What is Pars Defect
Pars defect is a painful condition that affects the lower spine. It is actually a stress fracture that occurs in the region of the vertebrae called pars interarticularis (or just pars). The pars interarticularis acts as a bony bridge between joints, and helps to keep the vertebra in place. Fractures in this bony section can be difficult to mend and the broken ends do not achieve union completely, leading to a permanent separation.
This condition causes the upper front portion of the vertebra to move against the lower back portion in the absence of the stabilizing effect of the pars. This condition is also known as Lumbar Spondylosis.
Cause of Pars Defect
Pars defect is believed to be caused by repetitive strain to the lower back or lumbar section of the spine, and typically affects the fifth and fourth lumbar vertebrae. It is usually a result of severe and repeated hyperextension, backward bending, or rotation of the back. It is found to occur on one side of the vertebrae, usually opposite to the side involved in the stressful activity.
Who Usually Suffer from Pars Defect
Pars defect is seen commonly in young athletes whose spines are subjected to this type of frequent repetitive strain. It is commonly seen in athletes that participate in sports such as gymnastics, high jump, pole vaulting, dance, cricket, tennis, weight lifting, football and baseball pitching, which all require stressful lumbar extension and rotation.
While it is not a progressive condition, it can frequently lead to a more serious problem of spondylolisthesis. When the pars stress fractures occur, the front part of the vertebra is no longer held in place to the segment below. This often leads to a forward slippage of the vertebra which is called spondylolisthesis.
Does Genetics Contribute to Pars Defect
There may also be a genetic factor leading to this condition (congenital pars defect). Persons born with thin vertebral bones will be more likely to develop this condition. Periods of rapid growth as seen in adolescents may cause these stress fractures and increase chances of the vertebrae slipping. While common in young adolescent athletes, it can sometimes be observed in adults as well.
Other factors leading to pars stress fractures include poor posture, lack of core stability, muscle tightness, poor exercise or sporting technique, or inappropriate playing surfaces.
Symptoms of Pars Defect
In many people, the symptoms are not very obvious, and this condition is not always painful until there are several stress fractures.
In advanced cases, there is lower back pain which may radiate down to buttocks and thighs. The pain can range from discomfort to dull ache to severe disabling pain. Some patients may feel muscle spasms and tightening of muscles, especially in the hamstring region. If the vertebrae slips considerably, it can also compress the nerves leading to ‘pins and needles’ or tingling sensations.
Diagnosis for Pars defect
X-rays of the lower back (lumbar region). PA, LAT, and Oblique x-ray projections are usually used to evaluate this condition. SPECT bone scan and CT (computed tomography) are other techniques used to confirm this diagnosis. Recent advances in MRI also allow doctors to identify stress injuries to the pars interarticularis before the fractures actually occur. This can be very helpful in preventing or controlling this condition, especially in growing children.
Pars Defect Treatment.
Initial treatment for pars stress fractures is to take a break from the activities causing the pain. Anti-inflammatory medications may be prescribed to help reduce back pain. In some cases, back braces and physical therapy may be recommended. Stretching, flexibility and gentle weight lifting exercises can strengthen the back and abdominal muscles, and provide some relief.
If the vertebrae slippage progressively worsens or if back pain does not respond to other treatments, then surgery may be indicated. Spinal fusion surgery is typically performed between the lumbar vertebra and the sacrum. However, in most cases, rest and restriction from stressful activities is sufficient to manage the symptoms of pars defect.