Lumbar (Low Back) Surgical Implants
Lumbar implants are devices surgeons use to decompress and stabilize the spine (low back). Implants used in lumbar fusion surgery can be divided into 2 groups:
1. Those placed within the interbody space (the "disc space")
2. Those placed onto the spine to provide stabilization
Decompression involves surgically removing tissues pushing or pinching a nerve. Spinal stabilization involves fusing 2 or more vertebrae together. Devices (such as cages, screws, rods) combined with bone graft stop all movement between vertebral bodies.
Interbody Implants (Cages)
The purpose of lumbar interbody implants is to:
1. Maintain disc height between vertebrae to help prevent nerve compression
2. Restore and preserve the lumbar spine's natural alignment
3. Promote spinal fusion
4. Stand alone to provide structural stability
5. Carrier (holder) for fusion material (such as bone graft)
Cages come in different sizes and shapes. Some are cylinders, others box-shaped. They are made from various materials such as metal, bone, carbon fiber, plastic. Cages packed with bone chips or a graft substitute to help the fusion heal. One or 2 cages may be fit into empty disc (interbody) space. Some surgical procedures use only cages to promote fusion and stabilize the spine.
Role of Bone Graft
Whatever implants the surgeon chooses, the final stability of the spine eventually results from fusion - and fusion is enhanced by bone graft. Autograft is the patient's bone and allograft is donor bone. A genetically engineered protein, recombinant human bone morphogenetic protein (rhBMP-2), stimulates the body to produce natural bone rapidly.