经前路颈椎多节段椎管扩大术的实验研究

目的设计颈椎前路椎管扩大术式并探讨该术式的可行性,为颈椎管多节段狭窄症提供新的手术方法。方法标本实验:选用4具C1～T1尸体颈椎标本,去除前方肌肉,保留后侧肌肉及固有韧带,解剖出横突孔,沿椎动脉走行,穿入直径3mm橡胶管,注入造影剂。沿C4～6椎体前正中纵行劈开,依次横向撑开3、6、9、12mm,并用木块填塞,三维CT下观察椎管前后径、横径、截面积、两侧椎动脉的直径、间距,神经根管变化。动物实验:用4只成年绵羊,麻醉后暴露出C3,4颈椎前方,将C3,4椎体纵向劈开,横向撑开9mm,取同侧胫骨9mm×9mm×15mm骨块植入撑开区。术后观察四肢运动恢复情况。结果标本在撑开3、6、9mm后,椎管前后径平均增加1.14%、3.53%、5.15%,横径增加7.92%、14.62%、22.74%,截面积增加8.52%,17.99%,25.01%;在撑开3、6、9mm时,两侧椎动脉走行间距平行,撑开12mm时,在C3,4和C6,7椎间椎动脉间距相差2mm,但走行无折屈、受压。撑开前后神经根管各径及长度无变化。标本在撑开3、6、9mm时未见骨折,撑开12mm时2具左侧、1具右侧椎板靠近棘突部骨折,均为裂纹骨折,无移位。4只绵羊术后第2d四肢可以自由行走,无神经、血管损伤征兆。结论经前路颈椎体纵向劈开扩大术,可以增加椎管容积、不影响脊柱三柱稳定结构。动物实验表明椎体横向撑开一定范围内(≤9mm)对颈髓及周围组织无损伤迹象。实验结果初步证实经前路颈椎椎管扩大术安全有效。

Experiment study of anterior enlargement of cervical spine canal

Objective To determinate the feasibility of a new designed anterior enlargement of the cervical spine canal through vertebral body and provide a new method for the treatment of the multi-level cervical spondylosis. Methods (1) Specimen experiment: Cervical spine in 4 corps were involved in this stugy. The anterior surrounding soft tissues were detached and the posterior soft tissues and the intrinsic ligaments were left intact. The vertebral foramina were dissected and latex pipe in 3 mm diameter was inserted as the vertebral artery. Then contrast agent was injected into the pipe. The C4 to C6 vertebral bodies were split longitudinally along the midline to the posterior longitudinal ligament, and then the gap was separated to 3, 6, 9 and 12 mm in turn and the anterior-posterior, transverse diameter, section area of the canal, the distance between the vertebral arteries and the change of neural foramen were observed on the CT scan respectively. (2) Animal experiment: Four adult sheep were used for animal experimental study. The C3 to C4 vertebra were split longitudinally through anterior approach and enlarged the gap to 9 mm then with bone graft.. Results When the gaps were separated to 3, 6, 9 mm. the anterior-posterior diameter of the canal were increased by 1.14%, 3.53 % and 5.15%, the transverse diameter increased by 7.92%, 14.62% and 22.74%, the cross-section area increased by 8.52%, 17.99% and 25.10% respectively. The vertebral arteries run parallel without distortion and there was no fracture found when the enlargement less than 9 mm. The fracture with minimal displacement were found in the junction of the lamina and spinous process in 3 of 4 specimens when the gap was enlarged to l2 mm. Animal experiment demonstrated that the animal could move the extremities freely the day after the operation. Conclusion Anterior enlargement of the cervical spine canal can significantly increased volume as well as depress anterior part of the spinal cannel. Bone can be obtained union and increased the stability without damage the three columns structure. Animal experiment shows there is no damage to spinal cord and surrounding tissues when the vertebral body was separated < 9 mm and the anterior enlargement of the canal is safe and feasible.