Vascular anatomy anterior to lumbosacral transitional vertebrae and implications for anterior lumbar interbody fusion.
BACKGROUND CONTEXT: Anterior approaches to the lumbosacral spine afford the ideal window to the disc for interbody fusion. Vascular injuries represent the most feared complications of such approaches. Unfortunately, the combination of more procedures being performed, more surgeons at the beginning of the learning curve and less invasive techniques of approach combine to increase the risk of vascular injury in the face of altered vascular anatomy. PURPOSE: To assess cases in which vascular anatomy significantly altered the surgical approach to the lumbosacral junction. STUDY DESIGN/SETTING: Chart review of operative reports. PATIENT SAMPLE: All patients undergoing anterior lumbar interbody fusion between 1994 and 1997 at one large center. METHODS: We reviewed all cases of anterior lumbar interbody fusion performed between 1994 and 1997 to discover cases requiring significant alteration in approach because of vascular variation. RESULTS: One hundred seven consecutive cases were reviewed. Of these, 11 required significant alteration of the approach secondary to vascular variation. All 11 were in cases at the functional lumbosacral junction above a fixed transitional level. In only one case of transition was a usual approach able to be used. CONCLUSIONS: A consistent pattern of altered vascular anatomy anterior to the functional lumbosacral junction was found. This pattern is depicted and the surgical alterations required discussed. Such alteration in surgical approach was required in nearly all cases with transitional vertebrae and represented about 10% of cases overall. If anterior lumbar surgery is to be performed at the functional lumbosacral junction in the presence of transitional vertebrae, it is vital that close attention be paid to the vascular anatomy and more open techniques of approach should be considered.