A Biomechanical Analysis of Surgical Procedures for Osteonecrosis of the Femoral Head using Three-Dimensional Finite Element Method: A Parametrical Analysis by Varying Physiological Loading Conditions / 대한정형외과연구학회지

ABSTRACT

Many operative procedures for osteonecrosis of the femoral head(ONFH) have been proposed, but their clinical results remain controversial to many clinicians. Recently, a new surgical procedure that incorporates cementation with polymethylmethacrylate(PMMA) after core drilling has been tried clinically. In this study, a finite element method (FEM) was employed to analyze and compare various surgical procedures of ONFH to provide a biomechanical insight by varying physiological loading conditions. Our finite element models were constructed for this purpose they included normal, necrotic, core decompressed, fibular bone grafted, and cementation models. The extent of necrotic region was determined based upon the average CT-scan data from 10 patients. The physiological load directions and magnitudes during the gait cycle were selected at the stage of heel-strike, toe-off, and average stance. The von Mises stresses were calculated and volumetric percentages of the necrotic region under different levels of stresses were analyzed for each model. Our results indicated that there were substantial increase of the necrotic region subjected to the high stress level (beyond 11 MPa) and decrease in the low stress level (below 5 MPa) with the core decompression model, an indication of a malignant stress transfer pattern. On the other hand, the exact opposite pattern of stress transfer was noted with the fibular bone graft and cementation methods suggesting that they could provide structural integrity within the necrotic region.