13 Sep The Anatomy and Process of Spinal Fusion
Spinal fusion is a procedure that is used to treat patients who experience pain due to certain spinal disorders. Simply put, it is a “welding” process that fuses the vertebrae together which allows it to then heal into a single solid bone. It is a procedure that has been performed for decades. There are a few different techniques that can be used to fuse the spine. It is a procedure that can be recommended for conditions such as scoliosis, kyphosis, injured spinal vertebrae, or unstable spine. It is most commonly performed on the cervical (neck) spine or the lumbar (lower back). To understand more about the process and anatomy of spinal fusion, there are some facts that need to be known.
- Basic anatomy –
The spine is made up of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal. In between the vertebrae are intervertebral discs that function as a shock absorber. It also allows the spine to move with minimal friction. Facet joints fit between two vertebrae allowing movement while the foramen between gives space for the nerve roots to travel from the spinal cord to the rest of the body. Certain disorders cause the intervertebral disc to wear down and cause friction between the vertebrae leading to pain.
- Reasoning –
Spinal fusion aims to stop the affected vertebrae from moving. By stopping motion, patients experience relief from symptoms such as pain. It is especially useful in conditions where the intervertebral discs are worn out.
- Incision site –
Depending on the approach the surgeon takes, an incision can be made in different areas of the body.
- Anterior: An anterior approach means that the surgery is done by making an incision in the front of the body. After the incision is made, the organs (such as intestines, kidneys, etcetera) will be moved to the side to allow the surgeon visual access to the spine.
- Posterior: A posterior approach means that the surgeon gains access to the spine through the back. After the incision, the back muscles are moved aside so that the surgeon can access the spine.
- Lateral: A lateral approach means that the spine is accessed through the side of the body. Certain parts of the lumbar spine can be reached through the side.
- The fusion process –
All spinal fusion will require a material to promote the fusion. After the diseased disc is removed, a bone graft can be used where small pieces of bone are inserted into the space between the vertebrae to stimulate bone production and healing. Other material includes demineralized bone matrices (DBMs), bone morphogenetic proteins (BMPs), ceramics, and more. The type of material used in the procedure will depend on the patient’s condition and surgeon.
To ensure that healing and fusion happen in the correct position, screws, metal plates, and metal rods can be used to create a solid “brace” that holds the vertebrae and increases stability. This is known as internal fixation. It also allows the patient to return to their activities of daily living faster. Removal is not necessary unless it causes discomfort.
- Lumbar fusion: a patient’s guide to posterior lumbar fusion with pedicle screws and rods. University of Maryland Medical Center. Accessed 8/5/2017.
- Spinal fusion. American Academy of Orthopaedic Surgeons. Accessed 8/5/2017.