Sciatica can also be caused by Isthmic spondylolisthesis, yet is much less common.Spondylolisthesis occurs when one vertebrae slips forward and places pressure on the adjacent vertebrae. This condition will produce both a gradual deterioration of the vertebrae in the lower spine and can also cause a narrowing of the spinal canal.
If abnormal motion allows this vertebrae to move back and forth nerves in the spinal canal may be affected causing pain, numbness, tingling or weakness in the legs. Many individuals who have this condition may not have symptoms while others may experience long term back pain and or sciatica.
Spondylolisthesis is most common in the lower spine. The most common cause is degenerative disease (like arthritis) and the slip usually occurs between the fourth and fifth lumbar vertebrae where there is the most curvature in the spine. Muscle imbalances play a major role in two ways:
Other causes of spondylolisthesis include stress fractures (which are often caused by repetitive hyper-extension of the back, commonly seen in gymnasts), and traumatic fractures. Spondylolisthesis may also occasionally be associated with bone diseases. As with the other three conditions, muscle imbalances have a lot to do with spondylolisthesis.