The Role of the Artificial Disc
The search in medicine is on for body
part replacements. Many devices and parts have been developed to repair
or replace large weight bearing joints and some small extremity joints.
In fact, replacement of painful arthritic joints has become more and
more common. Surgical replacement of hip and knee joints has become
a very successful procedure. It has become one of the most reliable
and functionally restorative operative procedures in the field of orthopedics.
Most spine surgeons have become more conservative in their approaches
attempting to minimize compromise of tissues in the involved spinal
region while also trying to restore or preserve movement of the spinal
Spine specialists appreciate the role of the intervertebral disc of the spine as part of the mechanical system as well as its role as a spacer between the bones of the spine. The physical relationship between tissues of the spine influences the pattern of nerve signals which arise from the tissues during movement. Currently, many spinal surgical approaches involve fusion of adjacent vertebrae resulting in a loss of movement of the spinal segment. This alters the mechanics of that whole region of the spine with the greatest stress placed on neighboring spinal segments. Intervertebral disc replacement can be performed in some situations to help maintain motion at the level of the operation.
The concept of replacing a compromised intervertebral disc with artificial discs is not a new one. Disc replacement surgery has been performed in Europe for more than 10 years. Some spinal implant manufacturers have redirected some of their research funding to investigate the value of the artificial disc. The application of an artificial disc is also referred to as a disc replacement, disc prosthesis or spinal disc arthroplasty. It is essentially a man made device which is surgically placed in the spine between tow adjacent vertebrae to maintain or restore the functions of a normal disc. The primary physical functions are to serve as a spacer, function as a shock absorber, carry a load and to allow for movement. The majority of disc replacements will be in the low back (lumbar spine). Cervical disc replacement can also be performed.
There are different types of artificial
disc designs. The most common is total disc replacement which requires
surgical removal of the original disc. A replacement device is implemented
between the flat surfaces of adjacent vertebrae. Artificial discs are
made of a variety of different materials. Further research will help
identify which materials will work the best from a short term and a
long term perspective. The current artificial discs are usually made
of metal or plastic-like (biopolymer) materials. Some of them are made
of a combination of these materials. These materials have been used
as part of other body implants for many years with good success. The
indications for a total disc replacement versus a nucleus implant will
be different. The type of artificial disc used will depend on many factors
including the condition which is being treated and the integrity and
health of the neighboring spinal segments.
There are risks associated with all surgeries including disc replacement. The complications associated with disc replacement are similar to those of other spine surgeries. The risks include but are not limited to infection, implant rejections, nerve damage, injury to nerves, injury to blood vessels, the development of painful and restrictive scar tissue, intraoperative stroke, drug mediated complications such as anaphylaxes. Long term risk include breakage of the device, dislodgement of the device, abnormal wear of material within the device, failure of adjacent bone, post-operative chronic pain, and the immune rejection of the device. As with any spine surgery there is a risk for the development of new signs or symptoms. Anyone who is a candidate for this procedure must discuss the risk and benefits associated with the procedure in detail. It is also wise to obtain a second and in some case a third opinion before making a final decision. Prior to considering a disc replacement it is important to discuss the matter with two or more spine surgeons. Most people are not good candidate and other forms of intervention should be discussed