Prasad Prashant Kumar, Salunke Pravin, Sahni Daisy, Kalra Parveen
Department of Neurosurgery, PGIMER, Chandigarh, India.
Department of Anatomy, PGIMER, Chandigarh, India.
J Craniovertebr Junction Spine. 2017 Oct-Dec;8(4):354-358. doi: 10.4103/jcvjs.JCVJS_109_17.
The existing literature on lateral atlantoaxial joints is predominantly on bony facets and is unable to explain various C1-2 motions observed. Geometric morphometry of facets would help us in understanding the role of cartilages in C1-2 biomechanics/kinematics.
Anthropometric measurements (bone and cartilage) of the atlantoaxial joint and to assess the role of cartilages in joint biomechanics.
The authors studied 10 cadaveric atlantoaxial lateral joints with the articular cartilage and after removing it, using three-dimensional laser scanner. The data were compared using geometric morphometry with emphasis on surface contours of articulating surfaces.
The bony inferior articular facet of atlas is concave in both sagittal and coronal plane. The bony superior articular facet of axis is convex in sagittal plane and is concave (laterally) and convex medially in the coronal plane. The bony articulating surfaces were nonconcordant. The articular cartilages of both C1 and C2 are biconvex in both planes and are thicker than the concavities of bony articulating surfaces.
The biconvex structure of cartilage converts the surface morphology of C1-C2 bony facets from concave on concavo-convex to convex on convex. This reduces the contact point making the six degrees of freedom of motion possible and also makes the joint gyroscopic.
现有关于寰枢外侧关节的文献主要集中在骨小关节面，无法解释所观察到的各种C1 - 2运动。小关节面的几何形态测量将有助于我们理解软骨在C1 - 2生物力学/运动学中的作用。
对寰枢关节进行人体测量（包括骨骼和软骨），并评估软骨在关节生物力学中的作用。
作者使用三维激光扫描仪研究了10个保留关节软骨和去除关节软骨后的尸体寰枢外侧关节。使用几何形态测量法对数据进行比较，重点关注关节面的表面轮廓。
寰椎的骨性下关节面在矢状面和冠状面均为凹面。枢椎的骨性上关节面在矢状面为凸面，在冠状面外侧为凹面、内侧为凸面。骨性关节面不匹配。C1和C2的关节软骨在两个平面均为双凸面，且比骨性关节面的凹面更厚。
软骨的双凸结构将C1 - C2骨小关节面的表面形态从凹对凹凸转变为凸对凸。这减少了接触点，使六个自由度的运动成为可能，并且使关节具有陀螺效应。
