Lumbar Total Disc Replacement is the next generation in the surgical care of lumbar degenerative disc disease. A lumbar total disc replacement (TDR) is a motion preserving technology now being used by spine surgeons in place of fusion. TDR aims to replace the degenerative disc, which is the pain generator, with a mobile implant, thus allowing continued motion and preventing adjacent segment degeneration, which is presumed to be the cause of long term failure of fusions. Many patients have found great success with their total disc replacement, which has allowed them to get back to the activities they enjoy.
What is an Intervertebral Disc?
The spine supports and stabilizes your body and allows motion. The spine also provides protection for the spinal cord and nerve roots. Your spine is made up of bones called vertebrae that are stacked on top of each other to form a column. Each vertebra has a hole in the center through which the spinal cord passes. The spinal cord contains nerves that carry signals from your brain to the rest of the body. The vertebrae are separated by soft, cushioning intervertebral discs, which maintain an appropriate space to support motion and allow nerves to pass through the spine to many different parts of the body.
The intervertebral discs of the spine have several important functions, including shock absorption, motion coupling, as well as providing proper spacing between the vertebra.
Shock Absorber – The discs allow the spine to compress and then rebound when the spine is loaded when doing such activities as jumping and running.
Motion Unit – The elasticity of the disc allows motion coupling so the spinal segments are able to flex, rotate and bend all at the same time.
Spacer – The height of the disc maintains the separation distance between the adjacent bony vertebral bodies. This allows biomechanics of motion to occur. The discs also allow the intervertebral facet joints to maintain their height, which allows the segment nerve roots room to exit each spinal level without being compressed.
Degenerative Disc Disease
One of the most common causes of lower back pain is degenerative disc disease. Degenerative disc disease is a natural part of aging but can also be exacerbated by a trauma to the disc. The inherent problem with degenerative disc disease is a result of the disc’s blood supply, or rather, its lack thereof. The spinal discs have minimal blood supply, which brings healing nutrients and oxygen to damaged structures in our body. Thus, the spinal disc lacks any significant reparative powers once it has been damaged and therefore can continue to degenerate over time. If a disc is injured or degenerating, it may become painful because of instability that can lead to an inflammatory reaction, resulting in pain. Also the height of the disc in collapsing the nerve roots, or the spinal cord, can be compressed, causing pain. Common symptoms experienced are numbness, tingling, difficulty sitting, and leg pain.
Many times patients are able to manage their ongoing pain, as well as more painful flare episodes, with non-surgical, conservative treatment. Most surgeons typically ask their patients to undergo at least six months of conservative treatment, which consists of:
Pain Management – Over the counter, prescription medication, and/or epidural steroid injections may be prescribed to get the patient to gain control of their pain.
Active Physical Therapy – Once the patient’s pain is under control, physical therapy is prescribed to improve the resting tone in the deep muscles that run alongside the spine. Strengthening of the back muscles will help offload stresses on the disc and frequently will dramatically reduce pain as well as improve function. A typical physical therapy regiment will incorporate stretching, strengthening and aerobic conditioning.
Behavioral and Lifestyle Changes – Patients with lower back pain should refrain from doing activities that are known to hurt their back. Often, ergonomic office chairs or mattresses are recommended. It is highly recommended that smokers stop smoking because it has been found that smoking further deprives the disc of nutrients needed to maintain height and hydration. Weight loss is also recommended for overweight patients.
Total Disc Replacement
A TDR may be the right option if conservative treatment does not work and severe pain continues to make it difficult to function in everyday activities. The implants used in a TDR are made to be structurally similar to a healthy disc and share similar functions. The implant is composed of top and bottom metal endplates and a plastic inlay that forms a ball and socket joint. The implant disc allows for motion by allowing the top endplate to move over the plastic ball attached to the bottom endplate.
During the total disc replacement surgery, the patient will be under general anesthesia. The surgeon will make a small incision in your abdomen to get to your unhealthy disc. The unhealthy disc is removed and the height at that level of your spine is restored to relieve pressure on the nerves. The implant is then inserted into the disc space. Finally, the surgeon will close the incision.
As with any major surgery, the patient should expect discomfort, as well as a period of rehabilitation. On average, the patient can expect to stay in the hospital for a day or two. The surgeon will help put together a plan to steadily bring the patient back to normal activity while the healing process occurs. Patients are encouraged to begin moving soon after surgery. Most patients return to normal daily activities two weeks after surgery. Recovery time after TDR surgery is generally much faster than what is experienced after spinal fusion surgery. FBN
John Hall, M.D., is an orthopaedic spine surgeon with Flagstaff Bone and Joint.