Miyamoto Hiroshi, Hashimoto Kazuki, Ikeda Terumasa, Akagi Masao
Department of Orthopaedic Surgery, Kindai University Hospital, 377-2, Ohnohigashi, Osaka-Sayama, Osaka, 589-8511, Japan.
Eur Spine J. 2017 Sep;26(9):2380-2385. doi: 10.1007/s00586-017-5106-7. Epub 2017 Apr 27.
Progression of kyphotic deformity at the middle/lower cervical spine can cause difficulty with horizontal gaze, so compensation at other spinopelvic parts may occur. However, the precise mechanism remains unclear. The present study investigated the effect of correction surgery for cervical kyphosis on the compensatory mechanisms in overall spinopelvic sagittal alignment.
Forty-one patients, comprising 23 males and 18 females (mean age 67 years), underwent correction surgery for cervical kyphosis using the posterior screw-rod system. Spinopelvic lateral radiographs in the standing position were taken before and after surgery. C0-1 angle, C1-2 angle, clivo-axial angle (CAA), C2-7 angle, thoracic kyphosis, lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope were measured. Correlations between C2-7 angle and these parameters before surgery, and correlations between the correction angle of cervical kyphosis and postoperative changes of these parameters were evaluated.
Negative correlations were found between the C2-7 angle and CAA (R = -0.640, p < 0.01), and C2-7 angle and C0-1 angle (R = -0.762, p < 0.001) before surgery. Negative correlations were found between the correction angle of C2-7 and change of CAA (R = -0.718, p < 0.001), and between the correction angle of C2-7 and change of C0-1 angle (R = -0.672, p < 0.01) after surgery.
The present study demonstrated that C0-1 angle and CAA are more important in the compensatory mechanism for kyphotic deformity at the middle/lower cervical spine compared to downward parameters. That is, to maintain horizontal gaze, lordosis increases at the cranio-cervical junction with greater kyphosis at the middle/lower cervical spine. Correction of cervical kyphosis in the middle/lower cervical spine resulted in normalization of the C0-1 angle and CAA because the compensatory mechanism at the cranio-cervical junction for obtaining horizontal gaze was no longer necessary after surgical intervention.
中下颈椎后凸畸形进展可导致水平凝视困难，因此可能会在脊柱骨盆的其他部位出现代偿。然而，确切机制尚不清楚。本研究调查了颈椎后凸矫正手术对整个脊柱骨盆矢状面排列代偿机制的影响。
41例患者，包括23例男性和18例女性（平均年龄67岁），采用后路螺钉棒系统进行颈椎后凸矫正手术。术前和术后拍摄站立位脊柱骨盆侧位X线片。测量C0-1角、C1-2角、斜坡-枢椎角（CAA）、C2-7角、胸椎后凸、腰椎前凸、骨盆入射角、骨盆倾斜度和骶骨倾斜度。评估术前C2-7角与这些参数之间的相关性，以及颈椎后凸矫正角度与这些参数术后变化之间的相关性。
术前C2-7角与CAA之间呈负相关（R = -0.640，p < 0.01），C2-7角与C0-1角之间呈负相关（R = -0.762，p < 0.001）。术后C2-7矫正角度与CAA变化之间呈负相关（R = -0.718，p < 0.001），C2-7矫正角度与C0-1角变化之间呈负相关（R = -0.672，p < 0.01）。
本研究表明，与向下的参数相比，C0-1角和CAA在中下颈椎后凸畸形的代偿机制中更为重要。也就是说，为了保持水平凝视，在中下颈椎后凸增加时，颅颈交界处的前凸会增加。中下颈椎后凸的矫正导致C0-1角和CAA正常化，因为手术干预后不再需要颅颈交界处为获得水平凝视而产生的代偿机制。
