Spinal fusion is a surgical technique used to join two or more vertebrae in the spine and to minimize the pain caused by movement of these vertebrae. Fusion of vertebrae in the lumbar portion of the spine is called as lumbar fusion and the surgery can be done as an open or minimally invasive procedure.
In spinal fusion, a piece of bone harvested from other parts of the body or collected from a bone bank, is transplanted between the adjacent vertebrae. As the healing occurs, the bone fuses with the spine. This stimulates growth of solid mass of bone which helps in stabilizing the spine. In some cases, metal implants such as rods, hooks, wires, plates or screws are used to hold the vertebra firm until new bone grows between them.
A minimally invasive lumbar fusion technique is used to treat fractured vertebra, lumbar instability, spine deformities – scoliosis or kyphosis, cervical disc hernias, tumors, back pain and failed back syndrome. Spondylolisthesis, a painful condition of the spine caused by disc displacement or slipped disc, can be treated with minimally invasive lumbar fusion technique.
Several techniques are practiced for minimally invasive surgery and they include
Anterior lumbar interbody fusion, ALIF – accessing the spine from the front
Posterior lumbar interbody fusion, PLIF – approaching the spine from the back
Transforaminal lumbar interbody fusion, TLIF – approaching from the side
In anterior approach, four small incisions of length approximately 1/2 inch are made on the abdomen, the muscles and blood vessels are retracted and the vertebrae will be fused.
In posterior approach, several 1–2-inch incisions are made on the back, a series of increasingly larger dilators are used to spread the muscles apart and to provide access to the spine. The rods and screws are placed through the dilator tubes. In some cases, an operating microscope may be used to provide a better view.
In TLIF procedure, a small incision of 2 inches will be made on the patient’s side. The muscles are moved apart and larger dilators are progressively placed down to the lumbar spine. Using specially designed instruments, through the dilator tube, the intervertebral disc is incised and removed. A bone graft or metal or plastic spacer is then placed between the vertebrae. This bone graft then usually heals, forming a solid bone. This technique is used in combination with a posterior approach for placement of rods and screws to strengthen the fusion.
Minimally invasive technique of fusion carries many advantages and they include:
- Minimal damage to the adjacent tissues
- Reduced post-operative pain
- Reduced hospital stay
- Faster recovery
- Diminished blood loss
