Anatomy Study For Posteiror-only Total En Bloc Spondylectomy In Lumbar Malignant Tumors

Objective: Through the simulation of surgery total en bloc spondylectomy on adultcadavers, to observe and measure the key parts of the local anatomy related to theclinical use of total en bloc spondylectomy in malignent vertebral tumors.Methods: The authors simulated the posterior-only total en bloc spondylectomysurgery for lumbar in12cadavers to study the following:①Length of posteriormidline incisions;②Distribution of lumbar segmental arteries outside the foramenarea;③The shortest distance between the lumbar accessory processes and thecorresponding nerve roots;④Regional anatomy of quadratus lumborum andintertransversarii muscles;⑤The area enclosed by the spinal nerves at L2/3、L3/4andthe distance of nerves roots retracted to the lateral at L2、L3;⑥Regional anatomy ofthe starting point of psoas and the width of the psoas retracted to the lateral at L3、L4;⑦The distance between lower edge of L4vertebra and the level of iliac crest peak;⑧Location of the crus of the diaphragm and distribution of segmental arteries alongvertebral fa ade;⑨Great vesselses around the lumbar spine and the width of the aortaand inferior vena cava pushed forward;⑩The median sagittal diameter, medianheight and median coronal diameter of the L3and L4vertebra.Results:①The incision length of standard lumbar TES surgery is ranges16.5～23.4cm, there is no significant statistical difference among L1, L2and L3(p>0.05), buteach one is different from the L4(p <0.05).②The shortest distance between thelumbar accessory processes and the corresponding nerve roots ranges13.48～22.48mm, both sides are no statistically significant difference(p>0.05).③The area enclosedby the spinal nerves ranges235.52～486.86mm~2at L3、290.66～551.23mm~2at L4,the distance of nerves roots retracted to the lateral ranges22.96～31.70mm at L2、23.63～35.22mm at L3, both sides are no statistically significant difference(p>0.05).④The width of the psoas retracted to the lateral ranges at34.59～40.59mm at L3、 32.23～41.92mm at L4，both sides are no statistically significant difference(p>0.05).⑤The lower edge of L4vertebra locates above the level of iliac crest peak in8cases(66.67%),below the level in4cases (33.33%).⑥Location of bilateral crus ofdiaphragm is not constant,19of24sides cover L1and L2segmental arteries whichtraveling beneath the crus of diaphragm.⑦The width of the aorta and inferior venacava pushed forward ranges12.68～30.15mm, The adjacent two segments has nostatistically significant difference(P>0.05), but there is statistically significantdifference between the non-adjacent segments(P<0.05);⑧The median sagittaldiameter and shortest median sagittal area are（26.49±2.82）mm and (524.27±51.46)mm~2at L3,（27.02±2.14）mm and (517.08±57.67) mm~2at L4.Conclusions:1. For a malignant neoplasm affecting L1or L2, it is necessary tocarefully separate the medial and occasionally intermediate crura of the diaphragmfollowed by ligation of the first two lumbar arteries and veins before isolation of theaffected vertebral body posteriorly.2. The area enclosed by spinal nerves is not large enough to roll out the lower lumbarwhole vertebral body, rough operation can cause nerve damage and dural tear, butafter plexus lumbalis dissection and psoas muscle retracted laterally, a safe space canbe acquired.3. The posterior-only total en bloc spondylectomy surgery is likely suit for L3andpart of L4malignant tumors in the circumstances of the lower edge locatesnecessarily above the level of iliac crest peak.