The intervertebral fusion cage is a large, hollow cylinder made of high-grade 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. 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. This approach can be much less damaging to normal tissue and can speed recovery.

The intervertebral fusion cage is designed to spread the two vertebrae apart. This increases the openings in the back of the spine where the nerve roots leave the spine, making more room for the nerves and decreasing irritation. It also tightens surrounding ligaments, decreasing segmental instability and mechanical pain.