A pars defect of the lumbar spine refers to a stress fracture of the pars interarticularis, a small section of bone that joins the joints of the vertebrae in the back of the spine, according to OrthoInfo. Another name for the condition is spondylolysis, and it is common among young athletes who participate in sports such as football and gymnastics. The main symptom is lower back pain, which mimics a muscle strain.
A pars defect is most common at the lumbar vertebra number five, states the Hospital for Special Surgery. A pars defect in this region occurs because of repeated stress and strain to the vertebra. Gymnastics, karate, football and other activities that cause the frequent backwards bending of the spine increase the risk of developing the condition. The body responds to mild strain by producing more bone cells to strengthen the area. When stress occurs repeatedly or quickly, the body does not keep up, and a pars defect occurs.
A pars defect that affects both sides of the vertebra can lead to a vertebra sliding forwards, maintains the Hospital for Special Surgery. This condition, spondylolisthesis, sometimes causes back spasms, leg symptoms and posture changes. If severe nerve compression occurs, surgical treatment is an option.