Each vertebrae of the human spine is a complete ring-like structure, with central vertebral canal consisting of spinal cord and nerve fibers. For better understanding, the vertebrae can be divided into three portions, the front portion (anterior) is called “vertebral body” and the middle portion consists of pedicles on either side of the spinal cord and the posterior (rear) portion consists of facet joints(superior and inferior), pars interarticularis, and the spinous process. Any break or discontinuity in pars interarticularis is called Spondylolysis.
Spondylolysis (also referred to as “pars fracture”) is usually a fracture caused by repetitive stress rather than a break due to injury, and commonly occurs during childhood or adolescence. The crack may affect only one side, but there are quite a few cases with fractures on either side of the vertebra. When this happens, a vertebra could slide forward or backward onto another one; a condition that is known as spondylolisthesis.
Illustration of the Spinal Column and Location of a Pars Fracture (Spondylolysis)
Spondylolysis is a common condition in physically active children and teenagers. While some of them may experience symptoms, others may not develop symptoms until later in adulthood.
The symptoms include pain and stiffness in the lower back that gets aggravated with activity and gets better with rest. Hyperextension or abnormal stretching of the lower back will usually worsen the condition as it overloads the pars fracture.
At times, nerve symptoms such as “pins and needles” sensation in a leg, with or without numbness or weakness, may be experienced.
The evaluation for this condition will usually involve a review of the patient’s medical history and a physical examination, followed by X-rays to detect pars fractures.
The doctor may advise a bone scan for early detection of a stress fracture of the pars. In this procedure, chemical "tracers" are injected into the blood stream. The tracers converge in areas of increased metabolism or cell activity in bone tissue, indicating a stress fracture of the pars interarticularis, and then show up on special spine X-rays.
To evaluate a pars defect and visualize healing bone, a CT scan may be used, while to assess the surrounding tissue and condition of the disc an MRI may be recommended.
Spondylolysis treatment is initially nonsurgical and includes rest and bracing, which can last up to 3-4 months. The fracture is assessed with a series of X-rays/ bone scan/ CT scan every few months to see if it has healed.
Physical therapy can also be used to help maintain and strengthen the muscles of the abdomen and back with specific directed exercises.
If pain persists after non-surgical treatment, surgery may be required. There are two operations that may be performed:
- Pars repair: This is a minor surgery, wherein the pars fracture is fixed with screws and bone graft, with the principle of bony fusion like any other fracture.
- Interbody fusion: If the procedure is delayed, there can be degeneration of the disc and increased pressure on the nerve roots, wherein pars repair is contra-indicated, then Transforaminal Lumbar Interbody Fusion is performed.