Anatomic study of minimally invasive lateral thoracolumbar approach in treatment of fractures

Objective To explore the working zones in minimally invasive lateral thoracolumbar(T11-L2) approach,so as to provide anatomical evidence for the treatment of special types of fractures.Methods Totally 21 adult cadaveric specimens(11 males and 10 females) were enrolled in this study.Kirschner wires were used to simulate the minimally invasive needles and inserted into the superior endplate,center,inferior endplate and adjacent discs of T11-L2 along the lateral midline of the spine.The 4 puncture points of every segment were labeled as A,B,C,and D,respectively.The distribution of vessels and nerves on the lateral side of thoracolumbar spine were observed.And the working zones on the lateral side of T11-L2 were measured.The best puncture point of minimally invasive device was finally determined.Results On the lateral side of vertebral body,safe window,a working zone,was composed of the upper and lower edge of the vertebral body,sympathetic trunk,the posterior edge of the vertebral body or lumbar plexus after ligating segmental vessels.The safe window increased gradually from T11 to L2:(273.35±69.72) mm2,(409.59±74.24) mm2,(555.78±139.74) mm2,and(614.36±89.46) mm2 in males;(173.39±46.62) mm2,(289.51±49.72) mm2,(400.85±45.44) mm2,and(451.44±59.80) mm2 in females.Point at the superior 1/2 region of the lateral vertebra was taken as the best puncture site in the minimally invasive thoracolumbar approach.Conclusion It is anatomically feasible to treat the special type of Denis B burst fracture by minimally invasive lateral approach at the superior 1/2 site near the end plate of T11-L2,anterolateral decompression and vertebral reconstruction in the safe window.