Artificial disc replacement surgery may be performed on the lower back or the neck. Artificial discs are structurally similar to the damaged discs that are replaced and share similar functions, including acting as shock absorbers in the back or neck.
The development of the lateral approach for fusion allows today the possibility to offer TDR by this approach when the disc to be replaced is above L5-S1. The risks of the anterior approach are eliminated and the neurophysiological monitoring of the nerves decreases the risk of traction injuries of the lumbar plexus in its transpsoas trajectory.
The XL procedure is what is termed as “minimally invasive” procedure. This means that instead of a traditional, larger single incision, the procedure is performed through one or more small incisions and an instrument known as a retractor is used to spread the tissues so that the surgeon can see the spine. This is made possible by the use of a dilator and retractor system, MaXcess®, developed by NuVasive®, Inc, in San Diego, CA. This system allows the surgeon to reach the spine via lateral access (from the side of the body).
Previous lumbar Total Disc Replacement (TDR) devices require an anterior approach for implantation. This approach has inherent limitations, including risks to abdominal structures and the need for resection of the anterior longitudinal ligament (ALL). Placement of a TDR device from a true lateral (extreme lateral [XL]) approach is thought to offer a less invasive option to access the disc space (reduced risk of interrupting blood circulation in the left leg, significantly reduced risk of arterial thromboembolism, reduced risk of plaque embolism with arteriosclerosis), preserving the stabilizing ligaments and avoiding scarring of anterior vasculature.
When L5-S1 has to be included in the surgical treatment an anterior TDR procedure is performed. Some patients benefit from hybrid procedures; for example, a fusion performed anteriorly ALIF or transforaminal lumbar interbody fusion [TLIF] with cages and pedicles screws at L5-S1 and XL-ADR at the other lumbar levels or Posterior Dynamic Stabilization with Dynesys at L5-S1 and TDR at L4-5 or/and L3-4 could be performed.
Total Disc Replacement.
Extreme Lateral Artificial Disc Replacement Cervical Disc Replacement (ADR)
An artificial disc surgery may be engaged instead of an anterior cervical discectomy and fusion. The theoretical advantages of the artificial cervical disc over a fusion include:
1. Maintaining normal neck motion
2. Reducing degeneration of adjacent segments of the cervical spine
3. Eliminating the need for a bone graft
4. Early postoperative neck motion
5. Faster return to normal activity
ADR treats symptomatic degenerative disc disease more effectively while maintaining spinal motion following anterior discectomy.
The artificial disc is designed to take the place of the real intervertebral disc and be placed between two vertebral bodies, where the disc has been surgically removed, in order to decompress the spinal cord or nerve root in the neck. Ideally the artificial disc acts like a normal disc, providing motion while acting as a shock absorber in the spine (unlike a fusion, which eliminates both motion and shock absorption in the fused segment of the spine). The indications for a cervical disc replacement are generally the same as for a cervical discectomy and fusion. A person must have a symptomatic cervical disc, which may be causing arm pain, arm weakness or numbness with some degree of neck pain. These symptoms may due to a herniated disc and/or osteophytes compressing adjacent nerves or the spinal cord. This condition typically occurs at cervical spine levels C4-5, C5-6, or C6-7.
The standard surgical procedure for a disc replacement is an anterior (from the front) approach to the cervical spine. This surgical approach is the same as that presently used for a discectomy and fusion operations and performed microsurgically with delicate instrumentation. The affected disc is completely removed including any impinging disc fragments or osteophytes (bone spurs).