Do I Need Spinal Fusion?
Arthrodesis, more commonly known as “spinal fusion,” is a procedure that is very common in modern spine surgery. The goal of spinal fusion is to create a single, fixed spinal segment from one or more mobile spinal segments. There are many ways to accomplish this surgically, including removing the intervertebral disc and replacing it with locally harvested or cadaver bone and a plastic or metal spacer (commonly referred to as a “cage”), or by laying bone along the back of the spine. A common adjunct to this is internal fixation of the fused segment with screws, to prevent motion of that segment while the bone heals across the space. Patients that require spinal fusion typically have one or more dysfunctional motion segments. Dysfunctional motion segments typically cause deep, agonizing back pain or neck pain which is worsened with activity (loading) and relieved with rest. This is known as mechanical back pain. Common causes of dysfunctional motion segments include spinal deformity such as degenerative spondylolisthesis where one vertebral body is slipped forward in relation to its neighbor, or severe degenerative spondylosis where there is near total degeneration of the intervertebral disc and inflammation in the vertebral end-plates. Pain from a dysfunctional motion segment differs from (but can be commonly seen with) radiculopathy (commonly refered to as “sciatica” in the lumbar spine). Radiculopathy is characterized as sharp, shooting pain, almost of an electrical quality, down a given extremity. Radiculopathy can be seen in many spinal pathologies, but one of the most common settings is in disc herniations. Disc material can protrude from its normal anatomic location, and if it encounters a neighboring nerve root, it can produce radiculopathy. In many scenarios a simple decompression surgery can take care of radiculopathy without the need for fusion. There are many times when fusion is necessary, for instance if the surgeon needs to surgically destabilize a spinal segment in order to most effectievly remove the herniated disc (as in the case of an anterior cervical discectomy and fusion) or if the radiculopathy is seen in conjunction with an underlying deformity that does not respond well to decompression alone (such as nerve compression in the setting of a spondylolisthesis). When considering a fusion vs a decompression, it is important to differentiate mechanical back pain from radiculopathy, as radiculopathy often (but not always) requires decompression alone, without spinal fusion.