Can you tell me which way is better to go with a spine fusion -- bone graft from my hip or the newer bone substitutes? I know there are plusses and minuses with each one. But is one ever recommended over the other?

Spine fusion is usually done as a last resort when conservative (nonoperative) care fails to reduce painful back and/or leg symptoms from degenerative disc disease or chronic disc herniations. Usually, the surgeon removes the disc and either puts a special device in that space (called an interbody spacer) or fills the hole with bone graft material.

Even with the interbody spacer, bone graft material is inserted in and around the area to help foster bone growth and subsequent fusion. Whenever bone graft is used, there are several different choices. There are two kinds of human bone graft: allograft (bone from a donor bank) or autograft (bone taken from the patient's pelvis). A third choice is the use of rhBMP-2 bone substitute. rhBMP-2 stands for recombinant human bone morphogenetic protein type 2, so you can see why they shortened it to rhBMP-2. This protein stimulates the body's natural production of bone.

As you said, there are pros and cons with each one. Bone graft from a bone bank doesn't always take. Sometimes the body recognizes it as a foreign substance and sets up an immune response against it. But it does eliminate the need for an extra incision and harvesting of bone that is required with an autograft. Donor site pain, infection, and poor wound healing are often the biggest problems following a lumbar fusion with autograft.

Bone substitutes are not without their own issues. Studies have reported up to a 35 per cent complication rate using a bone substitute in lumbar fusions. Complications include screws coming loose or placed in the wrong position, interbody cage movement called migration, and infection. Sometimes pockets of blood form called hematomas or too much bone forms, a condition called heterotopic ossification. There can also be enough disturbance in the area of the spinal nerves that results in persistent nerve pain.

Leg pain from nerve irritation is called radiculitis. It is a common complication and one that is more likely when rhBMP-2 is used without a special agent called . Duraseal is a water tight sealant that keeps the bone substitute from leaking into the spinal canal or around the nerve roots where it could act as an irritant. Without the Duraseal, there is also a risk of bone formation in the spinal canal, which could put pressure on the spinal cord causing pain and dysfunction.

When it's all said and done, both ways of accomplishing fusion are safe and effective but not without potential complications. Your surgeon may have some preferences in the choice based on experience and perhaps some individual factors in your case. Be sure and find out what his or her recommendations might be.