Once the decision is made to proceed with the surgery, the goal is to create a solid fusion. At each level in the spine, there is a disc space in the front and paired facet joints in the back. Working together, these structures define a motion segment and permit multiple degrees of motion. Two vertebral segments need to be fused together to stop the motion at one segment, so that an L4-L5 (lumbar segment 4 and lumbar segment 5) spinal fusion is actually a one-level spinal fusion.

A spine fusion surgery involves using bone graft to cause two vertebral bodies to grow together into one boney segment. Bone graft can be taken from the patient’s hip (autograft bone) during the fusion surgery, or taken from cadaver bone (allograft bone). Synthetic bone graft substitutes are also in development, and one type - bone morphogenic proteins (which helps the body create bone) - is currently being used for certain fusion procedures.

Certain things can negatively impact the chances of obtaining a successful fusion, including smoking (nicotine), obesity, osteoporosis, chronic steroid use, diabetes mellitus or other chronic illnesses, prior back surgery or attempted fusion, multi-level fusion, radiation for cancer treatment, and malnutrition.

Spine fusion surgery options

• Posterolateral gutter fusion—the procedure is done through the back and the harvested bone graft is laid out in the posterolateral portion (just outside) of the spine

• Posterior lumbar interbody fusion (PLIF)—the procedure is done from the back and includes removing the disc between two vertebrae and inserting bone into the space created between the two vertebral bodies

• Anterior lumbar interbody fusion (ALIF)—the procedure is done from the front and includes removing the disc between two vertebrae and inserting bone into the space created between the two vertebral bodies

• Anterior/posterior spinal fusion—the procedure is done from the front and the back and is a combination of the ALIF and posterolateral gutter fusion procedures

• Transforaminal interbody fusion (TLIF)—fuses both the front and back portions of the spine through a single approach through the back of the spine

While anterior fusions (from the front) are less invasive, not all situations are appropriate for this approach.

A lumbar spinal fusion is most effective for those conditions involving only one vertebral segment. Most patients will not notice any limitation in motion after a one-level fusion. Fusing two segments of the spine may be a reasonable option for treatment of pain if needed. Fusion of more than two segments is unlikely to provide pain relief because it removes too much of the normal motion in the back and places too much stress across the remaining joints. Only in rare cases should a three (or more) level fusion for pain alone be considered, although it may be necessary in cases of scoliosis and lumbar deformity.

• Elements of a spine fusion • Surgical techniques for spine fusion surgery • Preoperative preparation for fusion surgery • Postoperative care for spinal fusion surgery

The principal risk of this type of surgery is that a solid fusion will not be obtained (nonunion) and further surgery to re-fuse the spine may be necessary. The patient should also be aware that even if fusion is successful, that does not assure that the pain will go away. As with any surgery, there is a chance of complications such as infection, bleeding, and anesthetic complications. Another potential complication of fusion surgery in the low back includes any type of nerve damage.

After a spine fusion surgery, it takes approximately three months for the fusion to successfully set up and achieve its initial maturity. During these first three months, it is necessary to follow the surgeon’s postoperative care instructions and avoid activities that may place the bone graft at risk. For many patients who undergo a one level fusion further activity restrictions after three months may not be necessary. Permanent restrictions are only needed in a few cases. Actually, since bone is a live tissue, after it has set up it will get stronger with stress (activity).

Fusion surgery success rates are quoted at between 70 and 95%. Surgery for painful conditions that arise from gross instability tends to be more reliable. Also, surgery in those individuals that have only one badly degenerated disc (especially L5-S1) and otherwise have a normal spine tend to fair well. Success rates drop for multilevel degenerative disc disease, or in individuals that still have good maintenance of their disc heights.

It should be kept in mind that the vast majority of spine fusions are elective in nature, and should only be considered in those individuals that have failed conservative treatment, yet still have significant activity restrictions.

Back