Rady Children’s Hospital and Health Center San Diego, CA, San Diego, CA, USA.
Spine (Phila Pa 1976). 2012 Aug 15;37(18):1566-72. doi: 10.1097/BRS.0b013e318252ccbe.
Prospective case series.
To evaluate the change in spinal rod contour from before implantation to after surgical correction of thoracic curves in patients with adolescent idiopathic scoliosis.
With segmental pedicle screw spinal instrumentation and vertebral derotation, many authors have reported a loss of thoracic kyphosis postoperatively. Although surgeons anticipate some flattening of the preimplantation rod contour in the sagittal plane, the magnitude of this change in shape has not been documented.
The concave and convex rod shapes of 5.5-mm ultrahigh-strength steel spinal rods (200 KSI) from patients with thoracic adolescent idiopathic scoliosis (n = 27), which were contoured with benders by the surgeon, were traced prior to insertion. Postoperative (average, 5 weeks) sagittal rod shape was determined from lateral 2-dimensional radiographs. Maximal rod deflection and angle of the tangents to rod end points (Cobb) were measured. Repeated measures analysis of variance assessed differences between pre- and postoperation.
The scoliosis of 55° ±14° was corrected 72% to 15° ± 5°. The preinsertion rod shapes were more kyphotic for the concave (45.6°) than for the convex (31.4°) rods. Following correction, the concave rods flattened, with decrease in deflection of 13 mm and reduction in angle of 21° (both P < 0.001). The convex rods increased 1.5 mm in deflection and 2° in angle (P < 0.01, P = 0.18). The sagittal profile was maintained postoperatively as measured from T5-T12: 19° ±14° versus 22° ± 6° (pre vs. post, P > 0.1).
We found a significant difference between pre- and postoperative rod contour, particularly for concave rods. Rod overcontouring (by ~20° for concave rod) resulted in high degrees of correction without loss of sagittal alignment. The resulting deformations are likely associated with substantial in vivo deforming forces.
前瞻性病例系列研究。
评估青少年特发性脊柱侧凸患者胸椎曲度矫正术后脊柱棒轮廓的变化。
使用节段性椎弓根螺钉脊柱器械和椎体旋转，许多作者报道术后胸段后凸丢失。尽管外科医生预计在矢状面植入前脊柱棒的轮廓会有一定程度的变平，但这种形状变化的幅度尚未记录。
对 27 例青少年特发性脊柱侧凸伴胸段脊柱的患者（200 KSI）使用 5.5 毫米超高强度钢脊柱棒，由外科医生使用弯曲机进行塑形，在插入前对其凹面和凸面的棒形进行跟踪。术后（平均 5 周）通过侧位二维射线照相确定矢状面棒形。测量最大棒挠度和棒端点切线的角度（Cobb）。重复测量方差分析评估术前与术后之间的差异。
55°±14°的脊柱侧凸矫正至 15°±5°。凹面（45.6°）比凸面（31.4°）棒更具后凸。矫正后，凹面棒变平，挠度减少 13 毫米，角度减少 21°（均 P<0.001）。凸面棒的挠度增加 1.5 毫米，角度增加 2°（P<0.01，P=0.18）。术后从 T5-T12 测量的矢状位形态保持不变：19°±14°与 22°±6°（术前与术后，P>0.1）。
我们发现术前和术后棒轮廓有显著差异，特别是凹面棒。棒过度塑形（凹面棒约 20°）导致高度矫正而不丢失矢状位对齐。由此产生的变形可能与体内大量的变形力有关。
