What condition describes the body of L5 slipping forward on top of S1?

The condition where the body of the fifth lumbar vertebra (L5) slips forward over the first sacral vertebra (S1) is known as spondylolisthesis. This condition typically occurs due to a defect in the vertebrae that allows for forward slipping, which can lead to pain and neurological symptoms depending on the severity and any nerve involvement.

Spondylolisthesis often results from factors such as degeneration of the disc and joints, trauma, or a congenital defect. It is characterized by the misalignment of vertebrae, reducing stability and potentially compressing nearby nerves. As the vertebrae shift, the alignment of the spine is altered, which can have implications on posture and spinal health.

In contrast, scoliosis refers to a lateral curvature of the spine, lordosis involves an exaggerated inward curve of the lumbar spine, and kyphosis describes an excessive outward curve of the thoracic spine. Each of these conditions affects the spine differently compared to the forward slipping seen in spondylolisthesis.