Department of Orthopaedic Surgery, National Hospital Organization Osaka Minami Medical Center, Kawachinagano, Osaka, Japan.
J Neurosurg Spine. 2012 Sep;17(3):256-62. doi: 10.3171/2012.6.SPINE12227. Epub 2012 Jul 13.
Although the anatomy of the thoracic pedicle in adolescent idiopathic scoliosis is well known, that of the lumbar pedicle in degenerative lumbar scoliosis is not. The morphometric differences between the pedicles on the concave and convex sides can result in an increased risk of malpositioned pedicle screws. The purpose of this study was to analyze the lumbar pedicle morphology in degenerative lumbar scoliosis using multiplanar reconstructed CT.
The study group comprised 16 consecutive patients (1 man and 15 women, mean age 70.9 ± 4.5 years) with degenerative lumbar scoliosis characterized by a Cobb angle of at least 30° who underwent preoperative helical CT scans. The CT data in DICOM format were reconstructed, and the following parameters were measured for each pedicle inside the curves: the inner cortical transverse pedicle width (TPWi) and outer cortical transverse pedicle width (TPWo) and axial angle, all on an axial plane, and the inner cortical minimum pedicle diameter (MPDi) and outer cortical minimum pedicle diameter (MPDo) and cephalocaudal inclination of the pedicle, all on the plane perpendicular to the pedicle axis. The cortical thickness and cortical ratio of the pedicles on the axial plane and the plane perpendicular to the pedicle axis were calculated. Data were obtained for a total of 124 pedicles; L-1, 26 pedicles in 13 patients; L-2, 32 pedicles in 16 patients; L-3, 32 pedicles in 16 patients; L-4, 28 pedicles in 14 patients; and L-5, 6 pedicles in 3 patients.
Among the target vertebrae, the TPWi, MPDi, and MPDo were significantly smaller and the axial angle was significantly larger on the concave side than on the convex side (TPWi, 6.37 vs 6.70 mm, p < 0.01; MPDi, 5.15 vs 5.67 mm, p < 0.01; MPDo, 7.91 vs 8.37 mm, p < 0.05; axial angle, 11.79° vs 10.56°, p < 0.01). The cortical ratio of the pedicles was larger on the concave side than on the convex side (on the axial plane, 0.29 vs 0.26, p < 0.05; on the plane perpendicular to the pedicle axis, 0.36 vs 0.32, p < 0.01). These differences were most evident at L-4.
This study demonstrated lumbar pedicle asymmetry in degenerative lumbar scoliosis. The authors speculate that these asymmetrical changes were attributed to the remodeling caused by axial load imbalance and the limited space available for pedicles on the concave side. On the concave side, because of the narrower pedicle diameter and larger axial angle, surgeons should carefully determine screw size and direction when inserting pedicle screws to prevent possible pedicle wall breakage and neural damage.
尽管青少年特发性脊柱侧凸的胸椎椎弓根解剖结构已广为人知，但退行性腰椎侧凸的腰椎椎弓根解剖结构却鲜为人知。凹侧和凸侧椎弓根的形态差异可能导致椎弓根螺钉位置不当的风险增加。本研究旨在使用多平面重建 CT 分析退行性腰椎侧凸的腰椎椎弓根形态。
本研究纳入了 16 例连续的退行性腰椎侧凸患者（1 名男性和 15 名女性，平均年龄 70.9±4.5 岁），这些患者的特征为 Cobb 角至少为 30°，术前均接受了螺旋 CT 扫描。将 DICOM 格式的 CT 数据进行重建，并在每个曲度内的每个椎弓根上测量以下参数：在轴位上测量内皮质横径（TPWi）和外皮质横径（TPWo）和轴向角，在垂直于椎弓根轴的平面上测量内皮质最小椎弓根直径（MPDi）和外皮质最小椎弓根直径（MPDo）和椎弓根的头侧尾侧倾斜度。计算轴位和垂直于椎弓根轴的平面上的皮质厚度和皮质比。总共获得了 124 个椎弓根的数据；L-1，13 名患者的 26 个椎弓根；L-2，16 名患者的 32 个椎弓根；L-3，16 名患者的 32 个椎弓根；L-4，14 名患者的 28 个椎弓根；L-5，3 名患者的 6 个椎弓根。
在目标椎体中，凹侧的 TPWi、MPDi 和 MPDo 明显小于凸侧，轴向角明显大于凸侧（TPWi，6.37 比 6.70mm，p<0.01；MPDi，5.15 比 5.67mm，p<0.01；MPDo，7.91 比 8.37mm，p<0.05；轴向角，11.79°比 10.56°，p<0.01）。凹侧的皮质比大于凸侧（轴位，0.29 比 0.26，p<0.05；垂直于椎弓根轴的平面，0.36 比 0.32，p<0.01）。在 L-4 处这些差异最为明显。
本研究显示退行性腰椎侧凸的腰椎椎弓根不对称。作者推测，这些不对称的变化是由轴向负荷不平衡引起的重塑和凹侧椎弓根可用空间有限造成的。在凹侧，由于椎弓根直径较窄，轴向角较大，外科医生在插入椎弓根螺钉时应仔细确定螺钉的大小和方向，以防止可能的椎弓根壁破裂和神经损伤。
