Lumbar Fusion
Lumbar spinal fusion is a surgical technique in which one or more of the vertebrae of the spine are fused together so that motion no longer occurs at those levels. Bone material is placed around the spine and over several months, the bones will heal subsequently joining or welding the vertebra together. Lumbar spinal fusion is typically done in conjunction with a lumbar laminectomy.
INDICATIONS FOR LUMBAR FUSION
There are several reasons for patients to undergo a lumbar fusion. These include spinal fractures, instability, correction of deformity, and in cases of spinal tumors. Instability of the spine is typically referred to as spondylolisthesis. This is the most common indication for a lumbar spinal fusion. There are many types of lumbar spinal fusion. These all involve placement of bone graft between the vertebrae to fuse the vertebrae together. Ultimately, the goal of a spinal fusion is to obtain a solid union between the bones. One of several factors that can impair development of a solid union between the bones after spinal fusion surgery is smoking. Therefore, patients are highly encouraged to stop smoking before and after any sort of spinal fusion.
LUMBAR SPINAL FUSION
Lumbar spinal fusion can be performed with or without use of instrumentation. Instrumentation refers to the use of screws to stabilize the spine. The determination of whether a patient requires instrumentation or not is complex and is based on the patient’s age, bone quality, activity level, and other medical conditions. This will be discussed with the patient thoroughly prior to surgery. In the case of a lumbar spinal fusion without instrumentation, bone graft is placed over the outer aspects of the spine called the transverse processes. This is typically done after the nerves have been decompressed. The bone that is typically used for this fusion purpose is bone that has already been removed during the laminectomy part of the procedure. This bone is occasionally mixed with synthetic bone to help with the fusion.
LUMBAR SPINAL FUSION WITH INSTRUMENTATION
In cases when it is determined that the patient would benefit from instrumentation, screws, called pedicle screws, are placed within the bone of the levels that need to be fused in the spine. These screws are placed based on anatomic landmarks and are typically checked intraoperatively with x-ray and an intraoperative CT scan. Once the screws are placed, they are then connected with two rods and, similar to an uninstrumented fusion, the bone graft is placed over the outer aspect of the spine over what is called the transverse processes. Again, depending on the amount of bone graft that is available, the bone may be mixed with some synthetic bone to help increase the volume of the bone graft. The screws and rods are placed in order to stabilize the spine until the bone graft and fusion heals.
LUMBAR INTERBODY FUSION
Lumbar interbody fusion refers to removal of the disc between the vertebra and placement of bone graft within the disc along with an implant typically made of plastic called PEEK. The purpose of an interbody fusion is to increase the potential healing rate and fusion by also fusing the disc space. Again, the bone graft used in this case is the patient’s own bone, which is removed from the laminectomy and possibly mixed with synthetic bone. Again, the decision whether to perform an interbody fusion is complex and determined by your surgeon prior surgery.
POSTOPERATIVE COURSE
The most common complaint after lumbar fusion is back pain. This is typically managed with pain medications and muscle relaxers after surgery. Most patients are able to be up and ambulating the day after surgery and this is highly encouraged. Depending on the type of fusion that was performed, patients are typically in the hospital for anywhere from two to five days after surgery. Depending on the patient’s job and degree of physical activity that is required, patients can return to work anywhere from two to six weeks after surgery.
RISKS AND/OR COMPLICATIONS
As with any surgical treatment, there are inherent risks. These include risk of anesthesia, bleeding, nerve damage, blood clots, bowel and bladder dysfunction, spinal fluid leak. As with any spinal fusion surgery, there is a risk of the bone not healing, which may necessitate further surgery and/or possible loosening of the instrumentation if instrumentation is used during the fusion.