The spine is controlled and stabilized by three systems working together to enable and limit movement of the spine. The first system, known as the passive system, includes the vertebrae, facet joints, and ligaments, and stabilizes bending and twisting movements. The active system, composed of muscles and tendons, ensures stability when the movement is neutral and does not include bending or twisting. The last system involved is the neural system, or the nerves that control muscles in the spine. If any of these delicate systems are not functioning correctly, the other systems attempt to compensate to keep the spine stable, an imbalance that can lead to stress and injury.
Abnormal spinal movement can cause pain, specifically when nerves in the impacted area are pinched or irritated. Patients with spinal instability often experience back spasms. These muscle spasms are the compensation of the muscles attempting to prevent the spine from moving too much.
Spinal fusion surgery is performed to stabilize an area of the spine that is moving in an abnormal way. Through the surgical fusion process, spinal vertebra and discs are connected with a bone graft. The bone graft fuses the vertebra above and below the unstable area, forming one bone and eliminating movement. Transforaminal Lumbar Interbody Fusion (TLIF) is one technique utilized by surgeons to reduce pain from motion and nerve root inflammation. TLIF may be recommended for patients suffering from a variety of spinal conditions.
Conditions Treated by TLIF
- Spondylolisthesis: This condition occurs when one vertebra slips forward on the adjacent vertebrae. The condition may be congenital (hereditary), or the result of physical stresses on the spine or spinal degeneration. It may produce both a gradual deformity of the lower spine and also a narrowing of the vertebral canal, and can cause back pain, leg pain and other symptoms.
- Degenerative Disc Disease: Degenerative disc disease is part of the natural process of growing older. As we age, our intervertebral discs lose their flexibility, elasticity, and shock absorbing characteristics. The outer fibers that surround the disc, called the annulus fibrosis, become brittle and are more easily torn. At the same time, the soft gel-like center of the disc, called the nucleus pulposus, starts to dry out and shrink. The combination of damage to the intervertebral discs, the development of bone spurs, and the gradual thickening of the ligaments that support the spine can all contribute to degenerative arthritis of the lumbar spine.
- Recurrent Disc Herniation: Herniation describes an abnormality of the intervertebral disc that is also known as a “slipped,” “ruptured” or “bulging” disc. This process occurs when the inner core (nucleus pulposus) of the intervertebral disc bulges out through the outer layer of ligaments that surround the disc (annulus fibrosis). This tear in the annulus fibrosis causes pain in the back at the point of herniation. If the protruding disc presses on a spinal nerve, the pain may spread to the area of the body that is served by that nerve.
In TLIF, the surgeon begins by making an incision in the back. This gives access to the disc space that is impacted by one of the conditions discussed above. The next step of the surgery involves applying instrumentation, including pedicle screws, into the vertebra. Once there is open access to the affected area, the surgeon removes bone spurs and other overgrown areas to provide more space for the spinal nerves. The disc that is degenerated or herniated is also removed. A spacer, called a fusion cage, is inserted into the disc space, giving the area the same height that was previously occupied by the disc. The spacer provides support to the spine and expedites the bone fusion process.
When the spacer is correctly positioned, bone graft material is placed in the space and along the side and back of the fusing vertebra. The bone graft is generally taken from the patient’s pelvis, but can also be composed of synthetic materials, preventing the need for taking it from the patient. When the bone graft is placed in the spacer area, it begins the process of fusing the vertebra above and below, forming one bone. Additional bone is placed on the sides of the vertebra. After the screws are attached to rods or plates and the graft is secured, the wound is closed.
According to Spine-health, studies indicate that the patient’s pain is improved 60% to 70% after TLIF spinal fusion surgery and approximately 80% of patients undergoing TLIF spinal fusion surgery are satisfied with the surgical result. As with any surgery, however, there are issues about which you will want to speak to your surgeon. Dr. Jonathan Lewin is an experienced spine surgeon specializing in the latest techniques. He is adept at individualizing care for each patient and can speak to you about TLIF or other appropriate procedures for your spine condition.