The human spinal column is marvel of anatomical engineering composed of a series of vertebral bones and cartilaginous intervertebral discs. This structure supports the musculoskeletal system and protects a vital component of the central nervous system, the spinal cord. Like all mechanical structures, time and use cause wear and tear on the spinal column. Discs erode and bone spurs form, causing pain and limiting mobility. When more conventional methods fail to provide relief, spinal fusion surgery is sometimes prescribed. Options exist regarding the placement of the bone graft and the type of bone graft used for this procedure.
Posterolateral Fusion
Spinal fusion surgery involves the removal of the disc between two adjacent vertebrae and the application of a bone graft to provoke the vertebrae to fuse into one solid bone segment. In posterolateral fusion, the bone graft is placed between the transverse processes of the two adjacent vertebrae, according to Dr. Ali Araghi, an orthopedic surgeon with the Texas Back Institute. These bony structures protrude from the sides of the rear portions of the vertebrae.
Rods and screws may be used in spinal surgeries to stabilize the area during the healing process, and to maintain the proper level of joint space between the vertebral bodies as the graft begins to fuse.
Interbody Fusion
Interbody fusion differs from posterolateral fusion in the placement of the bone graft.
Transforaminal lumbar interbody fusion is a method of interbody fusion surgery used in the lower spine that approaches the spine through the posterior, using an angled position to avoid affecting the spinal nerves. The University of Cincinnati's NetWellness service explains that a bone graft inserted within the disc space and along the back of the vertebrae encourages the fusion to heal with the help of screws and rods.
Autograft Bone Graft
Spinal fusions can also differ in the type of bone graft that is used. A patient who chooses to donate his or her own graft material is undergoing an autograft. The bone graft in these cases is most often harvested from the iliac crest of the patient, an area located in the pelvic bone. This form bone graft is considered the gold standard, according to Araghi, though it can have negative aftereffects, such as postoperative pain and donor site morbidity.
Allograft Bone Graft
An allograft bone graft is composed of tissue harvested from a cadaver. Various types of sterilization and storage techniques are used in allograft bone handling. Some allografts use fresh tissue. Others may be frozen or freeze-dried.
