经后路短节段椎弓根内固定治疗胸腰椎爆裂型骨折的远期疗效

The long term results of thoracolumbar burst fractures treated with short segment pedicle instrumentation

目的探讨经后路短节段椎弓根内固定治疗胸腰椎爆裂型骨折的远期疗效。方法经后路切开复位、短节段椎弓根内固定术后随访5年以上的胸腰椎单节段爆裂型骨折68例,随访时间5～13年(平均8年)。68例均于术前、术后、内固定取出前、末次随访时拍摄胸腰椎正侧位X线片,其中18例于末次随访时行CT检查。结果(1)术前有不完全性神经损伤者随访时有90.3%(28/31)恢复Frankel分级1级或以上,完全性神经损伤者无明显恢复。腰痛按Denis评分,P1 41例,P2 24例,P3 3例。(2)内固定螺帽、螺钉松动各1例,螺钉折弯2例,螺钉折断7例,8例未及时取出内固定者2例出现切口破溃渗液。(3)与术前相比伤椎前缘高度平均矫正30.5%,Cobb角平均矫正5.8°。矫正度丢失以伤椎上方椎间隙为主,其次是下方椎间隙;伤椎前缘高度平均丢失1.9%,中部6.0%。(4)伤椎高度丢失和塌陷以椎体中部最重,CT显示88.9%(16/18)的患者伤椎椎体内存在空隙,且与上方椎间隙延续;伤椎复位后可呈“杯状”畸形。(5)伤椎上下方椎间隙较术前退变狭窄,甚至消失;5例Cobb角大于20°者3例有腰痛,其中1例还有轻度神经受压表现;椎间隙退变狭窄与腰痛无相关性。结论经后路短节段椎弓根内固定治疗胸腰椎爆裂型骨折有利于恢复神经功能、伤椎高度和生理曲度;

Objective To analyze the long term results of thoracolumbar burst fractures treated with short segment pedicle instrumentation. Methods Sixty eight cases of thoracolumbar burst fractures fixed with short segment pedicle instrumentation were followed up for at least 5 years (5-13 years, average 8 years). All of them were checked with radiography pre and post operation and before implant removal. At final follow up assessment, all were examined with radiography, 18 cases were checked with CT scan as well. Results 1) Neurological status improved at least 1 Frankel grade in 90.3% of the patients who had preoperative incomplete paraplegia, while no improvement was obtained in those who had preoperative complete paraplegia. Low back pain was evaluated according to Denis Pain Scale, the results showed P1 41 cases (60.3%), P2 24 cases (35.3%), P3 3 cases (4.4%). 2) The shortest distances between the upper and lower pedicle screws tips shortened for 0-6.5 mm (average 2.5 mm) before removal in contrast to that at post operative immediately. Of the 68 cases, nuts loosened in 1 case, pedicle screws loosened in 1 case, bent in 2 cases and broken in 5 cases. Of the 8 cases whose implants were not removed timely, screw broke in 2 cases, and seepage occurred through incision in 2 cases. 3) At final follow up, the correction of anterior vertebral body height averaged 30.5%, and Cobb angle 5.8°, despite a mean correction loss of Cobb angle 12.1°. Correction loss was most evident at the above disc spaces, then the below disc spaces. Correction loss of vertebral body height averaged 1.9% in the anterior, and 6.0% in the middle part. 4) The collapse of vertebral body was most serious in the middle part. The deformity of 'codfish vertebrae' occurred in the superior part of vertebrae body in 21 cases, among them the upper adjacent vertebral body sank into the injured body in 5 cases, 3 of whom engendered kyphoses greater than 25°. Evident intra corporeal gaps were found in 16 of 18 patients who were checked with CT, and the gaps communicated with the above disc space. The fractured body could have a deformity of the 'cup' after reduction. 5) Degeneration and narrowing of the disc spaces next to fractured vertebrae were very common, and the above space disappeared in 27 cases, while the lower space disappeared in 14 cases. The upper disc space adjacent to fixation levels degenerated in 1 of 8 cases whose implants were not removed timely. Five patients had Cobb angle greater than 20°, three of them had low back pain, and one had mild symptom of nerve compromise. Low back pain was not correlated with degeneration of discs. Conclusion Short segment pedicle instrumentation provides satisfying stability for thoracolumbar burst fractures. It helps physiologic postural contour restoration and facilitates neural recovery, but is associated with relatively high rates of implant failure and correction loss which is most evident at adjacent discs spaces. Deficiency of bone grafting and delayed implant removal are the most probable causes for correction loss.