Effect of Sclerosis Bands in Femoral Head Necrosis on Non-Vascularized Fibular Grafting-A Finite Element Study.

Objective: Femoral head necrosis is a challenging condition in orthopaedics, and the occurrence of collapse is an important factor affecting the prognosis of femoral head necrosis. Sclerosis bands are known to influence the collapse of the femoral head, yet there is a lack of research on the biomechanical role of sclerosis bands in non-vascularized fibular grafting surgery. This study aims to evaluate the biomechanical impact of sclerosis bands in femoral head necrosis and their role in non-vascularized fibular grafting surgery (NVFG) using finite element analysis.

Methods: We constructed 11 finite element models based on CT scan data of a normal hip joint, simulating different sclerosis band thicknesses and defect scenarios. The models were analyzed for changes in femoral head displacement and von Mises stress. We constructed a hip joint model based on CT data from a normal hip joint, and after reconstruction, assembly, and optimization using 3-matic. We created five groups consisting of 11 finite element analysis models of the hip joint. Mesh partitioning and mechanical parameter settings were performed in ANSYS. The changes and differences in femoral head displacement and von Mises stress of these models were analyzed.

Results: Increasing sclerosis band thickness led to reduced peak displacement of the femoral head by 28.6%, 42.9%, and 47.6%, and increased surface von Mises stress by 28.3%, 13.8%, and 13.0%, respectively. Post-surgery, peak displacement decreased in all groups compared to pre-surgery levels. Increasing sclerosis band thickness post-surgery resulted in decreased maximum von Mises stress of the femoral head by 13.9%, 3.0%, and 8.1%. Defect volume in the defect groups correlated with increased peak displacement of the femoral head by 10.0%, 30.0%, and 100.0%, and increased surface maximum von Mises stress of the femoral head by 9.3%, 14.0%, and 15.1%.

Conclusion: Sclerosis band formation exacerbates von Mises stress concentration on the femoral head surface. However, thicker sclerosis bands improve post-NVFG stability and mechanical performance. Larger anterior lateral sclerosis band defects significantly compromise postoperative stability, increasing the risk of collapse. Protecting the anterior lateral sclerosis band during NVFG surgery is crucial.