Component Fracture in the Kotz Modular Femoral Tibial Reconstruction System: An Under-Reported Complication

摘要

Abstract Background Primary bone tumors of the femur are commonly reconstructed using an endoprosthesis. Different modes of implant failure have been described, including structural failure; although uncommon, this may be an under-reported complication. The purpose of this study is to examine the rates and risk factors for implant fracture of the Kotz Modular Femoral Tibial Reconstruction system (KMFTR). Methods Two hundred twenty-one patients (95 women and 126 men) who underwent a KMFTR reconstruction were reviewed. Twenty-seven patients (12%) sustained a prosthetic fracture. The mean time to fracture was 7 years postoperatively. The fractured component most commonly involved the distal femur (n?= 21) and a screw hole in the stem (n?= 12). In patients with stem fractures (n?= 21), the mean intramedullary stem diameter was 12 mm and the mean extramedullary component length was 18 cm. Results Compared to patients who did not fracture, those with a prosthetic fracture had a significantly smaller stem diameter (12 vs 14 mm, P ?= .001) and a significantly longer extramedullary component length (18 vs 15 cm, P ?= .04). There was no difference between the preoperative and postoperative Toronto Extremity Salvage Scores ( P ?= .98), Musculoskeletal Tumor Society 87 ( P ?= .78), or Musculoskeletal Tumor Society 93 ( P ?= 1.0) ratings for patients with or without a prosthetic fracture. Conclusion This study shows that fracture is an under-reported complication associated with the KMFTR stem. We identified an endoprosthetic component fracture rate of 12%. Patients with smaller stem diameter and longer resection lengths were more likely to sustain a stem fracture. Subsequent revision provides a durable means of reconstruction, with no significant loss of patient function.