Definition: Spondylolysis is a word that is used to describe a condition where there is a defect in the pars interarticularis of the spine; this most often occurs in the lumbar region.
Spondylolysis can be asymptomatic, and can be quite painful. When the condition is bilateral (occurs on both sides of the spine) it is called spondylolisthesis. In this condition, a given vertebral body can "slip" forward over the vertebrae directly below. As the condition worsens, patients typically complain of pain in the low back, and sometimes radiating down the thighs. Treatment begins usually with back strengthening, but may necessitate a back brace or even surgery.
