单侧椎弓根钉内固定建立新型山羊脊柱侧凸模型的实验研究

目的探讨未成年山羊脊柱单侧椎弓根钉内固定并对侧肋骨切除建立新型脊柱侧凸模型的可行性。方法实验对象为14只雌性山羊,年龄5~8周,体重6~8kg。在全麻下进行模型制作,T5~L2做右旁正中皮肤切口,分别于脊柱左侧T6,7和T12、L1部位置入特制椎弓根螺钉,经皮下及肌肉下插入1枚不锈钢棒置入螺钉槽口内,远近端螺钉之间适当加压使脊柱向右凸;然后于脊柱右侧分别切除第7~12肋骨2~3cm左右。术后即刻及每4周拍摄正侧位X线片,观察山羊在生长过程中脊柱弯曲的变化。结果1只小羊因麻醉过量,术中死亡;另1只因术后感染而导致内固定失败,观察终止。其余12只小羊中,11只小羊X线片显示右侧侧凸畸形,并且Cobb角随时间延长而增大。只有1只羊术后Cobb角没有进展。术后即刻Cobb角平均为29.0°(23.0°~38.5°),8~10周后Cobb角增至平均43.0°(36.0°~58.0°),平均进展14.0°。术后8周(1只为10周)时获取脊柱标本,去除内固定后发现所有弯曲均为结构性。从脊椎的旋转和外观方面来看,均与特发性脊柱侧凸畸形相似。结论单侧椎弓根钉内固定是一种比较可靠的建立脊柱侧凸模型的方法,模型与特发性脊柱侧凸相似,适用于脊柱侧凸畸形的实验研究。

Unilateral pedicle screws asymmetric tethering: a new method to create a model of idiopathic scoliosis in goat

Objective To evaluate the feasibility of unilateral pedicle screws asymmetric tethering in concave side in combination with ribs resection in convex side for creating a new goat model of idiopathic-type scoliosis. Methods Forteen female goats (age 5-8 week-old, weight 6-8 kg) were used to perform pedicle screws asymmetric tethering and ribs resection. General anesthesia was applied during the procedure. Skin incision was from T₅ to L₂ in the right paramidline. Four special designed pedicle screws were inserted in the left pedicle of T₆, T₇, L₁ and L₂. A prebending stainless steel rod was set percutaneously. The screws were compressed to create a right thoracic curve. Then in the right thorax, 2 to 3 cm of T_7-12 rib was resected in a standard subperiosteal manner. Dorsoventral and lateral plain radiographs were taken for each thoracic spine, both immediately following surgery and every 2 weeks after the procedures. Cobb angles were measured based in the plain radiograph. Results Two goats were excluded for death and infection. Eleven goats showed scoliosis with convex toward to the right side, and the curve increased with time, only one goat exhibited no progression. The initial curves created after the procedures measured an average angle of 29.0° (23.0°-38.5°) and progressed to an average angle of 43.0° (36.0°-58.0°) over 8 to 10 weeks. The average progression of 14.0° was observed. The immediate curvature did have a highly significant correlation with the final curvature (p<0.001). The curves showed structured scoliosis when the goats were harvested after 8 weeks (1 goat at 10th weeks) of the procedures. Conclusion All goats with progressive curves show a typical, idiopathic-type scoliosis involving a right rib prominent and a left depressed thoracic cage. Unilateral pedicle screws asymmetric tethering is a practical method to create experimental scoliosis model in goat.