There are a series of steps performed to complete an XLIF spinal fusion:
- First, the patient will be positioned lying on his or her side. Then the surgeon will use X-rays to locate the disc that will be removed.
- Once the disc is located, the surgeon will mark the skin with a marker directly above the disc.
- Then the surgeon will make a small incision (cut) in the flank (low back region of the trunk) and use his or her finger to push away the peritoneum (sac covering the abdominal organs) from the abdominal wall.
- The surgeon will make a second incision directly on the side of the patient.
- The surgeon will then insert a tube-like instrument known as a dilator into this incision.
- The surgeon will use X-rays to make sure that this dilator is in a good position above the disc.
- The surgeon will then insert a probe (blunt tool) through a muscle known as the psoas muscle. The psoas muscle is a large muscle that runs from the lower spine, wrapping around the pelvic area and attaches at the hip.
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Because nerves exiting the spinal column are close to the psoas muscle and can even run right over the surface of it, it is critical that the surgeon be provided with real-time information about the position of the nerves relative to his instruments. Neuromonitoring, the testing of the nerves during surgery to make sure that they are not harmed or irritated during the process, is a critical part of this procedure. This type of nerve monitoring is known as electromyography or EMG. The neuromonitoring system used with the XLIF procedure, (NeuroVision, NuVasive, Inc.) is designed to accomplish this goal. The NeuroVision probe is designed to detect the position of the nerves to help avoid disturbing them during surgery. Although NeuroVision helps identify neural compromise before it is clinically relevant, it is not a perfect process and there is still a risk of neural damage during the procedure.
- Once the muscles are split apart, a retractor tool (MaXcess, NuVasive, Inc.) is put into place to give the surgeon direct access to the spine.
- Once this direct access to the spine is achieved, the surgeon is able to perform a standard discectomy (removing the intervertebral disc) with tools designed to cut and remove the disc.
- After the disc material is removed, the surgeon is able to insert the implant through the same incision from the side. This spacer (cage) will help hold the vertebrae in the proper position to make sure that the disc height (space between adjacent vertebral bodies) is correct and to make sure the spine is properly aligned. This spacer (CoRoent XL, NuVasive, Inc.) together with the bone graft, is designed to set up an optimal environment to allow the spine to fuse at that particular segment.
- The surgeon will take an X-ray to make sure that the spacer is in the right position.
Sometimes, depending on the diagnosis of the patient, additional support is needed to hold the vertebrae in place. In this case, the surgeon may also decide to put in an additional implant, such as screws, plates or rods for added support.
A single-level XLIF procedure takes approximately one hour to perform.