Proximal Tibia Hemiarthroplasty Reconstruction Following Resection of Malignant Bone Tumors in Skeletally Immature Patients.

Background: Reconstruction of the proximal tibia following resection of malignant bone tumors in pediatric patients is traditionally limited to osteoarticular allografts or endoprostheses. Endoprostheses typically require resection or disruption of the distal femoral physis, which can lead to a leg length discrepancy (LLD). We introduce a novel form of proximal tibia limb reconstruction using a Compress® tibia hemiarthroplasty, which spares the distal femoral physis. Methods: We retrospectively reviewed 5 patients who underwent proximal tibia osteosarcoma resection and reconstruction with a custom Compress® proximal tibia hemiarthroplasty. Data on function, survival, LLD, complications, and patient-reported outcomes were collected. Results: Mean age at resection was 10.4 years [range: 8.8-12.9 years]. Mean implant survival was 59 months [range: 34-83 months]. One patient developed a deep infection, and two patients required implant lengthening. Both were later converted to a rotating hinged total knee arthroplasty (RHTKA) ​> ​58 months after index surgery. At the last follow-up, all living patients had knee range of motion from 0 to 110°, walked unassisted, and had no LLD or knee instability. Mean Toronto Extremity Salvage Score was 90 [range: 80-97]. Conclusions: Proximal tibia hemiarthroplasty reconstruction after tumor resection in skeletally immature patients preserves the distal femoral physis and may potentially reduce LLD and delay conversion to an RHTKA until after skeletal maturity. Key Concepts: (1)Osteosarcoma is the most common primary malignant bone tumor in children, arising most frequently around the knee.(2)Complete resection often requires excising the adjacent growth plate, creating a challenge for reconstruction in growing children to maintain function and avoid significant limb length inequality.(3)The custom expandable tibia hemiarthroplasty is a novel reconstruction option for skeletally immature patients requiring resection of the proximal tibia.(4)Although future research is needed, results of this study suggest that tibia hemiarthroplasty is a reasonable reconstruction option in growing children requiring oncologic resection of a primary bone tumor from the proximal tibia. Level of Evidence: Case series, Level IV.