MORPHOMETRIC ANALYSIS OF THE SURGICAL CORRIDOR IN THE PRE-PSOAS APPROACH: AN MRI STUDY IN THE BRAZILIAN POPULATION

ABSTRACT Objective: This study aims to perform a morphometric analysis and explore the characteristics of the surgical corridor of the anterior to psoas approach in the Brazilian population through magnetic resonance imaging (MRI). Methods: Two hundred spinal MRI scans of patients aged between 18 and 80 years were evaluated using axial cuts at L2-L5 levels and a sagittal cut, T2 weighted. The relationship between the left psoas muscle and the abdominal aorta or the left common iliac artery was analyzed. The anterior to psoas corridor was defined as the shortest distance between the posterolateral aspect of the aorta or inferior vena cava or the nearest iliac vessel and the anteromedial aspect of the ipsilateral psoas muscle. Results: 104 females and 96 males with a mean age of 49,68±2.04 (range 18–80) years. The mean anterior to psoas distance at the L2-L3 level was 14,17±0.75mm; at the L3-L4 level was 12,08±0.77m,m and at the L4-L5 level was 9,12±0.77mm. The surgical corridors at all levels were larger in the older population. Conclusion: In most Brazilian patients, the anterior to psoas approach can be a good alternative for lumbar intervertebral fusions. As a routine in preoperative examination and surgical planning, lumbar MRI is fundamental in preoperative evaluation for anterior to psoas approach surgery. Level of Evidence IV; Descriptive study.