Often known as lumbar spondylolysis, for many people an acute pars inter-articularis injury is a major cause of lower back pain—particularly for children—and is most often seen in athletes.

Acute pars inter-articularis injury occurs when the inter-articularis—an arched portion of the vertebra connecting the facet joints—is damaged. Whereas some consider it an outright fracture of the vertebra, the injury actually occurs when undue strain is placed on the ligaments and the vertebral bones. In this sense it is more of a stress fracture or weakness of this segment of bone.

It’s estimated that acute pars inter-articularis injuries are found in six out of every 100 people, most of who acquire the condition through athletic activity. Furthermore, the injury occurs most commonly at the fourth of fifth lumbar vertebra (L4 and L5).

For many sufferers, the symptoms may lie dormant for a long time. But for those who do have symptoms, pain in the lower back is the most common. Additionally, this pain can move into the lowers legs and buttocks, and may get worse with physical activity and better when the body is at rest.

This condition is diagnosed by a thorough clinical history combined with imaging, most commonly x-rays, CT scans and MRIs, all of which can determine the extent of the injury. One-fifth of “defects” appear during an x-ray, which can also determine whether spondylolisthesis—a dislocation of the vertebra in a forward direction—is occurring.

Simple over-the-counter pain medications can be very helpful during the onset of symptoms, however non-steroidal anti-inflammatory drugs are not recommended as they may impede healing. Once pain is under control, physical therapy to enhance blood flow and bone tissue healing may be necessary. In some cases where patients are experiencing tremendous pain and potential nerve damage, surgical treatment may be required for relief.