Lower back pain is the second most common neurological condition after headaches in the United States, according to the National Institute of Neurological Disorders and Stroke (NINDS). Lower back pain may be caused by muscle spasms or injuries, or it could be due to nerve damage or bone lesions. It can result in several chronic conditions, including degenerative disc disease, in which the spongy material between the vertebrae (discs) loses its fluid, and spondylolysis, which is inflammation of the spinal joints that may require surgery to alleviate the pain. Lumbar fusion is a surgical procedure where two or more vertebrae are joined together to limit movement and pain while strengthening the spine.
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An inter-body fusion technique removes the disc from between the vertebrae that will be fused together. The discs are then replaced with a bone spacer made of either metal or plastic. There are three main types of inter-body fusion techniques.
The posterior lumbar interbody fusion (PLIF) technique is performed through an incision in the back (hence, the posterior position) and is usually done when either a single fusion of two vertebrae or a double fusion, which involves three vertebrae, is required. During a PLIF, the nerves are moved aside allowing access for the surgeon to perform a bone graft, or joining, on both the right and left sides of the inter-body space.
A transforaminal lumbar interbody fusion (TLIF) is also performed through an incision in the back. However, during this procedure, the nerves are not moved aside and the bone graft is performed in the middle section of the inter-body space.
An anterior lumbar interbody fusion (ALIF) technique enters the body through an incision made in the abdomen. This type of inter-body fusion is often performed when several discs are involved that need to be fused together. Although the anterior positioning requires the intestines and major blood vessels, including the aorta and vena cava, to be moved aside, the spinal nerves do not need to be moved. This decreases the risk of neurological damage according to the University of Southern California's Center for Spinal Surgery.
A posterolateral lumbar fusion is similar to the PLIF in that the incision is made in the back. However, the two techniques differ because in the posterolateral fusion, the disc space is not removed. Instead, the vertebrae are fused together at the transverse process, which is a protrusion that extends out from each side of the vertebrae.
Facet Joint Fusion
A less commonly performed lumbar fusion surgery is the facet joint fusion. This is where two vertebrae are connected together. Each vertebra has two (one on each side) superior processes located on top of the vertebra and two inferior processes located on the bottom. The facet joint is where the superior processes of one vertebra interconnect with the inferior processes of the vertebra above it. These facet joints make the entire spine one long, stable unit. When the joints are fused together, flexibility of motion may be inhibited, but pain can be reduced.