❓ What Is Lumbar Spondylolysis?

Lumbar spondylolysis is a stress fracture in the bony arch at the back of a lumbar vertebra (the pars interarticularis).
During the growth years the bones are not yet fully hardened, and repeated arching, twisting and jumping in sport can slowly create small cracks in that arch.
The fifth lumbar vertebra is by far the most common site (85–90% of cases). Among junior high school students who come in with low back pain, about 30–47% turn out to have lumbar spondylolysis.

⚙️ Why Does It Happen?

1

Repeated loading of the lower back

Jumping, arching backward and twisting day after day let tiny cracks build up in the bony arch

2

Growing bone is more fragile

While the growth plates are still open, the bone is more prone to stress fractures than adult bone

3

A crack forms in the bony arch

Early on it shows up on MRI as swelling inside the bone (bone marrow oedema); if it continues, the arch separates completely

4

Left untreated, it can progress to spondylolisthesis

If the vertebra slips forward, numbness in the leg or sciatica may appear

5

Finding it early is the key to bone healing

When it is diagnosed at an early stage, there is a good chance the bone will knit back together. At a later stage healing is still possible but less likely and takes longer, and in the final stage bone healing can no longer be expected

⚾ Baseball / Volleyball ⚽ Soccer / Track & Field 🤸 Gymnastics 📅 Junior high school years 📈 Growth spurt (ages 10–16)

🔍 Watch for These Symptoms

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Low back pain during or after sport

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Pain gets worse when arching the back

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A stiff lower back the day after practice

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Pain spreading into the buttock or back of the thigh

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Low back pain lasting more than two weeks should be checked — please come in rather than waiting

💊 Treatment (Early Diagnosis Matters)

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Early Diagnosis by MRI

MRI picks up the early swelling inside the bone that X-rays cannot show. We examine you with X-ray and ultrasound at the clinic and book the MRI at a partner hospital when it is needed. Finding it early matters for the chance of bone healing

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Rigid Brace

In early cases a hard brace is worn for 3–6 months to hold the lumbar spine steady and support bone healing

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Rest from Sport

Even once the pain eases, rest has to continue for the full period until the bone knits. For early-stage cases about 3 months is the usual guide

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Core Strengthening

Training the deep trunk muscles, mainly the transversus abdominis and multifidus, lowers the load on the lumbar spine

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Shockwave Therapy (ESWT)

We sometimes suggest this for stubborn cases. At our clinic it is self-pay (non-insured) care at 3,000 yen per session (tax included). Temporary pain, redness, swelling or bruising may occur at the treated site

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Gradual Return to Sport

Pool walking, then jogging, then sport-specific movements — step by step. Preventing a repeat injury is just as important

📈 Outlook & Recovery

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Found early, the bone has a good chance of healing

When MRI picks it up at an early stage, bone healing can be expected with around 3 months of conservative care, sometimes extended to about 6 months depending on how the bone is knitting. Even when the bone does not fully unite, around 90% of athletes treated conservatively have been reported to return to their sport, taking on average 4.6 months to get back.

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Watch for progression to spondylolisthesis
If the separation progresses and the vertebra slips forward, sciatica and numbness in the leg can appear, and some cases need surgery (spinal fusion). We do not perform surgery here, so we refer you to a partner hospital. Regular imaging follow-up is important.

👨‍👩‍👧 For Parents & Coaches

Lumbar Spondylolysis

Found early, the bone has a good chance of healing

💡 4 Things to Remember

🩻 Gotokuji Orthopedic Clinic