Spondylolysis (Pars Stress Fracture)

What it is

Spondylolysis is a stress fracture in a small bridge of bone called the pars interarticularis, which connects parts of a vertebra. It most often develops in the lowest level of the back (L5) during the active years of youth, especially in athletes whose sports involve a lot of arching and twisting — gymnastics, dance, football, and similar. Unlike a spondylolisthesis, here the bone has a crack but the vertebra has not slipped.

What it feels like

The usual symptom is low back pain that is worse with activity — particularly arching backward — and better with rest. In a young athlete, persistent activity-related back pain that does not settle is the pattern that makes me look for this. Many people, though, have a pars defect and never know it, because it causes no symptoms.

How we diagnose it

X-rays may show the defect, but a fresh stress fracture is often seen best on more detailed imaging such as a CT or MRI, which can also tell whether the fracture is recent (and therefore has healing potential) or old. Matching the imaging to your activity-related pain is what confirms it.

How we treat it

The great majority is treated without surgery. A period of rest from the aggravating sport, a structured physical therapy program for core and hamstring flexibility, and sometimes a brace allow many fresh stress fractures to calm down or heal, after which athletes usually return to their sport. Surgery is reserved for the minority with pain that persists despite good non-surgical care — and when it is needed, repairing the pars directly can sometimes fix the problem while preserving the motion of that level.

The science — for the curious

Two things shape the outlook: whether the fracture is recent, and whether it stays put. A fresh stress fracture in a young person has real potential to heal with rest, which is why early recognition matters. An older, established defect may not knit but is often perfectly stable and pain-free. The reason I follow it is to be sure it does not progress to a slip over time — most do not — and to keep treatment focused on returning you to activity safely.

Learn more

OrthoInfo — Spondylolysis and Spondylolisthesis: orthoinfo.aaos.org

OrthoInfo — Low Back Pain: orthoinfo.aaos.org

This handout is general education about a common condition and does not replace the personalized advice we discuss in clinic. If anything here does not match what we talked about, what we talked about wins — please ask me.