在現今醫療器材,鈦合金或不銹鋼最常用來製作骨折固定器之材料,如骨釘、骨板等。這些金屬的骨折固定器不但具有金屬離子析出因而造成人體過敏現象的風險。同時當骨折部位癒合後仍需再進行二次手術取出固定物,造成病患再一次疼痛及傷口感染的風險。目前以聚乳酸(Polylactide, PLA)製成之生物可降解骨釘、骨板具有不需二次手術取出的優勢,但其強度不足的問題使得目前仍無法廣泛運用於大部份骨折的固定治療。本研究以聚乳酸(PLA)為基材,並運用熱處理提高基材之結晶度,達成聚乳酸(PLA)骨釘、骨板強度提升的目標。研究中以CAE軟體模擬感應線圈加熱之模具溫度變化,藉此設計出適當之模具加熱系統。接著再以田口法進行實驗設計,根據可吸收骨釘骨板力學測試規範「ASTM F2502」,以骨板的四點抗彎強度為品質之望大目標,同時列出各項射出條件、材料參數及製程參數控制因子,建立各因子水準實驗表。 本研究以材料試驗機探討聚乳酸(PLA)骨釘、骨板之機械強度。最後依據直交表實驗結果,以ANOVA統計分析建立出高強度聚乳酸(PLA)骨釘、骨板之最佳材料及製程參數,以提供產業發展高附加價值之可吸收性高分子骨釘、骨板之重要參考。
Titanium alloy & stainless steel are major materials for bone fracture fixation such as bone screws and plates in today's medical devices. However, the fixation devices made of metal not only have the risk of metal ion release to cause human allergies, but they also need to be removed by a second surgical operation making pain and the risk of the patient’s wound infection after the bone fracture healing. The biodegradable Polylactic Acid (PLA) bone screws & bone plates have the great advantage of not needing a second operation, but their insufficient strengths make them not be widely used in the current bone fracture fixation. In the study, we use PLA as the matrix, using heat treatment to improve PLA’s crystallinity and strength. In the study, we use CAE to simulate mold’s temperature and design the heating system. Regarding ASTM F2502 “Standard Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants”, we design the experiments by Taguchi method to establish the orthogonal array with the 4-point bending strength to be “larger the better” quality characteristic and injection conditions, material & process parameters to be control factors. In the study, we use Material Testing Machine to test PLA’s strength. Finally, according to the experimental results of orthogonal array, the best material and process parameters of high strength of PLA bone screws & bone plates are found by ANOVA statistical analysis. It will provide a practical and important reference for the industry to develop high value-added absorbable polymer bone screws & bone plates.