Spinal fusion, also called spondylodesis or spondylosyndesis, is a surgery performed by orthopaedic surgeons or neurosurgeons that joins two or more

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

. This procedure can be performed at any level in the spine (cervical, thoracic, lumbar, or sacral) and prevents any movement between the fused vertebrae. There are many types of spinal fusion and each technique involves using

bone grafting Bone grafting is a type of transplantation used to replace missing bone tissue or stimulate the healing of fractures. This surgical procedure is useful for repairing bone fractures that are extremely complex, pose a significant health risk to the ...

—either from the patient ( autograft), donor (

allograft Allotransplant (''allo-'' meaning "other" in Ancient Greek, Greek) is the Organ transplant, transplantation of cell (biology), cells, Biological tissue, tissues, or Organ (anatomy), organs to a recipient from a genetically non-identical donor of ...

), or artificial bone substitutes—to help the bones heal together. Additional hardware (screws, plates, or cages) is often used to hold the bones in place while the graft fuses the two vertebrae together. The placement of hardware can be guided by

fluoroscopy Fluoroscopy (), informally referred to as "fluoro", is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a surgeon to see t ...

, navigation systems, or

robotics Robotics is the interdisciplinary study and practice of the design, construction, operation, and use of robots. Within mechanical engineering, robotics is the design and construction of the physical structures of robots, while in computer s ...

. Spinal fusion is most commonly performed to relieve the pain and pressure from mechanical pain of the vertebrae or on the spinal cord that results when a disc (cartilage between two vertebrae) wears out (

degenerative disc disease Degenerative disc disease (DDD) is a medical condition typically brought on by the aging process in which there are anatomic changes and possibly a loss of function of one or more intervertebral discs of the vertebral column, spine. DDD can take ...

). It is also used as a backup procedure for total disc replacement surgery ( intervertebral disc arthroplasty), in case patient anatomy prevents replacement of the disc. Other common pathological conditions that are treated by spinal fusion include spinal stenosis,

spondylolisthesis Spondylolisthesis is when one spinal vertebra slips out of place compared to another. While some medical dictionaries define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (o ...

spondylosis Spondylosis is the degeneration of the vertebral column from any cause. In the more narrow sense, it refers to spinal osteoarthritis, the age-related degeneration of the spinal column, which is the most common cause of spondylosis. The degener ...

spinal fracture A spinal fracture, also called a vertebral fracture or a broken back, is a bone fracture, fracture affecting the vertebrae of the spinal column. Most types of spinal fracture confer a significant risk of spinal cord injury. After the immediate tr ...

scoliosis Scoliosis (: scolioses) is a condition in which a person's Vertebral column, spine has an irregular curve in the coronal plane. The curve is usually S- or C-shaped over three dimensions. In some, the degree of curve is stable, while in others ...

, and

kyphosis Kyphosis () is an abnormally excessive convex curvature of the Spinal column, spine as it occurs in the Thoracic spine, thoracic and sacrum, sacral regions. Abnormal inward concave ''lordotic'' curving of the Cervical spine, cervical and Lumba ...

. Like any surgery, complications may include infection, blood loss, and nerve damage. Fusion also changes the normal motion of the spine and results in more stress on the vertebrae above and below the fused segments. As a result, long-term complications include degeneration at these adjacent spine segments.

Medical uses

Spinal fusion can be used to treat a variety of conditions affecting any level of the spine—

lumbar In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm (anatomy), diaphragm and the sacrum. Naming and location The lumbar region is sometimes referred to as the lowe ...

, cervical and

thoracic The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main ...

. In general, spinal fusion is performed to decompress and stabilize the spine. The greatest benefit appears to be in

, while evidence is weaker for spinal stenosis. The most common cause of pressure on the spinal cord/nerves is degenerative disc disease. Other common causes include disc herniation, spinal stenosis, trauma, and spinal tumors. Spinal stenosis results from bony growths (

osteophytes Osteophytes are exostoses (bony projections) that form along joint margins. They are distinct from enthesophytes, which are bony projections that form at the attachment of a tendon or ligament. Osteophytes are not always distinguished from exost ...

) or thickened ligaments that cause narrowing of the spinal canal over time. This causes leg pain with increased activity, a condition called neurogenic claudication. Pressure on the nerves as they exit the spinal cord (

radiculopathy Radiculopathy (; ), also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). Radiculopathy can result in pain (radicular pain), weakness, altered se ...

) causes pain in the area where the nerves originated (leg for lumbar pathology, arm for cervical pathology). In severe cases, this pressure can cause neurologic deficits, like numbness, tingling, bowel/bladder dysfunction, and paralysis. Lumbar and cervical spinal fusions are more commonly performed than thoracic fusions. Degeneration happens 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

, and lordosis. Conditions where spinal fusion may be considered include the following: *

Degenerative disc disease Degenerative disc disease (DDD) is a medical condition typically brought on by the aging process in which there are anatomic changes and possibly a loss of function of one or more intervertebral discs of the vertebral column, spine. DDD can take ...

Spinal disc herniation A disc herniation or spinal disc herniation is an injury to the intervertebral disc between two vertebrae, usually caused by excessive strain or trauma to the spine. It may result in back pain, pain or sensation in different parts of the body, ...

* Discogenic pain * Spinal

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

* Vertebral fracture *

Scoliosis Scoliosis (: scolioses) is a condition in which a person's Vertebral column, spine has an irregular curve in the coronal plane. The curve is usually S- or C-shaped over three dimensions. In some, the degree of curve is stable, while in others ...

Kyphosis Kyphosis () is an abnormally excessive convex curvature of the Spinal column, spine as it occurs in the Thoracic spine, thoracic and sacrum, sacral regions. Abnormal inward concave ''lordotic'' curving of the Cervical spine, cervical and Lumba ...

(e. g., Scheuermann's disease) * Lordosis *

Spondylolisthesis Spondylolisthesis is when one spinal vertebra slips out of place compared to another. While some medical dictionaries define spondylolisthesis specifically as the forward or anterior displacement of a vertebra over the vertebra inferior to it (o ...

Spondylosis Spondylosis is the degeneration of the vertebral column from any cause. In the more narrow sense, it refers to spinal osteoarthritis, the age-related degeneration of the spinal column, which is the most common cause of spondylosis. The degener ...

* Posterior rami syndrome * Other degenerative spinal conditions * Any condition that causes instability of the spine

Contraindications

Bone morphogenetic protein Bone morphogenetic proteins (BMPs) are a group of growth factors also known as cytokines and as metabologens. Professor Marshall Urist and Professor Hari Reddi discovered their ability to induce the formation of bone and cartilage, BMPs are now ...

(rhBMP) should not be routinely used in any type of anterior cervical spine fusion, such as with

anterior cervical discectomy and fusion Anterior cervical discectomy and fusion (ACDF) is a surgical procedure to treat nerve root or spinal cord compression by decompressing the spinal cord and nerve roots of the cervical spine with a discectomy, followed by inter-vertebral fusion to ...

., which cites * * There are reports of this therapy causing

soft tissue Soft tissue connective tissue, connects and surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, Adipose tissue, fat, fibrous tissue, Lymphatic vessel, lymph and blood vessels, fasciae, and synovial membranes.� ...

swelling, which in turn can cause life-threatening complications due to difficulty swallowing and pressure on the

respiratory tract The respiratory tract is the subdivision of the respiratory system involved with the process of conducting air to the alveoli for the purposes of gas exchange in mammals. The respiratory tract is lined with respiratory epithelium as respirato ...

Epidemiology

According to a report by the Agency for Healthcare Research and Quality (AHRQ), approximately 488,000 spinal fusions were performed during U.S. hospital stays in 2011 (a rate of 15.7 stays per 10,000 population), which accounted for 3.1% of all operating room procedures. This was a 70 percent growth in procedures from 2001. Lumbar fusions are the most common type of fusion performed ~ 210,000 per year. 24,000 thoracic fusions and 157,000 cervical fusions are performed each year. A 2008 analysis of spinal fusions in the United States reported the following characteristics: * Average age for someone undergoing a 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 * 45.5% of all spinal fusions were on men * 83.8% were white, 7.5% black, 5.1% Hispanic, 1.6% Asian or Pacific Islander, 0.4% Native American * Average length of hospital stay was 3.7 days – 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%

Effectiveness

Although spinal fusion surgery is widely performed, there is limited evidence for its effectiveness for several common medical conditions. For example, in a

randomized controlled trial A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical ...

of Swedish adults with spinal stenosis, after 2 and 5 years, there were no significant clinical benefits of lumbar fusion in combination with decompression surgery in comparison to decompression surgery alone. The study enrolled 247 patients from 2006 to 2012 and further found increased medical costs for those who received fusion surgery as a result of increased surgery time, hospital stay duration, and cost of the implant.

Technique

There are many types of spinal fusion techniques. Each technique varies depending on the level of the spine and the location of the compressed spinal cord/nerves. After the spine is decompressed,

bone graft Bone grafting is a type of transplantation used to replace missing bone tissue or stimulate the healing of fractures. This surgical procedure is useful for repairing bone fractures that are extremely complex, pose a significant health risk to the ...

or artificial bone substitute is packed between the vertebrae to help them heal together. In general, fusions are done either on the anterior (stomach), posterior (back), or both sides of the spine. Today, most fusions are supplemented with hardware (screws, plates, rods) because they have been shown to have higher union rates than non-instrumented fusions. Minimally invasive techniques are also becoming more popular. These techniques use advanced image guidance systems to insert rods/screws into the spine through smaller incisions, allowing for less muscle damage, blood loss, infections, pain, and length of stay in the hospital. The following list gives examples of common types of fusion techniques performed at each level of the spine: ACDF surgery english

Cervical spine

Anterior cervical discectomy and fusion Anterior cervical discectomy and fusion (ACDF) is a surgical procedure to treat nerve root or spinal cord compression by decompressing the spinal cord and nerve roots of the cervical spine with a discectomy, followed by inter-vertebral fusion to ...

(ACDF) * Anterior cervical corpectomy and fusion * Posterior cervical decompression and fusion

Thoracic spine

* Anterior decompression and fusion * Posterior instrumentation and fusion – many different types of hardware can be used to help fuse the thoracic spine including sublaminar wiring, pedicle and transverse process hooks, pedicle screw-rod systems, vertebral body plate systems.

Lumbar spine

* Posterolateral fusion is a bone graft between the

transverse process Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

es in the back of the spine. These 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 Fusion is a graft where the entire

intervertebral disc An intervertebral disc (British English), also spelled intervertebral disk (American English), lies between adjacent vertebrae in the vertebral column. Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the ver ...

between vertebrae is removed and a bone graft is placed in the space between the

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

. A plastic or titanium device may be placed between the vertebra to maintain spine alignment and disc height. The 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

Risks

Spinal fusion is a high risk surgery and complications can be serious, including death. In general, there is a higher risk of complications in older people with elevated body mass index (BMI), other medical problems, poor nutrition and nerve symptoms (numbness, weakness, bowel/bladder issues) before surgery. Complications also depend on the type/extent of spinal fusion surgery performed. Smokers and people who are Vitamin D deficient are at a higher risk of spinal fusion failure. There are three main time periods where complications typically occur:

During surgery

* Patient positioning on operating table * Blood loss * Damage to nerves and surrounding structures during procedure * Insertion of spinal hardware ** Conventional Pedicle screws increased the risk of failure compared to Expandable Pedicle screws * Harvesting of bone graft (if autograft is used) * Patients who used the allograft were at a higher risk of fusion failure.

Within a few days

* Moderate to severe postoperative pain * Wound infections - risk factors include old age, obesity, diabetes, smoking, prior surgery *

Deep vein thrombosis Deep vein thrombosis (DVT) is a type of venous thrombosis involving the formation of a blood clot in a deep vein, most commonly in the legs or pelvis. A minority of DVTs occur in the arms. Symptoms can include pain, swelling, redness, and enl ...

(DVT) *

Pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain ...

(PE) *

Urinary retention Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include urinary incont ...

Malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues a ...

* Neurologic deficit * Shock, sepsis and cerebrovascular infarction

Weeks to years following surgery

* Infection – sources of bacterial bioburden that infiltrate the wound site are several, but the latest research highlights repeated reprocessing of implants before surgery and exposure of implants (such as pedicle screws) to bacterial contaminants in the "sterile-field" during surgery as major risk factors. * Deformity – loss of height, alignment, and failure of fusion *

Pseudarthrosis Nonunion is permanent failure of healing following a broken bone unless intervention (such as surgery) is performed. A fracture with nonunion generally forms a structural resemblance to a fibrous joint, and is therefore often called a "false j ...

– nonunion between fused bone segments. Risk factors include tobacco use,

nonsteroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a Indication (medicine), therapeutic drug class which Analgesic, reduces pain, Anti-inflammatory, decreases inflammation, Antipyretic, decreases fever, and Antithrombotic, prevents bl ...

use, osteoporosis, revision procedures, decreased immune system. * Adjacent segment disease – degeneration of vertebrae above/below the fused segments due altered biomechanical stresses or patient propensity to develop progressive degenerative change. * 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

Recovery following spinal fusion is extremely variable, depending on individual surgeon's preference and the type of procedure performed. The average length of hospital stay for spinal fusions is 3.7 days. Some patients can go home the same day if they undergo a simple cervical spinal fusion at an outpatient surgery center. Minimally invasive surgeries are also significantly reducing the amount of time spent in the hospital. Recovery typically involves both restriction of certain activities and rehabilitation training. Restrictions following surgery largely depend on surgeon preference. A typical timeline for common restrictions after a lumbar fusion surgery are listed below: * 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. There is some evidence that it improves functional status and low back pain so some surgeons may recommend it.

Usage

According to a report by the Agency for Healthcare Research and Quality (AHRQ), approximately 488,000 spinal fusions were performed during U.S. hospital stays in 2011, a rate of 15.7 stays per 10,000 population, which accounted for 3.1% of all operating room procedures.

Public health hazard

In 2019, the news channel WTOL-TV broadcast an investigation, "Surgical implants raising contamination concerns", uncovering a dossier of scientific evidences that current methods of processing and handling spinal implants are extremely unhygienic and lacks quality control. This lack of quality control is exposing patients to high risk of infection, which themselves are underreported given the long time frame (0–7 years) and reportedly lack follow up data on the patients undergoing spine surgery. A petition was filed by the lead investigator, Aakash Agarwal, to rectify this global public health hazard of implanting contaminated spinal devices in patients.

References

External links

* Wheeless, C. R., et al., Eds
Fusion of the Spine.
''Wheeless' Textbook of Orthopaedics''. Division of Orthopedic Surgery. Duke University Medical Center.
Spinal Fusion.
American Academy of Orthopaedic Surgeons. June 2010. Accessed 1 June 2013. * Spinasanta, S
What is Spinal Instrumentation and Spinal Fusion?
SpineUniverse. September 2012. Accessed 1 June 2013.

Encyclopedia of Surgery. Accessed 1 June 2013. {{Operations and other procedures on the musculoskeletal system Neurosurgical procedures Orthopedic surgical procedures