摘要

脛骨骨折為人體中經常發生骨折之部位，脛骨前側有三分之一的面積只有皮膚包覆，在血液以及養份的供應上皆較差，骨折之復原較不容易。對此，LISS近端脛骨骨板提供了脛骨近端骨折微創的手術方式，且其將骨螺絲鎖固於骨板而固定骨螺絲角度之設計，適合於骨質較差之病人，臨床文獻上顯示LISS在近端脛骨骨折治療上有不錯的效果。但是實際臨床用此骨板治療脛骨骨幹近端骨折仍然有斷裂的案例發生，而文獻中對此類骨板之力學表現仍有不同之研究結果，因此對於此骨板用在治療近端脛骨骨折的生物力學情形，仍然值得探討。

本研究以有限元素模擬分析之方法，探討LISS近端脛骨骨板固定於不同部位及不同型態之近端脛骨骨折的生物力學表現，及不同骨螺絲位置對於受力的影響。並以各種材料測試試驗，對臨床上使用後實際斷裂之骨板進行分析，再與有限元素模擬之結果進行對照。

有限元素模擬之結果顯示，脛骨骨折部位越靠近於脛骨遠端時，骨板之受力會越來越大；骨板用於固定斜向脛骨骨折之受力會比用於固定橫向骨折為高；改變骨螺絲之位置以增長骨板的工作長度，可降低骨板之受力。此外在鎖上骨螺絲的孔洞周圍易產生應力集中的現象，此現象容易產生疲勞裂縫，對照材料測試結果以及臨床之情形，此應力集中之作用即造成骨板疲勞破壞而產生之原因。因此在臨床使用上，若病人骨折復原情況緩慢，則必須注意骨板發生疲勞斷裂之情況。

對此骨板之改進，本研究建議可由兩個方向來改善，在骨板之近端外形，設計符合國人骨骼之外型，可減少骨板的彎曲程度，降低骨板近端之應力集中，同時改進骨板製程，增加骨板之疲勞強度，減少疲勞斷裂的機率。

Abstract

Tibial fractures are the third most common fracture type following femur and radius/ulna fractures. The tibia has one third area, which is only covered by skin and lack of blood and nutrient supply with poor bone healing. The Less Invasive Stabilization System (LISS) for proximal tibial fractures provides a locking mechanism of the screw in the plate which offers angular stability and is suitable for patients with osteopenia or osteoporosis. LISS proximal tibia plate has been clinically efficacy on the fixation of proximal tibial fractures for bone healing. However, the biomechanics of the fixation of LISS on tibital fractures are still not clear. The purpose of this research was to apply finite element method to characterize the biomechanical performance of the proximal tibia plate to stabilize the proximal tibia fracture.

Finite element method was used to analyze the stresses distribution on the fixation of the plate to three different sites of, two common types of proximal tibial fractures and different screw positions. In addition, a fractured plate after clinical use was investigated by using material testing to determine fracture characteristics and to validate through the outcomes of finite element analysis.

The analytical results illustrate that (1) the higher stress are occurring in the plate, while the tibia fracture site is more closer to the distal region of tibia; (2) the fixation of oblique fracture has led to higher stress in the plate than the fixation of transverse fracture; (3) a change of screw position to increase the working length of plate is led to the reduction of stress in the plate. In all conditions, the stress concentration are occurred around the screw hole of the plate, which may lead to fatigue failure of the bone plate. This may also lead to the delay of fracture healing.

The results of this research have suggested the following two designs to the improved bone plate: (1) smooth the curvature in the proximal region of the plate to fit the bone contour of domestic people and to reduce the stress; (2) improve the manufacture process to enhance fatigue strength of the plate.

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