At which spinal level is spondylolysis and spondylolisthesis most commonly found?

Spondylolysis and spondylolisthesis are conditions involving the lumbar spine, particularly at the lower levels where the biomechanical demands are highest. The most common site for these conditions is at the fifth lumbar vertebra (L5).

Spondylolysis is a defect or fracture in the pars interarticularis of the vertebra and is often associated with repetitive stress or trauma, especially in athletes involved in sports that require hyperextension of the back. Since L5 is subjected to considerable forces, especially during activities that involve bending or twisting, it's particularly vulnerable to these conditions.

Spondylolisthesis refers to the forward slippage of one vertebra over another, and it often occurs in conjunction with spondylolysis when the structural integrity is compromised. The L5-S1 segment, where the fifth lumbar vertebra meets the sacrum, is also a common site where this slippage manifests, leading to mechanical instability and associated symptoms.

While spondylolysis can occur at other levels of the lumbar spine and even the thoracic region, L5 is by far the most prevalent location for both spondylolysis and spondylolisthesis due to the reasons mentioned regarding stress,