Introduction:

The intervertebral fusion cage is a large, hollow cylinder made of some type of metal, usually titanium. It is designed as a "cage" so that bone graft can be placed inside the hollow cylinder to allow a spinal fusion to occur between two vertebrae. The holes that are throughout the cage allow bone to form around and through the cage connecting the two vertebrae with solid bone.

Many of the newer types of intervertebral fusion cages are also designed to allow performing the spinal fusion either using an open incision or a laparoscopic procedure. An open incision is the traditional way of performing surgery, where larger incisions are made to allow the surgeon to see where he is operating and perform the procedure. A laparoscopic procedure is performed using much smaller incisions and using a special TV camera inserted into the abdomen to allow the surgeon to see where he is operating and perform the procedure. The laparoscopic approach can be much less damaging to normal tissue and can speed recovery. On the other hand, the laparoscopic approach is sometimes very difficult to perform and may not be possible in all cases.

The intervertebral fusion cage is designed to do several things. First, the cage is used to spread the two vertebrae apart, which allows several things to occur. The openings in the back of the spine where the nerve roots leave the spine become larger - making more room for the nerves. This decreases the pinching and irritation on the nerves. The strong ligaments that surround the disc tighten as the cage forces the vertebrae back apart. This decreases the segmental instability between the two vertebrae and decreases the mechanical pain in the spine. Second, the intervertebral fusion cage sits between the two vertebrae to replace the disc and hold the two vertebrae in the correct position until a fusion occurs between the vertebrae.