Degenerative spondylolisthesis is a degenerative slippage of one vertebra over the other. It is more common at L4-5 and in aging women (up to 20-25%). The condition is related to degeneration of the disc as well as the facet joints. Degenerative hypertrophy of the facet joints may lead to stenosis. Often there is additional stenosis due to redundant ligamentum flavum and disc bulging. Symptoms are typically low back and buttock pain. Pain, however, is not correlated to the degree of slippage, but rather to the degree of dynamic instability and the degree of stenosis most commonly affecting the L5 nerve root. Most patients do not have neurological deficits.
Nonoperative treatment includes physical therapy, NSAID, part time bracing, and spinal steroid injections. Approximately 10-15% of patients fail nonoperative treatment and go onto surgery. Those that have surgery typically have leg symptoms worse than back pain consistent with more severe stenosis. Decompression only surgery can give good shortterm results. However, there is a long-term risk of progressive spondylolisthesis and recurrence of symptoms. Multiple studies have shown that a fusion combined with decompression gives improved long-term results. A fusion may be challenging in these patients because the condition often occurs in elderly females who have osteoporosis. A workup for osteoporosis in these patients is not routine, as simple DEXA scanning will often read the bone density of the hypertrophic facets rather than the vertebral bodies. Therefore, patients over 60 years of age with back pain need to be evaluated with lateral
spine DEXA scan which avoids the artifact seen on AP only DEXA. Loosening of instrumentation in osteopenic bone may lead to instability, a lack of fusion taking place and progressive pain. Other spinal fusion techniques include interbody techniques in addition to the posterolateral
techniques. The type of fusion and instrumentation depend upon the degree of pain from the unstable disc versus pain from the stenosis. A new technique includes the use of “posterior dynamic stabilization” in addition to the decompression. Whether these new techniques indeed offer the stability that is required to prevent progression of spondylolisthesis recurrence of symptoms is not yet know. These systems also require adequate bone stock to be successful, and once again, all of these patients need evaluation to exclude osteopenia/osteoporosis.
In conclusion, degenerative spondylolisthesis is related to degeneration of the disc and the facet joints. There is a period of instability which leads to the slippage and facet osteophytes which causes stenosis. A few patients require surgery, which entails adequate decompression and usually instrumented fusion.
MD News May 2008