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What is a pars defect?

Mr Nicholas Thomas explains all you need to know about pars defect.


A pars defect is a condition that affects the lower part of the spine (lumbar). It affects the pars interarticularis, which is a small segment of bone which joins the facet joint at the back of the spine. A pars defect means that the lower and upper portion of the spine bone (vertebrae) separate due to repeat stress and strain. This can happen unilateral (on one side) or bilateral (on both sides) of the spine. Although a pars defect can often be asymptomatic (without symptoms), it is the most common cause of lower back pain in adolescents (a majority of cases are found in 10-15 years olds). The defect mainly affects the lower part of the spine, specifically L5-S1 and L4-5.



If a pars defect is present it can lead to the patient suffering from other medical conditions such as stress fractures or spondylolisthesis. In some cases the upper vertebra slips forward relative to the lower one- this is spondylolisthesis. Neurological deficits are rare, with the more common symptoms being back pain and leg pain, which can result in a limited movement in the spine.


Possible cause of a pars defect:

The pressure on the pars interarticularis can cause the bone to break, which can be linked to activities that put stress or strain on the spine. This may include:

  • Gymnastics, athletics, diving due to hyperextension and/or extreme twisting.

  • Weight lifting, wrestling, tennis, dancing due to repetitive, forceful movements.

  • Pars defects can also be linked to degenerative changes in the spinal discs and facet joints, which occurs with age.


Different treatment options for a pars defect:

If you have a pars defect without any complications like spondylolisthesis or neurological symptoms, then the best option is to rest and immobilise the area, allowing time for the defect to heal. It is vital that you rest and allow the injury to heal properly before you return to physical activities or sport. Physical therapy can also help to speed up recovery, this may include strengthening and stretching your back.


If there are signs of spondylolisthesis or neurological damage, then the treatment plan will be a little different. Whilst physical therapy and the use of pain medication is still recommended, it may not be as successful. For these cases surgical intervention may be required, this may include a decompression, which will release and free up the nerves that are compressed by the slippage, or a fusion, which will stabilise the spine while it has a chance to heal.


This article is intended to inform and give insight but not treat, diagnose or replace the advice of a doctor. Always seek medical advice with any questions regarding a medical condition.

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