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Spinal fusion, also called spondylodesis or spondylosyndesis..
It is a surgical technique that joins two or more vertebrae.
Four trials have showed that spinal fusion is no better than physical therapy at relieving back pain , still, it is used more often in the US as a technique than before the studies were published.
It can be performed at any level in the spine i.e., cervical, thoracic, or lumbar and prevents movement between the fused vertebrae.
There are multiple types of spinal fusion and each technique involves using bone grafting, or artificial bone substitutes, to help the bones heal together.
Hardware such as screws, plates, or cages are often used to hold the bones in place while the graft fuses the two vertebrae together.
The procedure is most commonly perform to relieve pressure and pain on the spinal cord that results when a spinal disc degenerates.
The most common cause of pressure on the spinal cord/nerves is degenerative disc disease.
Other conditions that are treated by spinal fusion include spinal stenosis, spondylolisthesis, spondylosis, spinal fractures, scoliosis, and kyphosis.
Spinal stenosis results from bony growths or thickened ligaments that cause narrowing of the spinal canal over time.
Complications may include infection, blood loss, and nerve damage.
Fusion alters the normal motion of the spine and causes more stress on the vertebrae above and below the fused segments, with degeneration at these adjacent spine segments.
Spinal fusion can be used to treat any level of the spine: lumbar, cervical and thoracic.
In general, it is performed to decompress and stabilize the spine, with its greatest benefit appears to be in spondylolisthesis, and evidence is less good for spinal stenosis.
Pressure on the nerves as they exit the spinal cord, ref2242ed to as radiculopathy, causes pain in the area where the nerves originated: leg for lumbar pathology, arm for cervical pathology.
In severe cases, nerve pressure can cause neurologic deficits, like numbness, tingling, bowel/bladder dysfunction, and paralysis.
Lumbar and cervical spinal fusions are more common than thoracic fusions as degeneration occurs more frequently at these levels due to increased motion and stress.
The thoracic spine is more immobile, so most fusions are performed due to trauma or deformities like scoliosis and kyphosis.
Spinal fusion is for:
Degenerative disc disease
Spinal disc herniation
Discogenic pain
Spinal tumor
Vertebral fracture
Scoliosis
Kyphosis
Spondylolisthesis
Spondylosis
Posterior rami syndrome
Other degenerative spinal conditions or condition that causes instability of the spine.
Use of bone morphogenetic protein is not be routinely used in anterior cervical spine fusion, such as with anterior cervical discectomy and fusion, as it may cause soft tissue swelling, which in turn can cause life-threatening complications due to difficulty swallowing and pressure on the respiratory tract.
Lumbar fusions are the most common type of fusion performed with about 210,000 per year. 24,000 thoracic fusions and 157,000 cervical fusions are performed each year.
Average age for spinal fusion was 54.2 years, 53.3 years for primary cervical fusions, 42.7 years for primary thoracic fusions, and 56.3 years for primary lumbar fusions
Average length of hospital stay was 3.7 days with 2.7 days for primary cervical fusion, 8.5 days for primary thoracic fusion, and 3.9 days for primary lumbar fusion.
In-hospital mortality was 0.25%.
In a randomized controlled trial of sufferers of spinal stenosis, after 2 and 5 years there was no significant clinical benefits of lumbar fusion in combination with decompression surgery, in comparison to decompression surgery alone.
A systematic review on surgery for lower back pain found that for nonradicular low back pain with degenerative disk disease, there was no benefit in health outcomes of performing fusion surgery in comparison to intensive rehabilitation including cognitive-behavioral treatment.
Researchers in Washington State viewed lumbar fusion surgery to have questionable medical benefit, increased costs, and increased risks, in comparison to intensive pain programs for chronic low back pain with degenerative disk disease.
Following decompression surgery bone graft or artificial bone substitute is packed between the vertebrae to promote healing.
Fusions may be done either on the anterior, posterior,or both sides of the spine.
Most fusions are supplemented with hardware to include: screws, plates, and rods.
These hardwares because have higher union rates than non-instrumented .
Minimally invasive surgery uses advanced image guidance systems to insert rods/screws into the spine through smaller incisions.
Minimally invasive surgery allows for less muscle damage, blood loss, infections, pain, and length of stay in the hospital.
Types of fusion techniques performed at each level of the spine:
Anterior approach to cervical spine.
Anterior cervical discectomy and fusion
Anterior cervical corpectomy and fusion
Posterior cervical decompression and fusion
Thoracic spine anterior decompression and fusion.
Posterior instrumentation and fusion.
Lumbar spine posterolateral fusion is a bone graft between the transverse processes in the back of the spine: vertebrae are then fixed in place with screws or wire through the pedicles of each vertebra, attaching to a metal rod on each side of the vertebrae.
Interbody lumbar fusion is a graft where the entire intervertebral disc between vertebrae is removed and a bone graft is placed in the space between the vertebra.
A plastic or titanium device may be placed between the vertebra to maintain spine alignment and disc height.
Types of interbody fusion are:
Anterior lumbar interbody fusion (ALIF) – the disc is accessed from an anterior abdominal incision
Posterior lumbar interbody fusion (PLIF) – the disc is accessed from a posterior incision
Transforaminal lumbar interbody fusion (TLIF) – the disc is accessed from a posterior incision on one side of the spine
Transpsoas interbody fusion (DLIF or XLIF) – the disc is accessed from an incision through the psoas muscle on one side of the spine.
Oblique lateral lumbar interbody fusion (OLLIF) – the disc is accessed from an incision through the psoas muscle obliquely.
Spinal fusion has a higher risk of complications in older people with elevated body mass index (BMI), other medical problems, poor nutrition and numbness, weakness, bowel/bladder issues before surgery.
Complications depend on the type/extent of spinal fusion surgery.
Fusion surgery complications:
Patient positioning on operating table
Blood loss
Damage to nerves and surrounding structures during procedure
Insertion of spinal hardware
Harvesting of bone graft
Wound infections
Deep vein thrombosis
Pulmonary embolism
Urinary retention
Malnutrition
Neurologic deficit
Deformity such AUB loss of height, alignment, and failure of fusion
Pseudarthrosis – nonunion between fused bone segments.
Adjacent segment disease – degeneration of vertebrae above/below the fused segments due to increased stress and motion.
Epidural fibrosis – scarring of the tissue that surrounds the spinal cord
Arachnoiditis – inflammation of the thin membrane surrounding the spinal cord, usually caused by infection or contrast dye.
Recovery following spinal fusion is extremely variable, depending on individual surgeon’s preference and the type of procedure performed.
Walking – most people are out of bed and walking the day after surgery.
Sitting – can begin at 1–6 weeks following surgery.
Lifting – it is generally recommended to avoid lifting until 12 weeks.
Driving – usually can begin at 3–6 weeks.
Return to sedentary work – usually between 3–6 weeks.
Return to manual work – between 7–12 weeks
Rehabilitation after spinal fusion is not mandatory.