Pars Defect (Spondylolysis)

What is a pars defect?

A pars defect — also called spondylolysis — is a stress fracture in a specific small bridge of bone in the lumbar spine called the pars interarticularis. It's most commonly seen in adolescents whose sport involves repeated extension or twisting of the lower back: gymnasts, dancers, fast bowlers, divers.

The fracture develops gradually from repeated overload rather than a single injury. Many young athletes are surprised to be diagnosed because there hasn't been a specific moment they associate with the problem.

Pars defects can heal completely if caught early, particularly in younger children. Older adolescents and adults may have a longer journey to full recovery, but the vast majority do well with the right management.

What does it feel like?

Lower back pain is the main symptom. Common features include:

• Pain in the lower back, often on one side

• Pain made worse by extending the back (arching backwards)

• Pain during or after sport, particularly extension-heavy activities

• Stiffness that's worse first thing in the morning

• Pain that improves with rest but returns with activity

Some children develop tightness in the hamstrings as a protective response, which can make the picture more complex. Symptoms may have been present for weeks or months before assessment.

How is it diagnosed?

Examination raises the suspicion when there's pain on extension and the right pattern of symptoms. Imaging is essential to confirm the diagnosis and assess the activity of the fracture.

MRI is the most useful imaging in adolescents — it shows whether the fracture is active and likely to heal. CT scanning provides detailed bone images and can be useful in specific situations. X-rays may show established defects but miss earlier ones.

It's important to identify whether one or both sides of the spine are involved, and whether there's any associated slip of one vertebra on another (spondylolisthesis), as this changes the management.

What are the treatment options?

Most pars defects are managed without surgery. The mainstay is a period of relative rest from the aggravating sport, structured rehabilitation focusing on core stability and back strength, and gradual return to activity. Bracing is sometimes used in active fractures to support healing.

Surgery is reserved for the small number of cases where pain persists despite thorough conservative management, or where there are specific structural concerns. Whether surgery is right in your child's case is something Nev will work through with you at your consultation.

When should you get it checked?

Seek a specialist assessment if:

• Your child has lower back pain that's affecting their sport

• Pain is consistently worse with activities that extend the back

• Symptoms have persisted for more than a few weeks

• You've been told there's a stress fracture and want a clear plan

• Your child is being held back from sport without a clear explanation

Pars defects respond best to early, structured management. The longer they're left without proper assessment, the more difficult the recovery can become.