Laparoscopic anterior lumbar interbody fusion at L4-L5: an anatomic evaluation and approach classification.
METHODS
An anatomic classification system was devised on the basis of operative reports and preoperative magnetic resonance imaging or computerized tomography from 139 patients who underwent laparoscopic anterior lumbar interbody fusion involving L4-L5.


OBJECTIVE
To devise a classification system for laparoscopic exposure of the L4-L5 disc space that would allow prediction of the safest approach for any given vascular configuration.


BACKGROUND
The laparoscopic technique has gained acceptance at L5-S1 but has been less successful at L4-L5. The vascular bifurcation and the variability of the anatomy have led to difficulties with exposure.


METHODS
Data were collected on 139 patients undergoing laparoscopic anterior lumbar interbody fusion involving the L4-L5 disc space. Operative notes and preoperative magnetic resonance imaging and computed tomography scans were reviewed, and a classification system was devised based on the aortic bifurcation and confluence of the left iliac vein with the vena cava. Three variations were identified. Complications, particularly ejaculatory dysfunction, were described.


RESULTS
Three classification categories were described. Twenty-five patients (18%) were classified as category A (above the bifurcation of both vessels), 52 patients (37%) were classified as category B (below the bifurcation of both vessels), and 51 patients (37%) were classified as category C (between the left iliac artery and vein). There were 8 (5.8%) intraoperative and 17 (12.2%) postoperative complications. Ejaculatory dysfunction constituted the majority of the postoperative complications, representing 16% of the male population. The incidence of ejaculatory dysfunction correlated with exposure from the left side of the aorta or the left iliac artery. For two-level fusions from L4 to S1, the incidence of ejaculatory dysfunction was 63% for category A but 0% for categories B and C. An alternative approach was suggested for category A: exposing the disc space between the aorta and vena cava.


CONCLUSIONS
The laparoscopic approach to L4-L5 is complicated by the variability of the vascular anatomy encountered during the exposure. Routine magnetic resonance imaging or computed tomography can be used to classify the vascular anatomy and plan the optimal approach. Avoiding the left side of the aorta or the left iliac artery may minimize the risk of ejaculatory dysfunction.
New Hampshire Spine Institute, Bedford, New Hampshire 03110, USA. tkleeman@nhspine.com
Thomas J
TJ
Kleeman
Uri
U
Michael Ahn
William B
WB
Clutterbuck
Connie J
CJ
Campbell
Anne
A
Talbot-Kleeman
D001012:Aorta, Abdominal / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D004617:Embolism / Q000209:etiology; D007172:Erectile Dysfunction / Q000209:etiology / Q000517:prevention & control; D005260:Female; D006801:Humans; D007084:Iliac Vein / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D007431:Intraoperative Complications / Q000517:prevention & control; D010535:Laparoscopy / Q000009:adverse effects / Q000379:methods*; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D008161:Lumbosacral Region / Q000033:anatomy & histology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008488:Medical Illustration; D018579:Patient Selection; D011183:Postoperative Complications / Q000517:prevention & control; D011446:Prospective Studies; D012189:Retrospective Studies; D018570:Risk Assessment; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D013131:Spine / Q000033:anatomy & histology* / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D014682:Vena Cava, Inferior / Q000033:anatomy & histology / Q000000981:diagnostic imaging