Lower Back Issues

Lumbar Spondylolysis

Causes
Spondylolysis is thought to be caused by repeated strains that damage the lower spine over time. The repeated strains can eventually lead to an overuse injury in the pars interarticularis. The most common location for this to occur is in the lowest vertebra of the spine, which doctors call L5. This vertebra connects the spine to the pelvis. However, a problem with the pars can occur in any lumbar vertebra. It rarely happens in more than one vertebra at a time.

The vertebra initially responds to the abnormal strain by adding new bone cells around the injured area. But if the injuries happen faster than the body can keep up with needed repairs, a crack may form in the weakened bone. This is called a stress fracture. This type of fracture occurs in the pars, the area of bony ring between the pedicle and lamina.

The crack may affect only one side of the bony ring. However, it is equally common for the defect to occur on both sides. When this happens, the vertebra is no longer held firmly in place by the facet joints on the back of the ring. As a result, the vertebra is free to slip forward over the one below. This slippage, which is closely related to spondylolysis, is called spondylolisthesis.

Spondylolysis commonly occurs in young gymnasts who regularly practice backbends as part of their routines. Football linemen and dancers are also prone to spondylolysis. Symptoms sometimes appear when an athlete quickly ramps up his or her training intensity, applies incorrect technique, or uses poor equipment.

Symptoms
People with spondylolysis may feel pain and stiffness in the center of the low back. Bending fully backward increases pain. Symptoms typically get worse with activity and go away with rest. Doctors refer to this type of back pain as mechanical pain because it most likely comes from excess movement between the vertebrae.

Individuals may eventually experience pain that radiates down one or both legs. This pain may come from pressure and irritation on the nerves that exit the spinal canal near the fracture. When nerve pressure in the low back causes leg pain, doctors refer it as neurogenic pain.

The cause of this nerve pressure is a result of the body’s attempt to heal the stress fracture. Over time, the healing process may cause a bump of extra cartilage to grow at the site where the bones are trying to heal the overuse injury. If too much cartilage builds up, this bump may intrude into the opening where the nerves exit the spine. The bump may squeeze the nerve. This can produce pain and weakness in the leg. Reflexes become slowed. The person may also notice a pins and needles sensation in the skin where the spinal nerve travels.