Bujtar P, Simonovics János, Váradi Károly, Sándor George K B, Pan Jingzhe, Avery C M E
Department of Maxillofacial Surgery, University Hospitals of Leicester, Leicester, UK.
Br J Oral Maxillofac Surg. 2013 Sep;51(6):479-85. doi: 10.1016/j.bjoms.2012.09.015. Epub 2012 Oct 18.
Osteotomy cuts are typically made using a saw, and the meeting point acts as a focus for the concentration of stress and failure. We have studied the impact of different designs of osteotomy cut. Cadaver sheep tibias were scanned by computed tomography (CT) and transformed into a computer-aided design (CAD) model. A standard marginal resection defect was created and then modified, and a finite element analysis made. The relative stress concentrations at the intersection of osteotomy cuts were recorded using principal stresses S1, S3, and von Mises stress, von Mises under both 4-point bending and torsion testing. The osteotomy designs studied were: right-angled and bevelled osteotomy end cuts, overcutting, and a stop drill hole. Peak stress values for 4-point bending and torsion were 24-30% greater at the right-angled osteotomy than the bevelled end cut. Overcutting dramatically increased peak stress values caused by bending and torsion by 48% and 71%, respectively. Substantially lower concentrations of stress were noted with a stop hole using both a 90° (bending 38% and torsion 56%), and a tangential (bending 58% and torsion 60%) cut. A bevelled osteotomy has substantially lower concentrations of stress than a right-angled osteotomy. It is important to avoid creating an overcut as this causes an appreciable increase in the concentration of stress, while a stop drill hole substantially reduces the stress. The creation of a stop hole and the use of judicious bevelling techniques are modifications in the design of an osteotomy that are readily applicable to surgical practice.
截骨切口通常使用锯子进行，而切口的交汇点成为应力集中和失效的焦点。我们研究了不同截骨切口设计的影响。通过计算机断层扫描（CT）对尸体羊胫骨进行扫描，并将其转化为计算机辅助设计（CAD）模型。创建一个标准的边缘切除缺损，然后进行修改，并进行有限元分析。在四点弯曲和扭转试验下，使用主应力S1、S3和冯·米塞斯应力记录截骨切口交汇处的相对应力集中情况。所研究的截骨设计包括：直角和斜角截骨端切口、过度切割以及止动钻孔。直角截骨处四点弯曲和扭转的峰值应力值比斜角端切口高24% - 30%。过度切割分别使弯曲和扭转引起的峰值应力值显著增加48%和71%。使用90°（弯曲时降低38%，扭转时降低56%）和切向（弯曲时降低58%，扭转时降低60%）切口的止动孔时，应力集中明显降低。斜角截骨的应力集中比直角截骨低得多。避免产生过度切割很重要，因为这会导致应力集中显著增加，而止动钻孔可大幅降低应力。创建止动孔和采用明智的斜切技术是截骨设计中的改进，很容易应用于外科手术实践。
