Outcomes of Megaprosthesis Reconstruction for the Salvage of Failed Osteoarticular Allograft Around the Knee implanted before Skeletal Maturity in Primary Bone Sarcoma: A Case-Series

Objectives: Functional expectations following the salvage of a failed osteoarticular allograft are poorly described. In this study, we aim to evaluate functional outcomes, implant survival, and complications of the megaprosthesis in salvaging a failed osteoarticular allograft around the knee.Methods: We retrospectively reviewed the medical profiles of ۲۱ skeletally mature patients who underwent megaprosthesis reconstruction to salvage a failed osteoarticular allograft around the knee implanted before skeletal maturity. The location of reconstruction was the proximal tibia in ۱۳ patients and the distal femur in eight patients. Knee function was evaluated by the Musculoskeletal Tumor Society (MSTS) score and the Toronto Extremity Salvage Score (TESS).Results: The mean age of patients was ۱۶±۱.۷ years. The mean interval between the primary (allograft) and secondary (megaprosthesis) reconstructions was ۵۹.۴±۲۳.۶ months. At an average follow-up of ۵۱.۲ months, the mean knee range of motion was ۱۰۱.۲±۱۵.۶°. The mean MSTS score and TESS were ۸۳.۶±۷ and ۸۶.۶±۷.۹, respectively. The mean limb length discrepancy was ۲.۵±۱ cm before and ۰.۳۶±۰.۷۴ cm after the operation (P<۰.۰۰۱). Six postoperative complications (۲۸.۶%) occurred in this series, including one wound dehiscence, one periprosthetic fracture, two acute infections, one aseptic loosening, and one delayed periprosthetic infection. Only the last two complications required revision. Accordingly, the two- and five-year implant survivals were ۹۵.۷% and ۹۰%, respectively.Conclusion: Megaprosthesis is a viable option for salvaging failed osteoarticular allografts around the knee. It also provides the opportunity to correct the limb length discrepancy. Level of evidence: IV

Keywords:

Bone tumor , knee , oncologic prosthesis , Osteoarticular Allograft , salvage