Comparison of Fragment Removal Versus Internal Fixation for Treatment of Pipkin I Femoral Head Fractures: A Finite Element Analysis

Fragment removal and internal fixation are the principle treatments for Pipkin type I femoral head fractures. The aim of this study was to compare, using a finite-element method, changes in stress on the femoral head after 2 different operation types. A three-dimensional (3D) finite-element model of a Pipkin type I femoral head fracture was generated with MIMICS and ABAQUS software. A 3D numerical screw model was reconstructed based on data from BIOFIX and using SOLIDWORKS software. The screw was implanted in the fragment and femoral head to reconstruct the implantation. Stress changes on the femoral head after removal of the fragment and internal fixation were investigated. Mean stresses along 13 points were 16.94 +/- 16.79 MPa in the fragment removal group and 14.17 +/- 14.08 MPa in the internal fixation group (P < 0.05). Random tests indicated that the mean stresses along 50 randomly determined points were 25.41 +/- 12.12 MPa in the fragment removal group and 19.45 +/- 14.62 MPa in the internal fixation group (P < 0.05). Compared with internal fixation, fragment removal led to greater stress that was more concentrated in the femoral head.