对“上胸椎前路逆向椎弓根螺钉内固定技术的可行性研究”一文的看法

The feasibility of the anterior reverse transpedicular screw （ARTPS） fixation at upper thoracic spine

目的：通过放射解剖学研究及标本上的模拟手术操作来验证上胸椎（T1~T4）前路逆向椎弓根螺钉内固定技术的可行性及安全性。方法：在放射科CT数据库中选取40例层厚为0.625mm的正常上胸椎薄层CT扫描数据（男20例，女20例，年龄18～68岁，平均39.7岁），对数据进行MPR重建，在每侧椎弓根轴心上选取其横切面和矢状面进行观察和测量，测得每侧椎弓根的横径、高度、横切面进钉点距离、进钉角度、矢状面进钉点距离、进钉角度、钉道长度，对所得数据进行统计学处理。选取10具（男5例、女5例，年龄不详）完整的成人上胸椎防腐标本（包括C7～T6），外观无畸形和破损，完整保留T1～T4两旁肋椎关节及椎旁软组织，于椎体前方逆向置入椎弓根螺钉，通过X线透视、CT扫描、剖面观察、测量，参照Rao等的椎弓根螺钉穿破分级标准对置钉优良率进行评测。结果：T1～T4椎弓根横径逐渐减小8.14～3.47mm；椎弓根高度逐渐增大6.89～10.29mm；横切面进钉角度逐渐减小32.96°～11.64°；横切面进钉点距离逐渐增大1.80～5.50mm；矢状面进钉角度逐渐增大104.95°～115.74°；矢状面进钉点距离逐渐增大5.95～8.76mm；钉道长度32.95～35.96mm。T3、T4椎弓根横径过于细小，不适合逆向椎弓根螺钉的置入，但在T3、T4逆向置入椎弓根-肋骨复合体螺钉是可行的。T1、T2前路逆向椎弓根螺钉的规格为：直径4.0mm、长度35mm左右，T3、T4前路逆向椎弓根-肋骨复合体螺钉的规格为：直径5.0mm、长度35mm左右。在10具上胸椎标本上共置钉80枚，根据Rao等的椎弓根螺钉穿破分级标准，总体优良率达90%，其中椎弓根侧壁穿破小于2mm未造成脊髓压迫的共7枚；椎弓根内侧壁穿破距离在2～4mm的共有5枚，分别为T1椎体1枚，T3椎体1枚，T4椎体3枚，有不同程度脊髓压迫；椎弓根内侧壁穿破距离大于4mm的2枚，其中T2椎体1枚，T4椎体1枚，脊髓受压严重；T2椎体有1枚椎弓根外侧壁穿破。结论：T1、T2椎体前路逆向椎弓根螺钉内固定技术和T3、T4椎体前路逆向椎弓根-肋骨复合体螺钉内固定技术可达到双皮质固定的目的，但其安全性及临床实用性尚需进一步探讨。

Objectives： To verify the feasibility and safety of the anterior transpedicular screw（ATPS） fixation of the upper thoracic spine（T1-T4） through the radiological anatomy study on the cadaveric specimens. Methods： The upper thoracic spine thin-section CT data of 40 cases were collected from the radiology department′s database（20 males and 20 females, aged from 18 to 68 years, the mean age was 39.7 years）. The data of OPW（outer pedicle width）, OPH（outer pedicle height）, PAL（pedicle axis length）, TPA（transverse section angle）, SPA（sagittal section angle）, DTIP（distance of transverse intersection point） and DSIP（distance of sagittal intersection point） of each pedicle were measured on the transverse and sagittal sections through the axis of each pedicle. The data were recorded and statistically analyzed. 10 upper thoracic spine（C7-T6） specimens of adults（5 males and 5 females, with unknown ages）, with no damage to their appearance, the costovertebral joints and paravertebral soft tissue were completely retained. Then simulate surgical operations were done on the cadaveric specimens based on the obtained data. Screws were implanted anteriorly by free hand. After that, the specimens accepted X-ray fluoroscopy and CT scan. At last, the screws were removed, the specimens were sawed along the transaction and sagittal section of the screw channel. Then the success rate of the screw placement was evaluated according to Rao′s worn out classification standard of pedicle screws. Results： From T1 to T4, the OPW decreased from 8.14mm to 3.47mm; the OPH increased from 6.89mm to 10.29mm; the TPA decreased from 32.96° to 11.64°; the DTIP increased from 1.80mm to 5.50mm; the SPA increased from 104.95° to 115.74°; the DSIP increased from 5.95 to 8.76mm; the PAL changed irregularly, from 32.95 to 35.96mm. The pedicle diameters of T3 and T4 were too small to implant ATPS, but the ARTPS can be implanted successfully. The diameter of ATPS was about 4.0mm; the length of ATPS was about 35mm. The diameter of ARTPS was about 5.0mm; the length of ARTPS was about 35mm. 80 pedicle screws were implanted anteriorly, according to Rao′s worn out classification standard of pedicle screws, the fine rate was 90%. The internal walls of 7 pedicles were broken by screws of less than 2mm and no compression to the spinal cord. The internal walls of 5 pedicles were broken of 2 to 4mm, 1 at T1, 1 at T3 and 3 at T4, with varying degrees of spinal cord compression. The internal walls of 2 pedicles were broken of greater than 4mm, 1 at T2 and 1 at T4, with serious spinal cord compression. The external wall of 1 pedicle was broken at T2. Conclusions： The ATPS techniques at T1, T2 and the ARTPS techniques at T3, T4 are feasible, but the safety and clinical practice and further research is needed.