股骨轉子間Z型外翻截骨術 之三維有限元素分析

Three-Dimensional Finite Element Analysis of the Z-type Intertrochanteric Valgus Osteotomy

梁蘭麗(Lan-Li Liang)

指導教授 ： 李炫昇 ； 陳文斌

中原大學/工學院/醫學工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300741

摘要

股骨近端截骨術在矯形外科手術上，已成功應用於治療先天或後天性股骨形變的病患。針對股骨頸內翻的病例，傳統上的治療方式，是以轉子下外翻截骨術於股骨近端施以封閉楔形切除後，進行股骨頸之外翻矯正，最後再以股骨固定裝置予以鎖固。但是術後過大的股骨變形，往往導致日後於進行全人工髖關節置換手術時，產生人工關節無法有效定位、手術中骨折及術後鬆脫等諸多風險。近年來，長庚醫院骨科已利用Z型轉子間外翻截骨術成功施行多例之股骨頸外翻手術，術後證實臨床效果良好。相較於轉子下封閉楔形外翻截骨術，此一Z型轉子間外翻截骨術具有以下諸多優點：(1)術後股骨變形較不明顯；(2)無需進行楔形切除，因此無自體骨骼損失；(3) 無需補骨。現階段Z型截骨術術後臨床結果雖然令人滿意，但是仍無相關文獻以生物力學的觀點，針對此一改良型截骨術進行力學評估。為此，本研究的主要目的，是利用有限元素分析方法探討二種不同外翻截骨術術後之力學差異性。首先利用標準人造股骨之電腦斷層(CT)掃描影像，產生術前股骨頸夾角分別為120°、110°、100°和90°等四組股骨實體模型與六面體有限元素網格，再經轉子下封閉楔形外翻截骨術及Z型轉子間外翻截骨術，使股骨頸夾角矯正為150°。將模型給予單腳站立的邊界條件，材料設定為線性、均質，截骨界面設定為接觸型態給予摩擦係數，並針對應力以及正向於截骨面的接觸力分佈進行分析討論。結果顯示，四組術前不同股骨頸夾角之股骨，經Z型轉子間外翻截骨術矯治後，其截面之應力及正向力較低，較具臨床優勢。

關鍵字

有限元素分析 ； 股骨內翻 ； 轉子間外翻截骨術 ； 股骨近端截骨術 ； 轉子下外翻截骨術

並列摘要

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.

並列關鍵字

Proximal femoral osteotomy ； Coxa vara ； Subtrochanteric valgus Osteotomy ； Finite element analysis ； Intertrochanteric valgus osteotomy

參考文獻

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