Low Back Pain and Leg pain :: Lumbar Disc Herniation :: Lumbar spinal stenosis :: Spondylolisthesis :: Spondylolysis (Pars Defect)

Spondylolysis is a defect in a relatively weak area of a vertebra called the “pars interarticularis”, or commonly referred to as “the pars”. The terms “Spondylolysis” and “Pars Defect” refer to the same thing. Although it is often referred to as a “break” or “fracture”, in most cases it is not caused by an injury. Approximately 8% of the population is believed to have spondylolysis in the lumbar spine (most common level is L5, then L4), so the presence of this finding on X-rays should not be alarming for patients (and parents). Most people with spondylolysis have no pain and in fact are not even aware they have this X-ray finding.

Spondylolysis is frequently seen in adolescent athletes who may complain of low back pain. Sports that require repetitive hyperextension of the low back, such as football (linemen), gymnastics, wrestling, and cheerleading may predispose to this injury but all athletes regardless of their sport can present with this finding. In athletes, spondylolysis can be thought of as a “stress fracture” due to repetitive hyperextension of the low back.

It is extremely rare for spondylolysis to occur as a result of a single traumatic injury, such as a car accident or a bad fall. Again, this condition is most commonly due to repetitive overload, or an overuse injury.


Most people with spondylolysis have no symptoms. Many people with low back pain have an X-ray of their back done, and are told they have spondylolysis. However, this X-ray finding may or may not be the source of their pain. It is more likely to be a source of pain in competitive athletes who are likely “overstressing” their body. In these patients, the pain worsens with vigorous physical activity, and improves somewhat with rest. Patients occasionally have some discomfort or numbness in the leg(s), but the main complaint is typically low back pain that is worsened with back extension.


Plain X-Rays are often obtained which show the pars defect. In some cases (especially in adolescent athletes), the X-rays fail to show the defect and either a CT scan or a Bone Scan may be needed for diagnosis. A study that combines these 2 tests (CT scan and Bone Scan) is called a SPECT scan and is the best test for definitively diagnosing this condition. Although an MRI is also a good test for diagnosing this problem, the SPECT scan is more accurate than an MRI for this condition.


Most patients with spondylolysis (without spondylolisthesis) can be treated conservatively with a period of rest, physical therapy and sometimes bracing. The natural history is favorable, and most patients can return to their previous level of activity after appropriate treatment.

In adolescent athletes, the first step is to stop the activity that has aggravated the pain. This means a period of rest (at least 6 weeks) during which time the patient does not participate in sports. Again, spondylolysis in the young athlete is an overuse injury, and the importance of rest cannot be overemphasized. Another important component of treatment is a focused physical therapy program to strengthen the core musculature, avoiding lumbar extension exercises (extension puts more stress on the pars region). Stretching the hamstrings is also important. Anti-inflammatory medications may be taken as needed. Bracing is used on occasion and the main reason to use a brace is to remind the patient to avoid certain back movements. In essence, the brace is a means of promoting activity restriction. Most patients have complete relief of their pain in 6-8 weeks with the above treatment protocol. Injections may be an option if the pain persists despite the above.

Surgery for spondylolysis (without spondylolisthesis) is rarely required and is reserved for patients who have exhausted all nonsurgical options and still have significant back pain. In most patients surgery has very good results. The surgery is called a “direct pars repair” and is accomplished by inserting screws and hooks to stabilize the pars defect. This surgery is recommended only if the pars defect is determined to be the source of the pain.