THE ANATOMIC VARIATIONS OF MAJOR ABDOMINAL VESSELS; THE CASE FOR PREOPERATIVE 3D CT ANGIOGRAPHY IN DISC ARTHROPLASTY SURGERY

Abstract

Background: The recent significant surge in disc arthroplasty surgery has popularised the minimally invasive anterior approach to access the target disc. However, as the abdomen and its great vessels are not the natural territory for the spinal or neurosurgeon, extra care must be taken to access the disc whilst still minimising the risk of the not too uncommon vascular injury. Three dimensional CT angiography has been routinely used in this centre as part of pre operative planning of disc surgery. This was prompted by the frequent intraoperative observation that the vascular pattern has often been far from consistent.

Aim of Study: To assess the anatomic variations of the major abdominal vessels.

Methods: The pre operative 3D CT angiograms of eighty nine patients who had lumbar disc replacements were examined studying specific vascular anatomic parameters.

Parameters studied included position of the Aorta and Inferior Vena Cava, the levels and angles of their bifurcation and the all too important ascending lumbar vein. We also commented on the most accessible (visible) disc part in relation to surrounding vessels.

Results: We found significant variations in vessels anatomy in all parameters studied, confirming inconsistency of the abdominal vasculature. In particular, the angio-grams suggested an alternative approach to access the L4/5 disc in 30% of cases.

Discussion: The incidence of vascular complications in disc arthroplasty surgery is reported to be around 3%. This includes laceration particularly to the left common iliac vein, thrombosis, both arterial and venous and intimal tears. Most of these complications are more than often the result of excessive traction and failure to adequately visualise and mobilise the vessels. Pre operative imaging is therefore critical to plan best vascular approach to the disc. Although MRI scanning is useful in assessing the vasculature, it is less superior to 3D CT angiograms in delineating vessels topographic relation to vertebra and disc.

Conclusion: We have noticed significant variations in abdominal vasculature anatomy. This may have a direct influence on access to L4/5 and higher discs in a siginificant number of cases.