Abstract：Objective To radiographically analyze the relationships of the nerve root and the safe trajectory in lumbar using percutaneous transforaminal endoscopic discectomy (PTED) approach.Methods A retrospective study from January 2011 to January 2015 in Tianjin Hospital was carried out. One hundred MRIs of transverse views and 100 X-rays were used for image analysis, those with previous spinal surgery, trauma or gross deformity were omitted from the study. The MRI study was done bilaterally from L2/3 to L5/S1. On transverse MRI, the foraminal width (G), the nerve root-disc distance (H), nerve root-facet distance (I) and the target angle (J°) were analyzed at the superior (s) and inferior (i) margin of the disc. The X-ray study was done from L4/5 to L5/S1 in two planes AP (a) and Lateral (b). The crest height (Q) and target angle (R°) were measured on both planes.Results On transverse MRIs, the foraminal width was larger at superior margin of the disc. The smallest Gi was measured at the inferior margin of L4/5 [(2.72±1.40) mm] and the largest Gs was measured at the superior margin of L2/3 [(5.16±1.53) mm]. The nerve root-disc distance decreased caudally and was measured closer at the inferior margin of the disc. The nerve root lay dorsal to the disc at L2/3 and at L3/4, whereas the nerve root lay ventral to the disc at L4/5 and L5/S1. The nerve root-facet distance was measured shortest at the superior margin than at the inferior margin of the disc. The shortest Is of superior margin was at L4/5 [(-2.55±4.94) mm] and the longest Ii of inferior margin at L5/S1 [(-8.23±11.11) mm]. The target angles (Js, Ji) decreased caudally. The target angles at L2/3 and L3/4 were wider at their superior margin than their inferior margin. In contrast, the angles at the lower lumbar levels, L4/5 and L5/S1, were smaller at their superior margin than those at their inferior margin. On X-rays, L4/5 lied almost at the same level of the iliac crest whereas L5/S1 lay below. The target angle (Ra°,Rb°) at L5/S1 was much steeper than that at L4/5.Conclusions At the lower lumbar levels (L4/5, L5/S1) the foraminal width decreases, the nerve root lies more ventrally to the disc and the trajectory angle is too narrow or steep. During transforaminal percutaneous endoscopic lumbar discectomy these features put the exiting nerve root at risks of iatrogenic injury. On that account, for reasons aforementioned, it is highly advised to enlarge the foramen to achieve adequate access to a safer passage of endoscopic instruments and thus to minimize the risks of nerve injury.
徐宝山, Yuvraj Hurday, 杜立龙, 郭林, 曹毅, 万业达. 经皮椎间孔镜手术入路的X线、MRI分析[J]. 中华解剖与临床杂志, 2015, 20(6): 483-487.
Xu Baoshan, Yuvraj Hurday, Du Lilong, Guo Lin, Cao Yi, Wan Yeda.. X-ray and MRI analysis of the percutaneous transforaminal endoscopic approach. Chinese Journal of Anatomy and Clinics, 2015, 20(6): 483-487.
Yorimitsu E, Chiba K, Toyama Y, et al. Long-term outcomes of standard discectomy for lumbar disc herniation: a follow-up study of more than 10 years[J]. Spine(Phila Pa 1976), 2001, 26(6): 652-657.
Suk KS, Lee HM, Moon SH, et al. Recurrent lumbar disc herniation: results of operative management[J]. Spine(Phila Pa 1976), 2001, 26(6): 672-676.
[4]
Nellensteijn J, Ostelo R, Bartels R, et al. Transforaminal endoscopic surgery for symptomatic lumbar disc herniations: a systematic review of the literature[J]. Eur Spine J, 2010, 19(2): 181-204.
Schubert M, Hoogland T. Endoscopic transforaminal nucleotomy with foraminoplasty for lumbar disk herniation[J]. Oper Orthop Traumato, 2005, 17(6): 641-661.
[7]
Hirano Y, Mizuno J, Takeda M, et al. Percutaneous endoscopic lumbar discectomy-early clinical experience[J]. Neurol Med Chir(Tokyo), 2012, 52(9): 625-630.
[8]
Torun F, Dolgun H, Tuna H, et al. Morphometric analysis of the roots and neural foramina of the lumbar vertebrae[J]. Surg Neurol, 2006, 66(2): 148-151.
[9]
Choi I, Ahn JO, So WS, et al. Exiting root injury in transforaminal endoscopic discectomy: preoperative image considerations for safety[J]. Eur Spine J, 2013, 22(11): 2481-2487.
[10]
Xin G, Shi-Sheng H, Hai-Long Z. Morphometric analysis of the YESS and TESSYS techniques of percutaneous transforaminal endoscopic lumbar discectomy[J]. Clin Anat, 2013, 26(6): 728-734.
[11]
Arslan M, Cmert A, Aar HI, et al. Nerve root to lumbar disc relationships at the intervertebral foramen from a surgical viewpoint: An anatomical study[J]. Clin Anat, 2012, 25(2): 218-223.
[12]
Mirkovic SR, Schwartz DG, Glazier KD. Anatomic considerations in lumbar posterolateral percutaneous procedures[J]. Spine(Phila Pa 1976), 1995, 20(18): 1965-1971.
[13]
Ahn Y. Transforaminal percutaneous endoscopic lumbar discectomy: technical tips to prevent complications[J]. Expert Rev Med Devices, 2012, 9(4): 361-366.
[14]
Telfeian AE. Endoscopic transforaminal discectomy for an extruded lumbar disc herniation[J]. Pain Physician, 2013, 16(1): E31-E35.
[15]
Hoogland T, van den Brekel-Dijkstra K, Schubert M, et al. Endoscopic transforaminal discectomy for recurrent lumbar disc herniation: a prospective, cohort evaluation of 262 consecutive cases[J]. Spine(Phila Pa 1976), 2008, 33(9): 973-978.
[16]
Birkenmaier C, Chiu J, Fontanella A. Guidelines for endoscopic spinal surgery[C]. International Society for Minimal Intervention in Spinal Surgery (ISMISS), 2008.
[17]
Civelek E, Solmaz I, Cansever T, et al. Radiological analysis of the triangular working zone during transforaminal endoscopic lumbar discectomy[J]. Asian Spine J, 2012, 6(2): 98-104.
[18]
Choi KC, Kim JS, Ryn KS, et al. Percutaneous endoscopic lumbar discectomy for L5-S1 disc herniation: transforaminal versus interlaminar approach[J]. Pain Physician, 2013, 16(6): 547-556.
2015, Vol. 20 
