| Summary: | 碩士 === 中原大學 === 醫學工程研究所 === 91 === Proximal femoral osteotomy (PFO) has proven to be a successful surgical procedure in the correction of congenital femoral deformity. Traditionally, valgus corrective operation with subtrochanteric closed wedge osteotomy (Bombelli-osteotomy) of the proximal femur is commonly utilized in the treatment of patients with varus femur. Following the valgus osteotomy, a sliding hip screw and a four-hole side plate is used to stabilize the osteotomized femur. However, the drawbacks of the osteotomy complicating difficulty of later total hip arthroplasty due to the deformity of the proximal femur leading to inadequate prosthetic fixation, intraoperative femoral fracture and loosing. Based on our clinical experience, a new type of intertrochanteric valgus osteotomy (Z-osteotomy) was performed to correct coax vara and coax breva simultaneously. Theoretically, there are several advantages of this new type of osteotomy: (1) the post-op deformity is less than the Bombelli-osteotomy, (2) wedge resection is not needed, (3) bone graft is not necessary. Although the current clinical results were satisfactory, a thorough understanding of the biomechanical performance of this new type of osteotomy will be very informative and helpful for clinical practice. In the current study, a 3-D finite element analysis was thus aimed to investigate the differences of the biomechanical performance between the two different valgus osteotomies. By using the CT images obtained from a standardized composite femur, the solid model and hexahedral finite element mesh of the femora with preoperative femoral neck-shaft angles of 120°、110°、100° and 90° were created, respectively. Four FEM models with corrected 150° femoral-shaft angle for each type of osteotomy were then created. Loading simulating single leg stance was applied on each FEM model, and the material properties were assumed linear, isotropic and homogeneous. The stress distribution and the normal contact force of the four models were analyzed and compared. The results revealed that the stress distribution near the cutting plane and the normal contact force on the cutting plane for Z-osteotomy was lower as compared with those of the traditional Bombelli-osteotomy. Based on the results, we concluded that the Z-osteotomy might be an alternative for future clinical application.
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