下顎骨複合骨折固定方法之生物力學研究

Biomechanical study of fixation in combined mandibular fracture

顏呈育(Cheng-Yu Yan)

指導教授 ： 林鼎勝

義守大學/醫學科技學院/生物醫學工程學系/碩士(2022年)

摘要

下顎骨骨折(Mandibular fracture)機率為顏面骨之首，現今研究大多探討下顎骨單處骨折之固定方式，對於下顎骨複合骨折卻乏人問津，而本研究針對臨床上較常發生的下顎副聯合處斷裂伴隨單邊下顎髁突骨折作進一步的探討。
　　對於下顎骨髁突處(Condyle)骨折及下顎骨副聯合處(Para-symphysis)骨折之複合性骨折固定方式眾說紛紜，因此本研究依據文獻內容及臨床需求，對於下顎骨髁突骨折的固定方式分為S4、M4、DM4+4、DM2+2及DM4+2五個組別；對於下顎骨副聯合處骨折的固定方式則分為S4、D4+4、D4+2、D2+2、PD4+4、PD4+2及PD2+2七個組別，排列組合後共計35種固定方式。本研究欲藉由電腦有限元素分析針對不同骨板尺寸及骨板排列的固定方式來研究下顎骨副聯合處及髁狀突之複合骨折固定的生物力學穩定度。
　　由模擬下顎各肌肉施力的應力結果顯示，骨板/骨釘的應力值遠大於鈦合金之降伏應力，代表不論以何種固定方式均不建議患者於術後立即張口，會使骨板/骨釘斷裂或曝露於軟組織。經由單側咬合力的模擬結果推論，選用S4_PD4+2組(髁突處採單一四孔骨板搭配副聯合處垂直放置單一四孔＋單一三孔骨板)的固定方式，能有效提供下顎骨穩定性。綜觀兩種施力模式下的骨板應力值，可推論於髁突處適合以單一骨板固定，搭配副聯合處採用兩塊骨板垂直放置，可降低骨板上之應力，減少骨板斷裂或曝露於軟組織之風險。
　　將兩種施力結果做全因子分析，由結果可看出下顎副聯合處的固定方式對於副聯合處及髁突處兩個斷裂位置產生一定的影響程度，因此將副聯合處使用兩塊骨板垂直放置，可降低髁突處骨板的應力集中現象，並由模擬結果可推論於副聯合處使用兩塊骨板垂直放置，可減少於髁突處放置植入物的數量，亦可提供相對應的穩定性。

關鍵字

下顎骨複合骨折 ； 下顎副聯合 ； 下顎髁突 ； 開放復位及內固定 ； 穩固性

並列摘要

From the retrospective studies, mandible fractures had the highest incidence among the facial bone fractures. Most of the current researches focus on the fixation of single mandibular fractures, but seldom studies discuss about the complex fractures of the mandible, especially the mandibular para-symphysis fractures combined with unilateral mandibular condyle fractures, which are frequently observed in clinical practice.
Currently there is no consensus on the fixation of complex mandibular fractures involving condyle fracture and para-symphysis fracture at the same time. Therefore, according to the literature and clinical needs, this study investigated the combination of mandibular condyle fractures with five fixation methods (S4, M4, DM4+4, DM2+2 and DM4+2) and mandibular para-symphysis fractures with seven fixation methods (S4, D4+4, D4+2, D2+2, PD4+4, PD4+2 and PD2+2). Therefore, a total of 35 combination of fixation methods were produced. This study conducted finite element analysis to evaluate the biomechanical stability of the fixation for complex mandibular fractures.
The simulation results showed that the normal mandibular muscle forces would jeopardize the stability of the fixation after surgery, which implied the possible bone plate/screw breakage or soft tissue exposure. The simulation results of unilateral occlusal force showed that the fixation method of the S4_PD4+2 group (single four-hole plate at the condyle and perpendicular single four-hole + single three-hole plate at the mandibular para-symphysis) could effectively improve the stability of the mandible. By observing the stress values of the plate under two loading types used in this study, it could be deduced that a single bone plate fixation at the condyle combined with perpendicular double plates fixation at the para-symphysis was benefit to the biomechanical stability.
The results of full factorial analysis showed that the fixation method of the para-symphysis has a certain degree of influence on both the para-symphysis and the condyle fracture sites. Perpendicular double plates fixation at the para-symphysis would reduce the stress concentration of the bone plate at the condyle. From the results of this study, it can be inferred that perpendicular double plates fixation at the para-symphysis could reduce the number of implants placed at the condyle and provide correspondingly sufficient stability.

並列關鍵字

mandibular fracture ； complex fracture ； mandibular para-symphyseal ； mandibular condyle ； open reduction ； internal fixation ； stability

參考文獻

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