Gehweiler Dominic, Wähnert Dirk, Meier Norbert, Spruit Maarten, Raschke Michael Johannes, Richards Robert Geoff, Noser Hansrudi, Kamer Lukas
AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland.
Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany.
J Orthop Res. 2017 Oct;35(10):2154-2163. doi: 10.1002/jor.23512. Epub 2017 Jan 30.
The surgical fracture fixation of the odontoid process (dens) of the second cervical vertebra (C2/axis) is a challenging procedure, particularly in elderly patients affected by bone loss, and includes screw positioning close to vital structures. The aim of this study was to provide an extended anatomical knowledge of C2, the bone mass distribution and bone loss, and to understand the implications for anterior screw fixation. One hundred and twenty standard clinical quantitative computed tomography (QCT) scans of the intact cervical spine from 60 female and 60 male European patients, aged 18-90 years, were used to compute a three-dimensional statistical model and an averaged bone mass model of C2. Shape and size variability was assessed via principal component analysis (PCA), bone mass distribution by thresholding and via virtual core drilling, and the screw placement via virtual positioning of screw templates. Principal component analysis (PCA) revealed a highly variable anatomy of the dens with size as the predominant variation according to the first principal component (PC) whereas shape changes were primarily described by the remaining PCs. The bone mass distribution demonstrated a characteristic 3D pattern, and remained unchanged in the presence of bone loss. Virtual screw positioning of two 3.5 mm dens screws with a 1 mm safety zone was possible in 81.7% in a standard, parallel position and in additional 15.8% in a twisted position. The approach permitted a more detailed anatomical assessment of the dens axis. Combined with a preoperative QCT it may further improve the diagnostic procedure of odontoid fractures. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2154-2163, 2017.
第二颈椎（C2/枢椎）齿突的手术骨折固定是一项具有挑战性的操作，尤其是对于受骨质流失影响的老年患者，并且包括靠近重要结构的螺钉定位。本研究的目的是提供C2的详细解剖学知识、骨量分布和骨质流失情况，并了解其对前路螺钉固定的影响。使用来自60名年龄在18 - 90岁的欧洲男性和60名欧洲女性患者的120例完整颈椎的标准临床定量计算机断层扫描（QCT），来计算C2的三维统计模型和平均骨量模型。通过主成分分析（PCA）评估形状和大小变异性，通过阈值分割和虚拟取芯钻孔评估骨量分布，并通过螺钉模板的虚拟定位评估螺钉放置。主成分分析（PCA）显示齿突的解剖结构高度可变，根据第一主成分（PC），大小是主要变化因素，而其余主成分主要描述形状变化。骨量分布呈现出特征性的三维模式，并且在存在骨质流失的情况下保持不变。在标准平行位置，81.7%的情况下可以虚拟放置两个3.5毫米的齿突螺钉并留出1毫米的安全区，在扭转位置还有额外15.8%的情况可行。该方法允许对齿突轴进行更详细的解剖学评估。结合术前QCT，它可能进一步改善齿突骨折的诊断程序。©2017骨科研究协会。由威利期刊公司出版。《矫形外科研究杂志》35:2154 - 2163，2017年。
