Biomechanical Analysis of Fibular Graft Techniques for Nontraumatic Osteonecrosis of Femoral Head: A Finite Element Analysis

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background:</jats:bold> Free vascularized fibula graft (FVFG) technique has achieved the most consistent successful therapeutic effect on young patients diagnosed as nontraumatic osteonecrosis of femoral head (NONFH), of which the Core Track Technique (CTT) has been the most commonly used. As an alternative to CTT, the modified Light Bulb Technique (LBT) was reported to have a higher success rate. However, its biomechanical characters have been poorly understood. This study aimed to investigate the biomechanical properties of modified LBT in treating NONFH by comparing with CTT.<jats:bold>Methods: </jats:bold>Two types (C1 and C2) of NONFH finite element models were established from a healthy subject according to the Japanese Investigation Committee (JIC) classification, and CTT and LBT procedures were simulated in each type of the models. The average Von Mises stresses and stiffness of the proximal femur were calculated by applying 250% body weight loading on femoral head to simulate walking condition. In addition, two patient-specific models were built and simulated under the same boundary condition for the further validation of LBT.<jats:bold>Results:</jats:bold> In the healthy subject-derived models, both LBT and CTT resulted in reduced stresses in the weight-bearing area, central femoral head, femoral neck, and trochanteric and subtrochanteric regions, and increased structural stiffness after surgery. In the weight-bearing area, CTT reduced more stresses than LBT (36.19% <jats:italic>vs</jats:italic> 31.45%) for Type C1, while less reduction (23.63% <jats:italic>vs</jats:italic> 26.76%) for Type C2. In patient-specific models, stiffness and stresses of before and after surgery were also increased and reduced respectively, which is consistent with healthy subject-derived models.<jats:bold>Conclusion:</jats:bold> LBT and CTT have different biomechanical performance on different JIC type of NONFH. In terms of preventing the collapse of femoral head, LBT may be more effective for JIC Type C2, which could alternatively be chosen, while for JIC Type C1, CTT is still a better choice. Both techniques can improve biomechanical properties of NONFH with patients’ proximal femur stress reduced and structural stiffness enhanced.</jats:p>