Spinal fusion is the surgical technique to stabilize the spinal bones, or vertebrae, and the disc, or shock absorber, between the vertebrae. The goal of lumbar fusion is to create solid bone between two or more vertebrae. A solid fusion between two vertebrae stops the movement between the bones. This reduces pain from motion and nerve root inflammation. Spinal fusion may be recommended for conditions such as spondylolisthesis (slippage of one vertebra over the one below), degenerative disc disease, or for recurrent disc herniations despite multiple surgeries.

Our spine neurosurgeons perform lumbar fusion using several techniques. The method described here is called minimally invasive surgical transforaminal lumbar interbody fusion (MIS-TLIF), an adaptation of a posterior lumbar interbody fusion (PLIF). MIS-TLIF surgery provides unilateral access to the disc space through the intervertebral foramen.

Surgical Hardware called instrumentation, is applied to the spine. A special spacer, called a fusion cage, is inserted into the disc space from one side of the spine. Bone graft material is placed into the interbody space and along the side and back of the vertebra to be fused. Dr. Morrison will usually obtain bone graft from the patient’s pelvis, although bone graft substitutes are sometimes used. These substitutes avoid having to obtain bone graft from the patient. As the bone graft heals it joins (fuses) the vertebra above and below, forming one solid bone. TLIF provides fusion of the front and back of the lumbar spine. The front portion of the spine, called the anterior column, is stabilized by the interbody spacer and bone graft. The back portion, or posterior column, is locked in place with pedicle screws, rods and additional bone graft, alongside the backs of the vertebra.

Lumbar fusion is indicated in patients who have failed conservative treatment and have disabling back and/or leg symptoms. Specific diagnoses include: spondylolisthesis, degenerative disc disease, and recurrent herniated disc–all leading to chronic, mechanical back pain. The MIS-TLIF procedure addresses the disc as a pain generator in causing the chronic mechanical back pain and eliminates the disc as the source of that pain. The goal of a spinal fusion operation is to obtain a solid bony union between two or more vertebra.

Potential advantages of the TLIF procedure are:

• The procedure can allow the surgeon to obtaining a fusion of both the anterior portion of the spine and the posterior portion of the spine through a single posterior approach.
• The chance for a successful fusion is increased due to the larger area for bone graft placement. Bone graft can be placed both in the area behind the vertebrae, to the side of the vertebrae and in the disc space between the vertebrae.
• The disc space and spinal canal is approached from the side. This allows the surgeon to perform the operation with minimal stretching of the nerve roots. The exposure of the spinal canal is done from one side only.
• The special spacer that is placed between the vertebrae helps restore the space between the vertebrae (the disc space). This can help reduce irritation and pressure on the nerve roots from bone spurs and thickened ligaments that can be a source of leg pain

Patients are usually placed face down on a special spine table . This position allows the doctor to operate on the back of the spine. It also lets the abdomen relax, which reduces blood loss during the procedure. General anesthesia is used, meaning patients are asleep during surgery

The surgeon begins by making a vertical incision over the section to be fused. Some doctors perform the TLIF surgery “percutaneously,” meaning only two small openings are made in the skin.

The skin, muscles, and soft tissues are gently spread . Dr. Morrison works through the main incision and separates the tissues over the back The bone that is taken from the spine is prepared for use later in the MIS-TLIF procedure.

Preparations are made to insert pedicle screws. The surgeon watches on a fluoroscope (an X-ray that can be seen on a video screen) to determine the exact spot to place the screws. The screws are inserted through the pedicle bones of the vertebrae to be fused. For example, if two vertebrae are in need of fusion, four screws are used, two on the left and two on the right.

Our expert spine neurosurgery team enlarges the opening around the nerve root, the “foramen. ” An osteotome is used to cut the bone that surrounds this passageway. Enlarging the foramen takes pressure off the nerve root and gives the surgeon more room to do the TLIF surgery through the foramen.

(“Transforaminal” means through the foramen). The nerve root going through the foramen is gently moved aside for the remainder of the TLIF procedure.

The disc between the two vertebrae to be fused is removed. The surgeon inserts a special surgical tool called a rongeur through the foramen and cuts a small “window” into the back of the disc. The disc is removed by working from the back toward the front of the disc space. When the disc and remaining fragments have been cleared away, the surgeon prepares the bony surfaces of the vertebral bodies where the disc was removed.

The surface of the vertebral body within the disc space is called the end plate. By shaving the endplate with a curette, bleeding then occurs. The bleeding is needed to stimulate healing of the bone graft that will be placed into the interbody space.

Dr. Morrison then prepares to insert the spacer into the disc space between the vertebral bodies. The spacer, sometimes called a “fusion cage,” is made either of bone, titanium, or carbon fiber reinforced polymer. Most are hollow so that bone graft material (taken from the pelvis or in the form of a bone substitute) can be packed inside the spacer. Our spine neurosurgeon then measures the size of the disc space to ensure the best fit of the spacer.

Working through the foramen, the Dr. Morrison inserts the bone graft material into the front half of the disc space. Next, a cage is placed into the back half of the disc space and pushed as far as possible to the opposite side. A second spacer is inserted next to the first spacer. This completes the steps for fusing the front of the vertebrae (the anterior column).

Stabilizing the posterior column is completed by adding strips of bone graft along the side and the back of the vertebrae to be fused. Next, Dr. Morrison realigns the surgery frame to give the low back a slight inward curve. Metal rods or plates are attached to the pedicle screws.

Tightening this instrumentation compresses the vertebrae to be fused.

Patients usually need to stay in the hospital for zero to three after MIS-TLIF surgery. An intravenous narcotic pain medicine is used to control pain for the first few days. Fluids are also given through the intravenous line. A catheter will be placed in the bladder. Your blood counts are checked to determine if a blood transfusion is needed

Patients begin a walking program the day after surgery. A physical therapist will usually schedule an appointment to help you learn to get out of bed and walking safely. You might even need a walker for the first few days. Your doctor may have you wear a back brace when you are up and about

When patients go home, they are usually given a prescription for oral narcotic pain medication.

Minimally Invasive Surgical Transformational Lumbar Interbody Fusion is a newer and effective method of fusing the lumbar spine. The goal is to improve back pain by stopping the irritation that causes mechanical and nerve pain. A successful result makes back symptoms better but not perfect. Most studies show that patients have about 60% improvement in their back and leg pain with MIS-TLIF surgery. More than 80% of patients who have TLIF surgery are satisfied with their surgery and recovery.

MIS-TLIF usually results in solid bone fusion with good pain improvement. However, there is no guarantee that the result will be successful.

MIS-TLIF surgery has advantages of increased fusion rate and decreased complications through a posterior approach. Spinal fusion is a salvage reconstructive procedure. No patient after a spinal fusion is 100% normal or 100% pain free.

Complications do occur but are not common, and the majority of patients are satisfied with their pain relief and the results of the surgery. It is critical that patients contemplating spinal fusion surgery are prepared both physically, as well as psychologically. All questions should be answered. Smoking should be stopped. This article has provided an overview only of this MIS-TLIF lumbar spinal fusion. Additional details should be reviewed with our South Florida neurosurgeon clinic so that all questions and concerns are discussed.