Cadaveric Vascular Anatomy for Total En Bloc Spondylectomy in Malignant Vertebral Tumors

Study Design The authors studied the vascular anatomy of the thoracic and lumbar spine in cadavers related to the clinical use of total en bloc spondylectomy in malignent vertebral tumors. Objective To enhance anatomic knowledge on major and associated segmental vessels surrounding the anterior vertebral column of the thoracic and lumbar spine. Summary of Background Data No reports have, to the authors' knowledge, referred clinically to the anatomic relationship between the vascular system and the anterior vertebral column in performing posterior total en bloc spondylectomy on the thoracic and lumbar spine. Methods The authors studied the major vessels, segmental arteries and veins, and tendinous portions of the lumbar diaphragm inserting onto the vertebrae in 21 cadavers to view the vascular system surrounding the anterior vertebral column in the thoracic and lumbar spine. Results The aorta descended in direct contact with the anterior vertebral column below T4 or T5 and branched into two common iliac arteries at L3 in one cadaver, at L3-L4 in two, at L4 in eight, at L4-L5 in nine, and at L5 in one. The uppermost intercostal artery originated at T4 or T5, and 48 (14%) variations in 348 intercostal arteries did not originate from the thoracic aorta. Two common iliac veins became confluent at L3-L4 in one subject, at L4-L5 in 13, and at L5 in seven. The inferior vena cava ascended in tight contact with the vertebral column and entered into the vena caval foramen of the diaphragm anterior to the right medial crus. The right medial crus of the diaphragm originated from the vertebra at L1-L2 in one subject, at L2 in two, at L2-L3 in 14, and at L3-L4 in four, whereas, on the left, this ligamentous origin located at L1-L2 in six, at L2 in two, at L2-L3 in 11, and at L3-L4 in two. The first two lumbar arteries ran consistently in the space between the medial crus and the vertebral column. Conclusions Total en bloc spondylectomy conducted posteriorly is less likely to damage the thoracic aorta from T1 to T4 but, distal to T5, the aorta must be carefully retracted anteriorly before manipulation of the affected vertebra(e). For a malignant tumor involving L1 or L2, the medial and, occasionally, the intermediate crura of the diaphragm and the first two lumbar arteries must be treated carefully before spondylectomy. Malignant tumors involving the L3 and L4 vertebral bodies can be approached with a total en bloc spondylectomy technique only when the inferior vena cava has been safely retracted anteriorly.