What is it?

The spine is made up of a column of connected bones called vertebrae. The pars interarticularis (abbreviated “pars”) is a region of bone that links one vertebral segment to an adjacent vertebral segment.

An injury to the pars is called “spondylolysis”. It typically occurs in the lumbar spine and can occur on either or both sides. The severity ranges from a stress reaction (“bone inflammation”) to a displaced fracture.


What causes it?

Spondylolysis often occurs in adolescent athletes that do a significant amount of backward bending through the low back (especially football, gymnastics, wrestling, soccer and dancing) due to rapid growth of bone being more susceptible to shearing injury.

It can occur as a result of a single major injury, or be due to multiple minor injuries.


What are the signs and symptoms?

Spondylolysis causes low back pain. There may also be pain or stiffness involving the buttock or hamstring.

The pain may be mild and intermittent, and initially thought to be a simple back strain. However, if the pain does not resolve within a few days, an adolescent needs to be evaluated by a physician, as this condition is a very common cause of low back pain at this age.

It is not uncommon for the pain to improve or resolve, despite inadequate healing of a fracture.


What are the other side-effects/areas of the anatomy affected?

If it is not treated early enough, the severity of the injury can worsen. For example, a “bone bruise” can turn into a displaced fracture, or a one-sided injury can lead to injury on the other side.

If these fractures are not treated early enough, their healing potential significantly lessens. A fracture that could have healed with simple rest from activities sufficient for bone healing, may instead require a much longer period of rest, use of a back brace, or, rarely, surgery.

Unhealed fractures, especially if present on both side of the spine, leaves the back much more susceptible to further injury, and can lead to permanent symptoms and require long term treatment.

Unhealed fractures can cause chronic pain due to spinal instability. Instability can rapidly worsen, or slowly worsen over decades, and cause secondary conditions and symptoms.

The back pain can worsen if joint pain or cysts develop, or the intervertebral disc degenerates.

Spondylolisthesis is a term that describes one spinal level slipping forward or backward on an adjacent level, which may lead to spine pain or sciatica (e.g. leg pain, numbness, tingling, and/or weakness) due to pinched nerves in the spinal canal.


How is it diagnosed?

A physician will first perform a thorough medical history and physical examination. An individual will often have worsened back pain with back-bending or standing only on the leg of the affected side.

X-rays may be obtained, but it is important to know that an x-ray cannot exclude this condition. MRI can be a good test, but CT and bone scans may be necessary.


What are the treatment options?

It is imperative that a young person with back pain not return to sports or injury-prone activities.

Any young person with significant low back pain, pain that does not resolve within a few days, or back pain that radiates down a leg needs to be evaluated by a physician with knowledge of back pain in children and adolescents.

Anyone with leg numbness, leg weakness, or abnormal bowel or bladder function needs to seek care urgently.

Treatment depends on the degree of the injury. Rest from all physical activity is mandatory until the injury has healed. Back bracing may be necessary.

Medications can help with pain control, but masking pain to participate in sports is not advised.

After an adequate period of rest, a gradual return to activities is advised, utilizing physical therapy and athletic trainers.

Any “setbacks” in pain or stiffness requires re-evaluation by the physician. Only a physician should clear an athlete to return to sports after this injury.