Abstract

Loss of bone stock is a common problem in revision arthroplasty, specifically in large distal femur replacements (DFRs) after tumor resection. It can lead to worse functional outcomes and increased risk of revision procedures. Restoration of bone using distraction osteogenesis (DO) with an intramedullary nail may be an appropriate solution for this problem, especially in younger adults who may require future surgical interventions. In this series of three patients, we describe the successful use of DO through an internal device to address bone loss after a large osseous resection and revision endoprosthetic reconstruction. Bone stock was restored with a combination of lengthening and bone transport using a multistage revision strategy: removal of existing hardware, treatment of infection if present, lengthening of proximal femur with a temporary antibiotic spacer in the distal femur, and reimplantation of a definitive DFR after bone stock restoration. A magnetically actuated internal lengthening intramedullary rod was utilized to perform the proximal femur osteoplasty. Conversion to a definitive weight-bearing DFR was achieved in two patients; one patient required an above-the-knee amputation for chronic osteomyelitis which could not be controlled after numerous debridements and courses of IV antibiotics. In this patient, the infection could be eradicated from the lengthened bone, the regenerate bone served to provide length to the amputation stump and fully remodeled to provide full weight-bearing and prosthetic use. DO was successfully used in three patients for revision DFR and bone stock restoration. In one of the two patients who required revision surgery for infection, amputation was ultimately required. All three patients achieved successful bone regeneration.