Spine surgery is a complex decision-making process. There are decompression surgeries and there are surgeries that involve both decompression and fusion and it is important to understand the difference between the two.
If a patient has mechanical back pain or instability, the two bones would get fused together so that abnormal motion is stopped, thus providing relief of that pain. Fusion procedure includes mechanical or axial pain with activity (this refers to any type of back pain caused by placing abnormal stress and strain on muscles of the vertebral column).
If a patient is determined to be suffering from radicular pain or leg pain caused by compression of a nerve root, a decompression surgery may be appropriate. A decompression surgery involves removal of bone and ligament to free the nerve from that compression, thus alleviating the leg pain.
Another minimally invasive technique following a decompression of the nerve root is to place an interspinous spacer between the spinous process or laminas, thereby creating an indirect decompression of the existing nerve and taking the pressure off the nerve root.
Many people have heard negative stories surrounding fusion surgery. I believe that if surgery is done for the right indication, patients tend to do very well.
Typically, a fusion procedure includes mechanical or axial pain with activity that may be approaching the spine from an anterior or a lateral approach that allows much less muscle destruction, as well as a fast recovery. If one comes in posteriorly, often it can also be performed as a minimally-invasive procedure with minimal muscle disruption. A fusion surgery will also involve stabilization; whether it be rods and screws posteriorly or plates anteriorly which acts as an internal brace so that the bones can heal together.