Department of Neurosurgery, Tulane Center for Clinical Neurosciences, Tulane University School of Medicine, 131 S. Robertson St. Suite 1300, New Orleans, LA, 70112, USA.
Department of Neurology, Tulane Center for Clinical Neurosciences, Tulane University School of Medicine, New Orleans, LA, USA.
Surg Radiol Anat. 2022 Mar;44(3):423-429. doi: 10.1007/s00276-022-02901-2. Epub 2022 Feb 25.
Potential asymmetries of the C2 posterior elements pose a problem for the spine surgeon seeking to make the best choice for spinal stabilization while reducing morbidity.
A digital caliper was used to measure the pars interarticularis height and length on left and right sides of 25 adult C2 vertebrae. The pars interarticularis was defined as the bone between the posterior most aspect of the superior articular process and the anterior most aspect of the inferior articular process of C2. Also, the C2 vertebrae from 49 patients were scanned by CT. Parasagittal images were reviewed and using the same definitions as were used for the skeletal specimens, the length and the height of the C2 pars interarticularis from both the left and right sides were measured using CT. The image slices were acquired at 3 mm intervals. The pars interarticularis height was determined on sagittal CT reconstruction, while the pars interarticularis length was calculated on the basis of the axial images.
The lengths and the heights of the left and right pars interarticularis were compared using CTs of patients and skeletal specimens. No significant differences were found in the length and height measurements of the CT images on both sides. However, in the skeletal specimens, the left and right pars interarticularis did not differ significantly in length but differed significantly in height (p = 0.003). The mean height of the left pars interarticularis was approximately two times larger than the right in the skeletal specimens. Absolute differences were calculated between the side with the greater length and height and the side with the lesser length and height irrespective of their left-right orientations. For CT measurements, most differences in length and height between the greater pars interarticularis and lesser pars interarticularis occurred between 0 and 1 mm with each successive disparity interval yielding lower numbers. Skeletal measurements revealed a similar length disparity distribution to the CT measurements. However, height measurements in the skeletal specimens varied widely. Eight pars interarticularis specimens demonstrated a height difference between 0 and 1 mm. No dry bone pars interarticularis specimens demonstrated a height difference between 1 and 2 mm. The pars interarticularis of nine specimens demonstrated a height difference between 2 and 3 mm. Two demonstrated a height difference between 3 and 4 mm. Four demonstrated a height difference between 4 and 5 mm and two demonstrated a height difference greater than 5 mm. The greater pars interarticularis lengths and heights were combined and compared to their lesser counterparts on CT and skeletal measurements. In all measurements of this type, significant differences were found in the pars interarticularis length and height, whether measured through CT or via digital calipers.
Asymmetry between the left and right C2 pars interarticularis as shown in the present study can alter surgical planning. Therefore, knowledge of this anatomical finding might be useful to spine surgeons.
C2 后弓的潜在不对称性给寻求最佳脊柱稳定选择的脊柱外科医生带来了问题，同时降低发病率。
使用数字卡尺测量 25 个 C2 椎体左侧和右侧的关节突间部高度和长度。关节突间部定义为 C2 后关节突最前缘和下关节突最前缘之间的骨。此外，对 49 例患者的 C2 椎体进行 CT 扫描。对矢状位图像进行回顾性分析，并使用与骨骼标本相同的定义，使用 CT 测量左侧和右侧 C2 关节突间部的长度和高度。图像层间距为 3mm。在矢状位 CT 重建中确定关节突间部高度，在轴向图像上计算关节突间部长度。
使用患者 CT 和骨骼标本比较了左侧和右侧关节突间部的长度和高度。在两侧 CT 图像的长度和高度测量中未发现显著差异。然而，在骨骼标本中，左侧和右侧关节突间部的长度没有显著差异，但高度有显著差异（p=0.003）。骨骼标本中左侧关节突间部的高度约为右侧的两倍。无论其左右取向如何，都计算了具有较大长度和高度的一侧与具有较小长度和高度的一侧之间的绝对差异。对于 CT 测量，较大关节突间部和较小关节突间部之间的长度和高度差异大多在 0 到 1mm 之间，每个连续的差异间隔产生较低的数字。骨骼测量显示出与 CT 测量相似的长度差异分布。然而，骨骼标本的高度测量值差异很大。8 个关节突间部标本的高度差异在 0 到 1mm 之间。没有干骨关节突间部标本的高度差异在 1 到 2mm 之间。9 个标本的关节突间部高度差异在 2 到 3mm 之间。2 个标本的高度差异在 3 到 4mm 之间。4 个标本的高度差异在 4 到 5mm 之间，2 个标本的高度差异大于 5mm。较大的关节突间部长度和高度与 CT 和骨骼测量的较小关节突间部结合并进行比较。在这种类型的所有测量中，无论是通过 CT 还是通过数字卡尺测量，关节突间部的长度和高度都存在显著差异。
本研究显示 C2 两侧关节突间部的不对称性可能改变手术计划。因此，了解这种解剖学发现可能对脊柱外科医生有用。
