A cervical disc is a cushion-like pad between two bones, or vertebrae, in the neck, and an artificial cervical disc is a manmade replacement used when the original disc becomes damaged. Before artificial cervical discs were created, treatment generally involved removing a damaged disc before fusing together the vertebrae that surrounded it. Using an artificial cervical disc instead allows flexible movement of the neck to be retained and puts less stress on other parts of the spine nearby.
As people age, cervical discs can begin to break down, with the result that the softer inner material may protrude through the fibrous outer layer and press on spinal nerves, causing neck and arm pain. Injury can also cause cervical discs to tear, resulting in similar protrusion. As well as pain, there may be symptoms of weakness and numbness in those areas of the body supplied by any of the squashed nerves. Occasionally the large bundle of nerves running through the center of the vertebrae, known as the spinal cord, may also be compressed causing problems with walking, loss of bladder or bowel control, and muscle stiffness.
In most cases resting and taking anti-inflammatory drugs leads to improvement of symptoms, but if not or if the spinal cord is compressed, artificial cervical disc replacement surgery may be carried out. Through a small incision made in the neck, the damaged disc is completely removed using special surgical instruments. The surfaces of the two vertebrae surrounding the disc are then shaped using a grinding instrument to receive the two parts of the artificial cervical disc. Typically, the artificial cervical disc used will be manufactured from stainless steel with one part, holding a ball, fixed into the upper vertebra and the other part, containing a trough that encloses the ball, fastened into the lower vertebra. Screws are used to fix the steel to the bones.
The surfaces of the metal components used in artificial cervical disc surgery are porous, allowing bone to grow into them and fuse, making the joint more stable. While the vertebrae are held apart during surgery, once the artificial cervical disc is in place the tension is released, and the disc becomes compressed, which helps hold it in position. Recovery from surgery may be quicker than it is following the traditional operation where the neck is fused, there is less pain and fewer complications occur. With an artificial disc, cervical spine movement may be restored to normal levels, but the treatment may not be suitable for everyone, including some people who have arthritis or other diseases that involve numerous discs.