The goals of a lumbar spinal fusion procedure are to strengthen the spine and prevent painful movements and is used to treat back or leg pain caused by degenerative disc disease. The surgeon will stabilize the spine by fusing vertebrae together with bone graft material. Typically, both are achieved by removing one or more damaged intervertebral discs and then "fusing" together the adjacent vertebrae utilizing bone grafts and/or metal devices secured by special screws.
This surgery is commonly performed for isthmic spondylolisthesis, degenerative spondylolisthesis, degenerative scoliosis, multiple recurrent disc herniations, and chronic discogenic low back pain. Conservative measures such as physical therapy, steroid injections, anti-inflammatory medications, and activity and job modifications should be tried at length before the surgery is entertained.
The fusion may take the form of posterolateral fusion, anterior fusion, posterior interbody fusion, or combination of these procedures. Pedicle screws are almost always used to immobilize the fusion area while the fusion is taking place. It takes about 6 months for the fusion to consolidate and smoking severely interferes with this process. Circumferential fusion or 360 fusion in the form of anterior posterior fusion or combined posterolateral and posterior interbody fusion may be performed in smokers to increase the fusion success rate.
Posterolateral lumbar fusions usually take about 4 hours. Combined or circumferential fusions take additional two hours.
Success rate of the surgery vary depending on patient's diagnosis. Usually 80 to 90 % success rate is achieved in isthmic spondylolisthesis, degenerative spondylolisthesis, degenerative scoliosis, and multiple recurrent disc herniations. Success rate is lower in lumbar fusions treating chronic discogenic low back pain syndrome.
Complications of the surgery include about 1 to 2% chance of return back to operating room for pedicle screw malpositioning, a small risk of nerve injury, about 3 % chance of wound infection, excessive bleeding, and other medical complications such as postoperative pneumonia or heart attack. Very rarely epidural hematoma causing paralysis can occur if patients had been taking blood thinners immediately prior to surgery. Therefore patients should stop taking all types of blood thinners such as coumadin and anti-inflammatory medications including Vioxx and Celebrex at least one week prior to surgery.
Hardware complications such as broken rods or screws can occur. Fusion may not heal requiring additional surgery later on. At times levels adjacent to the fusion area may wear out gradually causing so-called transitional syndrome requiring another operation, usually extension of fusion later on. This is more common more levels are fused. With one level fusions the incidence is 5% or less. Pedicle screws are FDA approved for treatment of degenerative and isthmic spondyloisthesis and fractures of lumbar spine but not for other indications and patients should be aware of these. The screws have been in use for more than 20 years. The screws greatly enhance fusion success rate and they are essential and indispensable in achieving successful fusion in this surgeon's opinion. To further enhance fusion success interbody devices such as cages or structural allograft bone may be used in the disc space.
Patient's own bone is used for the fusion and this is usually taken from the posterior iliac crest. This is usually obtained using the same incision as the fusion surgery. In some patients bone graft donor site pain can be severe but in most of the cases this is not a real problem. Patient's own bone works best but if it is lacking for various reasons bone substitute which is both osteoconductive and osteoinductive may be used. For postop recovery information please refer to a separate heading in this web site.