Spinal fusion is a surgical procedure to treat pain, instability, or deformity in the spine by fusing two or more bones so they heal into one solid bone. While spinal fusion can help some people feel better, it may not remove all symptoms, and recovery can take several months to a year. Doctors usually recommend trying other approaches before considering this surgery.

Spinal fusion is a surgical procedure that connects two or more vertebrae to form a single solid bone. The goal of the procedure is to support the spine and reduce pain by stopping movement between the fused bones. This operation can be performed on the neck, upper, or lower sections of the spine and may be considered when other treatments do not provide relief from symptoms, such as pain, stiffness, and restricted movement.

In spinal fusion, the surgeon joins bones together using synthetic materials or bone from another area of the patient’s body or from a donor. The surgeon commonly uses other devices, such as rods, screws, plates, or cages, to keep the bones steady during healing.

Most spinal fusions involve only a small part of the spine, and for many people the procedure does not result in a major loss of movement. However, some loss of flexibility is possible. The impact of the surgery on mobility depends on the location and extent of the fusion.

Doctors may recommend spinal fusion to treat several conditions that affect the spine when other treatments do not relieve symptoms. These conditions include:

• Spinal stenosis, in which the spinal canal narrows and puts pressure on the spinal cord and nerve roots, causing pain, numbness, and other symptoms
• Spondylolisthesis, where a vertebra slips forward and causes instability, nerve pressure, and pain
• Abnormal spinal curves, such as scoliosis (a sideways curve that also twists abnormally) or kyphosis (a forward curve of the upper spine that causes a hunched back) that affect posture or cause pain
• Herniated (ruptured) or slipped discs that do not improve with other treatments (a disc is a rubbery pad between the vertebrae that absorbs shock and allows movement)
• Degenerative disc disease, in which discs become damaged over time, leading to pain and stiffness
• Fractures or injuries to the spine that cannot be treated with less invasive procedures
• Arthritis in the spine, which can cause pain, inflammation, and stiffness
• Tumors or infections that can weaken bones

Doctors may also suggest other procedures at the same time as spinal fusion, such as removing bone or tissue that is pressing on nerves.

Before recommending spinal fusion, the doctor will review medical history and perform a physical exam to assess symptoms and overall health. They will also order one or more tests to assess spinal health and identify the source of symptoms.

Common tests used before spinal fusion include:

• X-rays of the spine’s bones to show alignment, fractures, or abnormal curves
• Computed tomography (CT) scans to provide detailed pictures of the spine’s structure and help identify bone problems
• Magnetic resonance imaging (MRI) scans to show soft tissues, such as discs and nerves, as well as nerve compression and injury
• Lab tests, including blood tests, to check for infection, bleeding problems, or other health concerns

Doctors may also ask about current medicines, allergies, and any past surgeries to help plan the procedure safely.

Candidates for spinal fusion include people with spine problems that have not improved with other treatments, such as physical therapy or medications. People who undergo spinal fusion usually have pain, instability, or nerve symptoms caused by conditions like spinal stenosis, spondylolisthesis, abnormal curves, fractures, or arthritis.

Doctors consider several factors when deciding if spinal fusion is appropriate:

• Overall health, including any medical conditions like diabetes or heart disease
• Severity and location of spine problems
• Response to previous treatments
• Symptoms such as pain, numbness, or weakness that affect daily life

Spinal fusion is not recommended for everyone. Doctors carefully weigh the risks and benefits for each person.

Preparation for spinal fusion depends on the individual's health and the type of surgery planned. Having realistic expectations and a good understanding of the surgery and the recovery process will help with preparation.

Taking the following steps before surgery can help improve outcomes:

• Discuss all medications with the doctor, including prescription and over-the-counter medicine and herbal supplements. Some medicines may need to be stopped before surgery, especially those that affect bleeding.
• Inform the doctor about any allergies, bleeding problems, or recent illnesses, such as colds or infections. Surgery may be delayed if there is an active infection.
• Quit smoking or cut back to improve bone healing and reduce risks, since smoking can delay healing.
• Manage other health conditions, such as diabetes or heart disease, by seeing the appropriate health care providers.
• Follow instructions about not eating or drinking for a certain period before surgery.
• Use special soap or cleaning methods the day before surgery (or as instructed) to lower the risk of infection.
• Prepare for recovery by arranging a ride home after surgery and help with daily tasks.

People should ask questions if they are unsure about any instructions and make sure they understand what to expect before, during, and after surgery.

Spinal fusion surgery usually takes several hours, depending on the complexity and number of vertebrae being fused. In some cases, the surgeon may choose to use minimally invasive techniques, which involve smaller incisions and may help with faster recovery.

Based on the location of the surgery and other factors, the surgeon will select an approach—front (anterior), back (posterior), or side (lateral). Once the individual is asleep under general anesthesia, the surgeon will then make an incision and carefully move tissues aside to access the spine. Before fusing the vertebrae, the surgeon will sometimes remove tissue or bone pressing on nerves.

To fuse the bones, the surgeon places a bone graft between or over the vertebrae to help them grow together. A bone graft is bone or bone-like material that is used to help the vertebrae fuse. The bone graft can come from:

• The person’s own body, often from the hip (autograft)
• A donor, using bone from a bone bank (allograft)
• Artificial materials, such as synthetic bone or growth factors

The surgeon commonly uses certain devices—including special cages, screws, rods, or plates—to hold the bones in place while they heal. These devices provide stability and help the fusion process.

After the bone graft and hardware are in place, the surgeon closes the incision and covers it with bandages. Sometimes, they will place a temporary drain tube to remove extra fluid or blood.

Spinal fusion has risks and possible complications, as with any surgery. Doctors discuss these risks before the procedure and take steps to reduce them.

Risks of spinal fusion include:

• Infection
• Bleeding or blood clots
• Injury to nerves or the spinal cord
• Spinal fluid leaks
• Bones not fusing
• Hardware problems
• Persistent pain or stiffness, or recurrence of symptoms
• New disc problems near the fusion

In addition, any surgery under general anesthesia carries a small risk of stroke, heart attack, swallowing or voice changes, hernia, or death.

People should contact a health care provider or seek emergency care if they notice warning signs of complications, including:

• Redness, swelling, or drainage from the incision
• Fever above 100.4°F (38°C) or shaking chills
• Redness, swelling, or pain in the calf or lower leg
• Sudden chest pain, shortness of breath, or coughing
• New or worsening pain, weakness, or numbness in the legs, or problems standing, walking, or moving
• Problems with urination or bowel movements
• Severe headache or persistent nausea and vomiting

Doctors will explain which symptoms need urgent attention and when to call for help.

Recovery after spinal fusion takes time and can vary based on the type of surgery and the person’s overall health. Most people stay in the hospital for one to three days after surgery. Pain is common, and doctors use medicines to help manage it. Most people are no longer taking pain medications by two to three weeks after surgery.

After spinal fusion, patients learn safe ways to move, such as getting in and out of bed without twisting their back. Physical therapy is often started a few weeks later to help build strength and support healing.

A brace may be recommended to support the spine while it heals. People should avoid bending, twisting, or lifting heavy objects until the doctor says it is safe. The health care team will provide advice on when and how to increase activity.

The health care team will give instructions for how to take medications and care for the wound.

The fusion process may take several months, and many people notice improvement in comfort before the bones are fully healed. Follow-up appointments allow doctors to remove stitches or staples and check progress.

The outlook for people undergoing spinal fusion surgery depends on their overall health, the reason for surgery, and how well the bones heal. Most people experience relief from pain and improved function. Spinal fusion does not always eliminate all pain, especially if the patient had chronic pain before surgery. Doctors cannot always know in advance how much a person will improve after spinal fusion, even with imaging studies. Maintaining a healthy lifestyle, losing weight, and exercising can increase the chances of feeling better.

Future spine problems may develop, especially in areas above or below the fusion. Doctors monitor recovery and provide guidance to help achieve the best possible outcome. Many people return to most of their usual activities as they recover. The time needed for full recovery can vary, and for some people, it may take several months or up to a year.

“At Yale Medicine, our spine surgeons provide an individualized treatment plan for every patient based on history, physical exam, and advanced imaging results,” says Yale Medicine orthopaedic spine surgeon Daniel Rubio, MD, co-director of the Spine Center at Yale New Haven Hospital. “We provide guidance on surgical and nonsurgical techniques for all problems within the spine.”

When surgery is recommended, Dr. Rubio adds, Yale offers some of the most advanced techniques and procedures in the region, like intra-operative navigation and robotic-assisted surgery, endoscopic spine surgery, and minimally-invasive spinal fusion procedures, including lateral interbody fusion and minimally-invasive transforaminal lumbar interbody fusion.

“Additionally, working closely with spine surgeons and patients, our nurse navigator team helps patients and their families navigate through their surgeries from pre-operative appointment to post-operative care to ensure that they feel comfortable and supported as they recover to return to an active and healthy lifestyle,” he says.