Transforaminal Lumbar Interbody Fusion
Transforaminal lumbar interbody fusion (TLIF) is a fusion technique for the relief of persistent lumbar region, or lower back, pain. TLIF is performed from the side of the back rather than the midline. Transforaminal refers to crossing the foramen, which is the opening within each of the spinal bones that allows nerve roots to pass through. This approach is chosen because it offers the advantages of placing two grafts at once with a very low risk of nerve damage. Interbody fusion refers to the removal of an interverterbal disc, which is replaced with a bone spacer, and the adjacent vertebrae are fused together.
TLIF can be used to treat nerve compression, disc space collapse, spondylothesis and other painful lower back conditions. After obtaining images of the spine with MRI and CT scans, a physician can determine just what type of implant would be best suited to correct the problem.
This surgery is very similar to posterior lumbar interbody fusion (PLIF). They vary in that during TLIF, it is standard to remove the pars interarticularis of the vertebrae. The pars interarticularis is the portion of the bone between the lamina and the pedicle. Removing it in addition to the lamina creates a larger space in which to place the bone graft without putting pressure on the nerve roots. Since the site is only being accessed by one area, complications are generally fewer and recovery is faster and easier than with other fusion procedures.
The TLIF Procedure
The TLIF procedure is performed under general anesthesia with the patient lying face down on an operating table. The treatment site is cleansed with an antiseptic and the surgeon makes a three- to six-inch incision in the side of the back near the affected area. Tools are used to separate and retract the muscles. An imaging device will ensure that the precise vertebrae are targeted. Next, the lamina and pars interarticularis are removed to provide a better view of the nerve roots. The injured disc, bone spurs or any other nearby debris are then taken out. This restores room for the nerves that have been compressed, relieving pain and symptoms in the lower back and legs.
To fill the space that has been created, a bone graft or bone morphogenetic proteins are then attached in the open disc area along with any necessary instrumentation to promote stability in the spine. Often, two spacers containing the graft material will be placed, with one positioned on each side of the interbody space. The surgeon carefully inserts the spacers, avoiding the spinal cord and nerves present nearby. In addition, metal plates, rods and screws are attached as needed to hold the spinal bones in place while fusion is occurring.
Bone morphogenetic protein (BMP) is an FDA-approved treatment used in conjunction with spinal fusion surgery to stimulate bone growth within the treated area and achieve optimal results without the need for a bone graft. However, bone grafts taken from another part of the patient’s own body or obtained from donor bone are also highly successful.
Once complete, imaging is used again to confirm the placement of the spacers and instrumentation. The surgeon can then close up the incision with sutures or surgical staples. The TLIF surgery may vary in length, generally lasting between three and six hours, depending on the extent of the damage in the spine.
Lateral Lumbar Interbody Fusion (XLIF)
Lateral lumbar interbody fusion (XLIF) is a spinal fusion technique performed from the side of the body rather than from the back or through the abdomen. Spinal fusion procedures are performed for the relief of persistent pain in the lower back, the lumbar region of the spine. Interbody fusion refers to surgery in which an interverterbal disc is removed and the adjacent vertebrae are joined. The connection between the two vertebrae is accomplished through the use of a bone graft or through the insertion of bone morphogenetic protein, a manufactured substance also naturally found in the body. XLIF can be used to treat nerve compression, disc degeneration, spondylothesis and other painful lower back conditions.
Benefits and Limitations of XLIF
XLIF is different from other forms of fusion surgery because it uses a lateral, or side, approach to the spinal column. Approaches from the posterior, or back, necessitate the disturbance of muscles, nerves, blood vessels and ligaments in the back. Approaches from the anterior, or front, of the body pass through the abdominal muscles and come near the aorta and other vascular structures and urinary organs.
By approaching from the side of the body, the spine can be reached with minimal tissue damage and minimal risk. In addition, the side approach to the spine provides access to the damaged disc without requiring removal of any vertebral bone. Since the XLIF process is minimally invasive to the muscles and tissues at the site, complications are fewer and recovery is faster than with other fusion procedures.
XLIF, however, can only be performed on vertebrae that can be reached from the side and no more than two levels of the spine can generally be treated with this procedure. Also, XLIF is not performed to treat the lowest vertebrae on the spine. For these reasons, XLIF is not appropriate for all patients.
The XLIF Procedure
Once the incision is made, a probe is inserted to assist the surgeon in detecting compressed nerve roots and avoiding healthy nerve tissue. Dilators are used to separate and gently retract the muscles. An imaging device helps to ensure precision as the surgeon removes the injured disc, bone spurs and any other nearby debris. This restores room for the nerves that have been compressed.
A bone graft or bone morphogenetic protein is then inserted into the space that has been created. BMP has been approved by the FDA to stimulate bone growth in spinal fusion surgery. Once the surgeon has inserted the spacer that contains the graft material, being careful to avoid the spinal cord and adjacent nerves, metal plates, rods and screws are attached as needed. These instruments will hold the bones in place, maintaining spinal stability as the vertebrae grow together.
Once the XLIF procedure is complete, imaging is used again to confirm accurate placement. The surgeon then closes the incisions with sutures. Depending on the extent of spinal damage being repaired, the XLIF procedure takes between 1 and 3 hours.