Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

The most common location for spondylolisthesis is at the L5/S1 level. This area is particularly susceptible to this condition due to a combination of factors including the anatomical characteristics of the lumbar spine and the biomechanical stresses placed on this segment. The L5/S1 vertebrae interface is subjected to significant load and shear forces, especially during activities that involve flexion and extension of the lumbar spine.

In addition, the sacrum's fixed nature creates a predisposition for L5 to slip anteriorly over S1, particularly in individuals who may have inherent weaknesses, such as those with spondylolysis (a defect in the pars interarticularis). This condition can be exacerbated by factors such as sports or activities that involve repetitive stress to the lower back, leading to increased incidence of spondylolisthesis at this level compared to other lumbar vertebrae.

While spondylolisthesis can occur at L3/L4, L4/L5, and L2/L3, these levels do not experience the same combination of shear forces and structural weaknesses as L5/S1, making it the most commonly affected site.