股骨近端截骨術固定裝置之生物力學分析

Biomechanical Study on the Fixation Devices of Proximal Femoral Osteotomy

柳孟鏘(Menq-Chiang Leou)

指導教授 ： 陳文斌

中原大學/工學院/醫學工程研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100347

摘要

治療缺血性骨骨頭壞死，股骨近端截骨術是全人工髖關節置換手術之外的另一種選擇。股骨近端截骨術的概念，是藉由轉骨手術將承重部位的壞死區域轉移到非承重區。本研究目的，是以有限元素法來分析股骨近端截骨術中DHS固定裝置及四支骨螺釘固定裝置，及探討四種不同截骨位置，所造成的術前術後之應力分佈的影響。希望由此研究，從生物力學的觀點，可以提供醫師手術時選擇截骨平面時有一個依據，藉此可以得到較佳的手術結果。
我們採用人造股骨的CT影像來建立完整的股骨三維有限元素模型，基於完整股骨模型，我們建立了DHS固裝置和四支骨螺釘固定裝置以及四種不同截平面的模型。DHS固定裝置四組截骨模型分別定義為DHS-1(正常截骨位置)、DHS-2(下移0.5公分)、DHS-3(下移1公分)、DHS-4(下移1.5公分)，同樣地，四支骨螺釘固定裝置四組截骨模型分別定義為4S-1(正常截骨位置)、4S-2(下移0.5公分)、4S-3(下移1公分)、4S-4(下移1.5公分)。我們得到了應力分布的趨勢及術前與術後勁度的改變。
當截平面由DHS-2移到DHS-3時，有明顯的應力集中現象，由4S-2移到4S-3時亦同。各組模型的勁度如下，Intact: 3086 N/mm、DHS-1: 2989 N/mm、DHS-2: 2753 N/mm、DHS-3: 2113 N/mm、DHS-4: 1165 N/mm、4S-1: 2371N/mm、4S-2: 2147N/mm、4S-3: 1726N/mm、4S-4: 568N/mm。勁度愈高代表術後股骨的穩定性愈高。
有限元素結果指出，建議截骨位置從正常位置往下平移不得超過0.5公分，否則易導致早期的破壞。DHS固定裝置的表現比四支骨螺釘固定裝置要好。DHS-1的勁度與完整股骨最接近。手術時建議以DHS-1來施行，因其最為穩定。

關鍵字

固定裝置 ； 動態股骨螺釘 ； 有限元素分析 ； 缺血性股骨頭壞死 ； 股骨近端截骨術

並列摘要

Proximal femoral osteotomy (PFO) is an alternative solution besides total hip arthroplasty (THA) for relatively younger avascular necrosis (AVN) patients. The concept of the PFO is to move the weight-bearing necrotic area to a non-weight-bearing region by rotational osteotomy. The objective of this study is to investigate the effects of four different PFO levels on the stress distributions of bone and fixation devices using finite element analysis, and to compare the biomechanical properties using either multiple screws or dynamic hip screw fixation. It is hoped that through this research a guideline for the osteotomy level for the PFO` can be provided to surgeons and a better outcome can be obtained from a biomechanical point of view.
CT image data of a standardized composite femur was used to create a 3-D finite element intact femur model. Based on the intact model, four models simulating four different levels of osteotomy line together with the implanted DHS fixation system and multiple screws fixation system were created . The four models of different osteotomy levels for the DHS fixation system were defined as DHS-1 (normal transtrochanteric line), DHS-2 (0.5cm distal), DHS-3 (1cm distal) and DHS-4 (1.5 cm distal) of DHS fixation system. As for the multiple screws fixation system, the four models of different osteotomy levels were defined as 4S-1 (normal transtrochanteric line), 4S-2 (0.5cm distal), 4S-3 (1cm distal) and 4S-4 (1.5 cm distal). The stress distributions were found and the pre- and post-operative stiffness values of the femur-implant complexes were found.
There was a significant stress rise when the osteotomy line moves from DHS-2 to DHS-3, or from 4S-2 to 4S-3. The stiffness value for each model was calculated respectively (Intact: 3086 N/mm, DHS-1: 2989 N/mm, DHS-2: 2753 N/mm, DHS-3: 2113 N/mm, DHS-4: 1165 N/mm, 4S-1: 2371N/mm, 4S-2: 2147N/mm, 4S-3: 1726N/mm, 4S-4: 568N/mm). Higher stiffness value represents higer stability for the femur-implant complex.
According to the finite element results, the osteotomy line should be carefully designed and limited to no more than 0.5 cm distal to the intertrochanteric line. The performance of DHS fixation device is better than that of multiple screws fixation system. The DHS-1 model has a stiffness value closer to that of the intact femur than other models. Therefore, DHS-1 is suggested from the stability consideration.

並列關鍵字

Femoral head avascul ； Proximal femoral osteotomy

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