The impact of a Spinal fusion
A spinal fusion is a surgical procedure allowing two or more vertebrae to be fused. We have used different names like “Spondylodesis” for orthopedic surgeons or Neurosurgeons to stabilize the spine at any level: Cervical, Thoracic or Lumbar areas. A fusion is performed to restore stability to a segment of the spine.
There are many types of fusions using different kind of material like the patient own bone (autograft), a donor bone (allograft) or some kind of substitute or artificial substances allowing the bone to in-grow. Bone metamorphic proteins (BMP) have also been used in anterior discectomy and fusion of the cervical spine but are expensive and bring more complications like soft tissue swelling or difficulty in swallowing which can impose pressure on the respiratory tract. Hardware like plates and screws or cages can enhance the stabilization and facilitate bone repair.
This procedure is commonly offered after failure of conservative treatment, to relieve pressure on the spinal cord and relieving pain due to the wear of vertebral discs between two or more vertebrae in relation to a degenerative process, an accident or a benign or malignant vertebral tumor etc. This can also be performed on people presenting spinal deformity like Scoliosis or Kyphosis, spinal stenosis or spondylolisthesis
A spinal fusion changes the dynamic of the spine and brings more stress above and below the level fused, creating secondary degeneration in time. Degenerative arthritis is the most common cause of pressure on the spinal cord requiring such a procedure. The presence of osteophytes or bone growth will generate pressure as well as create a spinal stenosis. Often in the same condition, the thickening of the longitudinal spinal ligament will contribute to the spinal stenosis.
Symptomatic patients will develop neck pain and lower extremity discomfort (neurologic claudication). Pressure at the level where the nerve exit in the spinal cord will create also radicular symptoms to the upper or lower extremities. In severe cases, neurologic deficits like numbness, tingling, bowel and bladder dysfunction and even paralysis.
Surgery are more often performed at the cervical and lumbar levels than thoracic. This carry with the procedure, complicating condition bringing bone loss, infection or nerve damage.
An American study has shown that more than 450,000 spinal fusions were performed in 2010’s. Lumbar fusions were the most common followed by Cervical fusions in patients ranging between 45 and 50 years with a 0.25% mortality. The cost for a spinal fusion have increased from 25,000 dollars in 1998 to 81,000 dollars in 2008. Revision surgery can be more expensive.
This procedure is widely performed but still has shown little effectiveness. A decompression and fusion for spinal stenosis has shown no statistical benefit in 5 a years’ post-operative, over a simple decompression. Other who benefited from surgical treatment for radicular symptoms with degenerative arthritis have shown no improvement in pain or function over the one who benefited from intensive rehabilitation only.
The surgical techniques offered were a combination of decompression with bone graft or artificial bone graft packed at the joint space via anterior, or posterior or lateral approaches supplemented with bone plates and screws or rods. Nowadays, minimally invasive decompression and fusion are becoming more popular allowing less damage to the muscles, and less blood loss in a shorter hospital stay assuring less infections.
In the lumbar spine, Postero-lateral fusion with pedicles screws and bone graft extending between the transverse process of each vertebra on each side where the intervertebral disc is replaced by bone graft with a device interposed between the vertebrae (cage in plastic or titanium). The Interbody fusion can be anterior (ALIF) via an anterior approach through the abdomen, Posterior (PLIF) and the disc is approached posteriorly or a Transforaminal lumbar interbody fusion (TLIF) where the disc is approached on a posterolateral position or a Transpsoas interbody fusion (DLIF-XLIF) where the disc is approached through the psoas muscle on the side or an Oblique lateral lumbar interbody fusion (OLLIF) where the disc is approached from an oblique incision in the Psoas muscle.
Spinal Fusion is a high risk surgery with potential serious complications as death especially in older patients with medical problems, poor nutrition and advanced neurological problems. Blood loss and Nerve damage during the surgical procedure is expected, while wound infection, deep vein thrombosis and pulmonary embolism or urinary retention can be expected in the immediate post op. Later, one can expect infection, pseudarthrosis, epidural fibrosis or arachnoiditis.
Everybody has heard the say: “Once back pain, always back pain”. European countries are more conservative than Americans in the treatment of back problems, but the recovery from surgical treatment is variable depending on surgeon preference and the type of procedure chosen. A length of stay of 3 to 4 days is expected nowadays when such surgical procedure is offered. If the surgery interest the cervical spine a shorter hospital stay is expected and can be performed as an outpatient procedure. The same can be expected when minimally invasive surgical treatments are offered.
While recovering from surgery, modifications in activities with a rehabilitation program will assure a successful outcome. Routinely, patients will be out of bed as soon as possible, in the post-operative period with ambulation as tolerated alternate with sitting with occupational upper extremities exercises. Driving can be permitted in 3 months. A return to work can be planned between 6 weeks and 3 months.
Results in spinal fusion can be deceiving and many surgeons have looked for other alternative to conservative treatment. Recent advances in prosthetic replacement especially in the cervical or lumbar spine has gained interest and many institutions have specialized in the procedure. The use of a prosthetic device has replaced in expert’s hands cervical fusion of any type especially in patients with or without cervical radiculopathy.
Many recent studies have evaluated patients with myelopathy with or without radicular symptoms, associated to degenerative cervical spines and have tried to bring an alternative to the use of a cervical arthroplasty prosthesis to replace the standard anterior cervical discectomy and fusion. This appears that more time will be needed to draw more conclusion on the use of the different procedures in the treatment of such patients with degenerative arthritis with or without radiculopathy and myelopathy.
Maxime Coles MD
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