Transforaminal Lumbar Interbody Fusion (TLIF)
Spinal fusion is a technique used to stabilize the spinal bones, or vertebrae. The goal of a lumbar fusion is to create a solid bridge of bone between two or more vertebrae. Solid fusion occurs when two bones mend or weld together, much like a broken bone healing in a cast. Spinal fusion may be recommended for conditions such as spondylolisthesis (forward slippage of one vertebra on top of another), degenerative disc disease, recurrent disc herniation, or failed previous surgery.
A transforaminal lumbar interbody fusion (TLIF) involves placement of posterior instrumentation (screws and rods) into the spine. In addition, a fusion cage is inserted into the disc space from one side of the spine. Bone graft material is placed into the interbody space as well as on the back of the vertebra to allow for fusion [Figure 1].TLIF provides improved results for fusion because fusion is achieve in the front and back parts of the lumbar spine. The interbody fusion occurs in the anterior portion of the spine. Benefits of fusion in the anterior interbody space include an increased area for bone to heal, as well as increased forces that are distributed through this area when the patient stands and walks [Figure 2].
Figure 1: X-rays of the lumbar spine before and after Transforaminal Lumbar Interbody Fusion (TLIF). Titanium screws and rods support the bones and maintain proper alignment in the back of the spine, while a titanium cage has been placed in the disc space between the bones for support in the front portion of the spine. Fusion occurs in both the front and back of the spine.
Figure 2: Diagram showing TLIF. Pedicle screws achieve a solid fixation onto the spine and are connected together by a rod. Bone graft bridges the bones in this area to achieve a spine fusion.
The spine is composed of individual bones called vertebrae. Vertebrae are stacked one on top of another and are separated by the intervertebral discs, which act as cusions or shock absorbers. A circle of bone extends from the vertebral body back around the sac of nerves and spinal cord. This circular protective tube of bone, called the spinal canal, protects the spinal cord and spinal nerves. In the lumbar spine the spinal nerves exit the spinal canal between the vertebrae at each level. Two nerves exit each level, one on the left and one on the right. These nerves exit through openings called foramina [Figure 3]. A transforaminal lumbar interbody fusion is performed through a posterior incision on the back of the lumbar spine. The procedure can be performed through a traditional open incision or a minimally invasive procedure depending on the patient and the condition to be treated.
ADVANTAGES OF TRANSFORAMINAL LUMBAR INTERBODY FUSION VERSUS
STANDARD POSTEROLATERAL FUSION:
Transforaminal lumbar interbody fusion (TLIF) allows the surgeon to obtain a solid fusion on both the anterior and posterior portions of the spine, all through a single surgical approach. The chance of a successful fusion is increased with the TLIF procedure because a larger surface area is available for bone graft to heal into a fusion. TLIF also allows for better restoration of space between the vertebral bones and the space around the exiting nerves in the neural foramen. For patients with spinal curvature or instability, the implant that is placed between the vertebral bodies at the time of surgery helps restore the space and correction of spinal deformity [Figure 4].
Figure 4: X-rays before and after TLIF show correction of scoliosis and restoration of normal alignment.
A lumbar fusion may be indicated for patients with low back pain or pinched nerves. The specific decision to perform a TLIF depends on a number of factors which will be discussed with you by your doctor.
Transforaminal lumbar interbody fusion is performed with the patient under general anesthesia, meaning the patient goes to sleep during the surgery. During the surgery the patient lies face down on a special surgical bed. An incision is made in the back and placement of instrumentation and decompression of spinal stenosis is performed through this incision. Pedicle screws are inserted into the bone to allow for fixation and stability after fusion. The surgeon then enlarges the opening around the nerves as needed depending on the location and severity of the patient's spinal stenosis. The surgeon then works underneath the exiting nerve through the neural foramen, hence the term “transforaminal” [Figure 5].
The disc between the two vertebrae to be fused is then removed. Surgical tools are used to cut a window in the back of the disc and then remove the disc from a posterior approach. Once the disc space has been cleared out, the surgeon prepares the bony surfaces for a fusion [Figure 6]. The surgeon then inserts bone graft and a spacer into the disc space between the two vertebral bodies. The spacer or fusion cage may be made of either bone, titanium, or reinforced plastic. Bone graft inside the disc space will then go on to fuse, healing the two bones together in this area [Figure 7]. Finally, rods are placed between the screws in order to maximize stability and hold the level stable while fusion occurs. Additional bone graft material is also placed along the back of the spine, providing an additional area for spine fusion to occur.
There are multiple options for bone graft material for spinal fusion. The spinal specialists at the Virginia Spine Institute do not usually harvest hip bone or iliac crest bone graft for most spinal fusion procedures. Taking hip bone graft increases postoperative pain and prolongs healing. Surgeons at the Virginia Spine Institute may use a combination of your own bone from the area of the spine being operated on, as well as bone morphogenetic protein (BMP), a genetically engineered substance that stimulates bone healing. For some patients, additional donated and prepared allograft bone is also utilized.
POST SURGERY HOSPITAL CARE:
Patients usually remain in the hospital two to four days after TLIF surgery. Postoperative pain control will be achieved with the use of IV pain medication, epidural pain medication, and oral pain medications. Patients are discharged home on oral pain medication. A catheter is typically placed in the bladder and is removed in the first one to two days after surgery. Patients begin a physical therapy walking program the day after surgery, and a physical therapist works with the patient to learn how to get out of bed and walk safely. Patients need to be comfortable with walking, climbing stairs, and getting in and out of bed before going home. The final goal is to make sure the gastrointestinal and urinary systems are working appropriately. Patients must be able to eat a solid meal and urinate without difficulty prior to leaving the hospital.
Transforaminal lumbar interbody fusion is an approved and effective method for fusing the lumbar spine. The goal of surgery is to decrease pain, correct spinal deformity, and improve stability. Complications occur but are not common. The majority of patients are satisfied with their pain relief and the results of their surgery. All patients should review their specific condition and surgical plan with their surgeon prior to the surgical procedure. It is important that all patients having spine fusion surgery are physically and psychologically prepared for their surgical procedure. All patients should stop smoking prior to their surgical procedure. Please review additional details with your surgeon prior to the procedure.