Spinal fusion is designed to reduce pain in patients with damaged bones in the spine. Surgeons may perform the procedure through the abdomen, called the anterior approach, or through the back or posterior approach. A posterior lumbar inter-body fusion, or PLIF, involves removing the disk between bones of the lower back; inserting a spacer made of bone, plastic or metal; and using screws, plates or rods to provide additional stability, according to the American Academy of Orthopaedic Surgeons. Over time, the bones fuse together into a single unit. The posterior approach is the more familiar route, but is not without risks.
Nerve Damage
When the surgeon uses the posterior approach for lumbar inter-body fusion, she must move the spinal cord and nerves aside in order to reach the disk, the fluid-filled pad that acts as a shock absorber between pairs of vertebrae. This necessary manipulation of the nerve roots can cause damage to the nerves and bleeding that result in scar tissue that presses on the nerves, according to the Society of Gastrointestinal and Endoscopic Surgeons. These injuries can cause long-term pain in some patients. In rare cases, nerves to the legs, bowel or bladder may be damaged, causing loss of normal function, according to John E. Sherman, M.D., in a report published in the Sept. 8, 2006, issue of "Spine-Health."
Altered Anatomy
Using the posterior approach may actually destabilize the spine, according to the SAGES website. When the surgeon uses the posterior approach, he must alter the normal anatomy by removing a piece of bone in order to reach the surgical field. The posterior approach also makes it more difficult for the surgeon to maintain or restore the normal space between the vertebrae after the disk is removed. A narrowing of the space may cause pressure on the nerve roots, causing pain.
Pseudoarthrosis
Pseudoarthrosis, a potential complication for any type of spinal fusion, is the term for the failure of the bones to fuse together, according to the University of Maryland Medical Center. The spine remains unstable, causing pain and possible damage to the hardware--plates, screws or rods--that was used. The surgeon may recommend a second surgery to replace the hardware, add more grafting material or implant an electrical stimulator to facilitate healing.
General Risks
As in any type of surgery, the patient may experience excessive bleeding, blood clots, infection or breathing problems, according to the UMMC. All procedures involving the spine could result in failed back syndrome in which the bones heal, but the patient's pain is not relieved. Transitional syndrome may also occur, a phenomenon that causes pain above or below the fused portion due to increased stress on those sections of the spine.
