DEFINITION AND DESCRIPTION
Spinal fusion is a major surgical procedure that fuses two or more adjacent vertebrae. This procedure provides stability by eliminating motion, and also can relieve the pressure off the spinal nerve or the spinal cord. A neurosurgeon or an orthopedic spine surgeon will insert a bone graft in the space between two vertebrae and stabilize the segments by means of a metallic construct (plate screws, anchors, rods and cages). This construction will hold the vertebrae together so the bones can heel into a solid unit. The bone graft is either acquired from the patient’s pelvis (autograft), from a bone bank, or it is a synthetic bone. It takes 2-3 months after surgery to have a solid bony fusion.
This type of surgery takes several hours to complete, requires a few days of hospitalization and a few months of rehabilitation after discharge from the hospital. The fused segment is immobile, which places additional stress and strain on the vertebrae above and below, and may accelerate the rate of degeneration at those areas. Fusion will take away some spinal flexibility, but in most cases it involves 1-2 segments and does not limit motion very much.
Spinal fusion is indicated in a few spine disorders, including severely painful degenerative disk disease, unstable spondylolisthesis, severe or progressive scoliosis, vertebral fracture or pars fracture, spinal infection or spinal tumors.
TYPES OF FUSION
The surgical approach to spinal interbody fusion can be from the front (anterior spinal fusion –ALIF or ACDF), from the back (posterior spinal fusion -PLIF), from one side (lateral XLIF or transforaminal TLIF), or a combination of front and back (anterior and posterior) techniques. The decision is made based on the clinical scenario, mechanism of injury, imaging, risk factors, surgeon’s preference and skills, as well as degree of invasiveness necessary to have a successful outcome.
As with any surgery, spinal fusion carries the potential risk of complications. Complications can be related to anesthesia, surgery or the hardware/bone graft. Complications can develop at the time of surgery or in the days, weeks or months following the surgery. A list of potential complications includes: bleeding, infection, blood clot, injury to blood vessels, nerves or spinal cord injury, pain at the site from which the bone graft is taken, poor wound healing (diabetics), non-fusion (smokers or diabetics), chronic pain (failed back syndrome), sexual dysfunction (lumbar fusion), difficulty with swallowing (cervical fusion) and adjacent level degeneration. Hardware migration and hardware fracture also may develop soon after surgery requiring a revision or removal.