The bones of the spine are normally stacked like blocks, forming a column. If one of these bones slips forward over the one below it, doctors call the condition spondylolisthesis. This can cause low back pain, deformity, and nerve damage. Surgery for this back condition in adults isn’t always successful.
Fusion surgery to join and hold the problem bone in place is the usual treatment for severe slippage. The bones are joined together with a bone graft. Sometimes a rod is also attached alongside the spine. This helps hold the spine while the bone graft fuses in place.
There are two schools of thought about fusion for severe spondylolisthesis. Some doctors fuse the spine “as is,” just holding the bones in place. This keeps the slippage from getting worse. Others advise trying to move the bones back toward a more normal position. This is called reduction.
Those who prefer reduction surgery say that it keeps the bones from slipping even more after the fusion. It also improves the way the patients look and walk. But there are problems with reduction surgery. Neurological problems are common. Moving the slipped vertebra back can put strain on the spinal nerves. It can also cause men to have trouble ejaculating because the sperm moves up back inside the body. This is called retrograde ejaculation.
A new method of holding the vertebra in place has been tried. Doctors at the Institute for Spinal Disorders in Houston, Texas, used pieces of bone to act as a strut. The dowel-shaped bone is tapped into a hole drilled between the lowest backbone and the sacrum below it. The sacrum is the triangle-shaped bone at the base of the spine, between the pelvis bones. The strut helps the lower backbone resist forward pressure over the sacrum.
Partial reduction with strut grafting can be used in cases of spondylolisthesis of the lowest lumbar vertebra. The strut is protected with a rod alongside the bones. This allows the fusion to heal around the strut and helps prevent further slippage.