Intercalary Allograft Reconstruction of the Femur: A Cadaveric Comparison of Intramedullary and Plate Fixation Techniques

Intercalary reconstruction following diaphyseal tumor resection is advantageous in that they preserve the joint above and below. Recently, intramedullary devices such as intramedullary nails (IMN), photodynamic bone stabilizing system (PBSS), and intercalary endoprosthetic reconstruction (EPR) have become increasingly used. Understanding the tradeoffs associated with each construct as well as characterizing their mechanical stability is essential for making a patient-specific decision for reconstruction. The mechanical properties of four different constructs used in the reconstruction of segmental defects in a femur model were compared: Double plate (DP) allograft secured by 90-90 plating, allograft secured by IMN and plate fixation, allograft secured by PBSS and plate fixation, as well as an intercalary prosthesis (EPR). Samples were tested in axial, bending and torsional loading, and mechanical properties were compared. The EPR during anterior-posterior bending had 51.63% of the displacement compared to the DP (p = 0.0007), and 55% of the creep over 100 cycles (p = 0.0126) with a rigidity of 201.3% (p = 0.0067). This difference also exists for cyclic torsion where the EPR rotates 52.32% the amount of the DP (p = 0.0044) and has 4.44% of the creep (p < 0.0001). The PBSS and IMN constructs had comparable results across all tests (p > 0.05). Overall, the EPR has comparable or superior mechanical stability to the DP, while the PBSS and IMN have similar mechanical properties. Together, these results can be used as a guide for surgeons to choose different implants depending on individual patient needs.