開發歷史超過一百年的人工髖關節，是目前所有人工關節手術中有較好之成功率的手術之一。在臨床觀察中發現，人工髖關節仍有下列兩項不良的問題：經磨耗產生之碎屑侵入骨髓腔而造成骨溶解；股骨因植入物之應力遮蔽所導致之骨鬆現象。另外針對僅股骨頭局部軟骨退化或骨質壞死的病人，卻需進行切除股骨頭及骨頸的置換手術，不僅手術時間長且骨本流失多，另外也使得未來可能的二次手術成功率降低。本論文將進行有限元素分析，探討各類型植入物之設計及材質對股骨及植入物之應力的影響，期望能更進一步了解有柄、無柄及表面置換植入物設計及材質對股骨近端的影響。
在有限元素分析中，由電腦斷層掃描取得股骨剖面資料，再使用Amira軟體建立股骨三維實體模型，另外以SolidWorks軟體繪製相關人工髖關節植入物。將各式植入物依手術之方式植入股骨，施加身體負載及肌肉力於股骨，並固定股骨遠端，以模擬正常人單腳站立之情形。針對四種植入物材料性質（鈦合金、鈷鉻鉬合金、未強化及強化之PEEK）與各類型植入物（有柄式、無柄式及表面置換型）之不同外形設計，進行有限元素分析。從股骨von Mises應力及植入物最大主應力去探討植入物之設計及材質對股骨的影響，此外，亦從完整考慮到形變能及體變能之最大應變能密度觀點去進行探討。
從本論文之討論中，可得到下列結論：有柄式骨柄建議使用應力遮蔽小之鈦合金材質，球頭建議使用耐磨耗之鈷鉻鉬合金材質；無柄式及表面置換型建議使用耐疲勞之鈷鉻鉬合金材質。有柄式以應力遮蔽最小且破壞機率最低之CHS設計較佳；無柄式以破壞機率最低且手術簡易之杯蓋式Money設計較佳；表面置換新型設計不僅能降低應力且破壞機率低，故較舊型好；空心骨柄設計在骨頭完全長入之情形下，其破壞機率較實心高；三大類人工髖關節中，以表面置換型之應力分佈與完整股骨最為接近；無柄骨板式植入物中，骨板上端有固定螺絲之設計可大幅降低螺絲應力。期望本論文研究之結果對改進人工髖關節之設計參考及臨床使用有所幫助。

The replacements of artificial hip joints, historically developed over one century, have shown the most significant progress among all artificial joint surgery. But from clinical observations, there still remain two problems as follows: (1) bone marrow cavity is contaminated by debris from joint wear, and then followed by osteolysis; (2) the femur subject to stress shielding caused osteoporosis. The total hip replacement was quite time-consuming, large bone mass loss, and reduced successful rate of the revision surgery. For the patients with partial cartilage degeneration or bone necrosis, the non-stemmed or resurfacing hip replacement were invented to overcome such complications. This purpose of this study was to investigate the influences of the designs and materials of the hip prostheses on the load-transferring mechanism by finite element method. The results of the current study give further insight into the influences of the hip prostheses on the proximal femur.
The geometry of the femur was three-dimensionally established from the computed tomography scanning images by Amira software. The solid models of the femur and the instrumented hip prostheses were created by SolidWorks software. The body load and muscle forces were applied on the femur, and the distal femur was fixed to simulate one-legged stance loading condition. For four materials of implants (Ti alloy, CoCrMo alloy, pure PEEK (Polyetheretherketone), and 30% Carbon Fiber Reinforced PEEK) and different shape designs of three kinds of implants (stemmed/non-stemmed/resurfaced hip joint), three–dimensional finite element analyses were performed using the commercial package, COSMOSWorks. The objective of this study was to respectively discuss the influences of the designs and materials of the implants on the femur using the von Mises stress criterion, and maximum tensile stress of the implant. In addition, the strain energy density (SED) criterion combined with distortional and dilatational energy was also considered.
The results of this study suggested the following conclusions: the stems of stemmed hip joints should be made of Ti alloy with the slightest stress shielding effect, and the heads of stemmed hip joints should be made of wear-resistant CoCrMo alloy; non-stemmed and resurfaced hip joints should be made of CoCrMo alloy with good fatigue performance. The above held the best results on the CHS design with the slightest stress shielding effect and the lowest fracture rate among stemmed hip joints, and the best results on the cupped Money design with the lowest fracture rate and easy surgery among non-stemmed hip joints; the new design of the resurfaced implants was better than the old one because of decreasing the stress of the femur and implant and lower fracture rate; the fracture rate of the hollow stemmed hip joint with complete ingrowth of bone was higher than the solid one; among three types of artificial hip joint, the stress distribution of the resurfaced hip joint was the very closest to the intact; the design of the plate with proximally fixed screw of non-stemmed implant with plate could decrease substantially the stress of other screws. This study could assist the engineers to improve the design of artificial hip joints and help the surgeons select suitable artificial hip joints for their patients.

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