Spondylolysis (spon-duh-LOL-uh-sis) is a defect of a narrow piece of bone (the pars interarticularis) in the vertebra. More to Know The human spine is made up of 33 vertebrae — nine are fused together to form the tailbone (coccyx), and the other 24 are in the back. The lumbar vertebrae are in the lower back and closest to the tailbone, which is commonly where spondylolysis occurs. Each vertebra has a ring of bone that forms part of the spinal canal. There are two narrow bridges of the ring called the pars interarticulari. Injuries or overuse can cause a fracture in this part of the vertebra, which can lead to persistent lower back pain. Spondylolysis is more commonly seen in teens who overtrain in sports that can strain the lower back, like football, weightlifting, gymnastics, and wrestling. Keep in Mind If it's not allowed to heal properly, spondylolysis can lead to chronic back pain, loss in flexibility, and a painful condition called spondylolisthesis, which is when the vertebra slips out of place. Most cases of spondylolysis heal just fine when diagnosed and treated early with rest, proper exercise that does not strain the lower back, and medication to help reduce the swelling. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles Sports Medicine Center Get tips on everything from finding the best sport for your kids to preventing and handling injuries. Read More Safety Tips: Football Football is a lot of fun, but since the name of the game is to hit somebody, injuries are common. To keep things as safe as possible, follow these tips. Read More Safety Tips: Gymnastics Gymnastics is a great sport and a fun way to get a muscular, toned body. But, it also presents a very real risk of injury. To keep things safe during practice and competition, follow these tips. Read More Kyphosis Your spine, or backbone, normally curves forward gently as it runs up your back. Sometimes, though, someone's back can be rounded too far forward, which is a condition known as kyphosis. Read More Magnetic Resonance Imaging (MRI): Lumbar Spine A lumbar spine MRI is a painless test that uses a magnetic field and radio waves to produce detailed pictures of the bones, disks, and other structures in the lower back. Read More Scoliosis Scoliosis makes a person’s spine curve from side to side. Large curves can cause health problems like pain or breathing trouble. Health care providers treat scoliosis with back braces or surgery when needed. Read More Kyphosis Everyone's spine is slightly rounded forward at a gentle angle. If this angle is too pronounced, more than 50 degrees or so, it's called kyphosis, also known as roundback or hunchback. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.