Two level Anterior Lumbar Interbody Fusion (ALIF) in a patient with a rare vascular malformation, a duplication of the inferior vena cava

Venous Anomalies Complicating Anterior Lumbar Interbody Fusion Exposures

The effects of anomalous vasculature impeding optimal exposure to an anterior lumbar interbody fusion approach are limited in literature. We present five individual, unique cases of vascular anomalies in patients undergoing two-stage anterior-posterior lumbar interbody fusion. Cases 1, 2, 4, and 5 have yet to be described in literature in context of anterior lumbar interbody fusions. Case 3 presents anomalous vasculature that has only been described in two other case reports. Case 1 presents the right internal iliac vein originating from the left common iliac vein which was transected for L4-L5 vertebral disc exposure. Case 2 presents the left internal iliac vein originating from the right common iliac vein which required an oblique approach. Case 3 presents a duplicated inferior vena cava that was taken into account but did not interfere with the anterior retroperitoneal approach. Case 4 presents large osteophytes adhering to the left common iliac vein which limited safe dissection and mobilization. Case 5 presents the left internal iliac vein with a high takeoff spanning across the L5-S1 vertebral disc space and requiring transection. This case series highlights the need for preoperative imaging and a working detailed knowledge of anatomy to avoid damaging vasculature that can potentially lead to fatal consequences. The information given in this case series should inform both spine and vascular surgeons on proper preoperative planning. To maximize operative efficiency and safety, spine surgeons and vascular surgeons should collaborate to minimize surgical complications.

Risk Assessment of Anterior Lumbar Interbody Fusion Access in Degenerative Spinal Conditions

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

Develop an evidence-based preoperative risk assessment scoring system for patients undergoing anterior lumbar interbody fusion (ALIF).

SUMMARY OF BACKGROUND DATA

ALIF may hold advantages over other fusion techniques in sagittal restoration and fusion rates, though it introduces unique risks to vascular and abdominal structures and thus possibly increased risk of operative morbidity.

METHODS

Primary, 1 or 2-level ALIFs were identified in a surgical registry. Baseline characteristics were recorded. Axial magnetic resonance imagings at L4-L5 and L5-S1 were reviewed for vascular confluence/bifurcation or anomalous structures, and measured for operative window size/slope. To assess favorable outcomes, a clinical grade was calculated: (clinical grade=blood loss×operative duration), higher value indicating poorer outcome. To establish a risk scoring system, a base risk score algorithm was established and stratified into 5 categories: high, high to intermediate, intermediate, intermediate to low, and low. Modifiers to base risk score included age, body mass index, operative level, history of bone morphogenic protein use, calcified vasculature, spondylolisthesis grade, working window size and slope, and abnormal vasculature. Modifiers were weighted for contribution to surgical risk. A total risk score was calculated and evaluated for strength of association with clinical outcome grades by Pearson correlation coefficient.

RESULTS

A total of 65 patients were included. Mean clinical outcome grade was 5.6, mean total risk score 21.3±21.5. Multilevel procedures (L4-S1) mean total risk score was 57.3±7.8. L4-L5 mean total risk score was 23.6±5.2; L5-S1 mean total risk score 8.3±6.6. Correlation analysis demonstrated a significant and strong relationship (| r |=0.753; P <0.001) between total risk scores and clinical outcome grades.

CONCLUSION

Calculated ALIF risk scores significantly correlated with operative duration and blood loss. This scoring system represents a potential framework to facilitate clinical decision-making and risk assessment for potential ALIF candidates with degenerative spinal pathologies.