Risk Management for Avoidance of Major Vascular Injury due to Lateral Transpsoas Approach.

STUDY DESIGN A retrospective study using 323 contrast-enhanced, multi-planner three-dimensional computed (3D-CT) scans. OBJECTIVE The aim of this study was to identify risk factors for injury to the major vessels in the lateral transpsoas approach. SUMMARY OF BACKGROUND DATA To avoid critical complications such as major vessel injury, it is essential to examine anatomical information related to preoperative risk management that is specific to the lateral transpsoas approach. METHODS The abdominal contrast-enhanced, multi-planner 3D-CT scans of 323 consecutive subjects (203 males and 120 females, 15-89 years old) were retrospectively reviewed. The true axial views were used for evaluation of the locations of the major vein and artery at L3 to L4 and L4 to L5. According to the Moro system, the axial view was divided into 6 zones from the front side (A, I II, III, IV, P) and the locations of the dorsal tangential line of the major vessels were evaluated. RESULTS At the L3 to L4 level, the dorsal tangential line of the major vein located in zone A was found in 18% of subjects, in zone I in 74%, and in zone II in 8%. The line of the major artery was located in zone A in 92.6% of subjects and in zone I in 7.1%. At the L4 to L5 level, the line of the major vein was located in zone A in 5% of subjects, in zone I in 75%, in zone II in 20%, and in zone III in only 1 subject. The line of the major artery was identified in zone A in 87% of subjects, in zone I in 12%, and in zone II in 1%. Women had significant dorsal-migrated veins and arteries at both spinal levels (P < 0.01). CONCLUSION To avoid critical complications in extreme lateral lumbar interbody fusion, careful preoperative radiological evaluation of the major vessels and intraoperative care are important. LEVEL OF EVIDENCE 3.