Revision Spinal Fusion

What is it?

A spinal fusion joins two or more spine bones (vertebrae) so they heal into one solid piece. Most fusions do well. But sometimes a new or ongoing problem leads to another operation. In a landmark study of nearly 25,000 people, 19% had another spine operation within 11 years after low-back surgery for wear-and-tear conditions.

The main reasons for revision are:

• Nonunion (pseudarthrosis). The bones did not heal together. In one study of more than 76,000 patients with a fusion of several low-back levels, 2.7% were diagnosed with a nonunion that caused symptoms within 10 years. Evidence note: Studies define and measure nonunion differently, so reported rates vary widely.
• Adjacent segment disease. The level just above or below a fusion wears out. In one 10-year study after a single-level fusion, wear showed up on X-rays in 75% of patients. But only 31% had symptoms, and 15% needed more surgery.
• Proximal junctional kyphosis (PJK). After a long fusion for scoliosis or a forward-bent spine, the spine just above the rods can bend forward. A review of 8,367 patients found this in 31.65%, with a more serious form (failure) in 11.41%. Most cases show up within 2 years.
• Implant failure. Screws can loosen, or rods can break. This often happens when bone has not healed.

Revision surgery may remove or replace hardware, fix a nonunion, extend the fusion to more levels, or realign the spine.

Who might need it, and who usually doesn't?

Revision may be an option when:

• a clear problem on imaging matches your symptoms
• pain, leg symptoms, weakness or a forward lean keep getting worse
• non-surgical care has not helped enough
• hardware is broken or loose and causing problems

Revision is usually not recommended when:

• X-rays show a change, but you have few or no symptoms. As the study above shows, many X-ray changes never need surgery.
• the cause of pain is not clear
• an infection has not been ruled out or treated first
• health problems make another major surgery too risky

What are the alternatives, including non-surgical care?

Many patients start with physical therapy, medicines and injections. For adjacent segment disease, non-surgical care is often tried first. Surgery is saved for symptoms that do not get better.

Some patients may be candidates for smaller operations. For example, a review of 928 patients found that an endoscopic ("keyhole") procedure for adjacent segment disease had a complication rate of 4.02%. Evidence note: These studies are small, and these procedures are not right for patients with unstable spines or large deformities.

What happens before surgery?

Finding the cause. This is the key step. You will likely need full-length standing X-rays, which show your whole spine from neck to hips while you stand. A CT scan (a detailed 3-D X-ray) is the standard test to check whether a fusion has healed. An MRI may show nerve pressure.

Checking for infection. A hidden infection can cause a fusion to fail. Your doctor may order blood tests. In one study, 9.3% of revision patients with no signs of infection had bacteria on their removed hardware. Evidence note: Standard blood tests can miss these infections.

Bone density. Weak bones can cause screws to loosen. In one study of patients 50 and older having a low-back fusion, about 40% had osteoporosis. A national guideline recommends checking bone health in people at risk.

Smoking, diabetes and nutrition. Smoking is a known risk factor for bones not healing. A national guideline advises extra counseling when HbA1c (a 3-month blood sugar test) is above 7.5%. Low blood protein (albumin below 3.5 g/dL) raises the risk of infection and poor healing.

What happens during surgery?

You are fully asleep (general anesthesia). The surgeon usually opens through the old scar. Scar tissue from the first surgery is carefully removed. Old screws and rods may be checked, removed or replaced. Bone graft is added where bones did not heal. The fusion may be extended to more levels.

Some patients also need an incision on the side or front of the body to fuse the discs. Others need an osteotomy, where bone is removed to realign the spine (see the spinal osteotomy guide). Nerve signals are often watched during surgery. Revision operations can take longer than first surgeries.

What are the risks?

Revision surgery generally carries more risk than a first fusion.

• Overall complications: In a national study of adult deformity surgery, complications occurred in 71.97% of revision cases, compared with 46.96% of first surgeries. Evidence note: Another large study found no difference in 30-day complications after accounting for patient differences. Revision risks may show up later than 30 days.
• Tear in the nerve covering (dural tear): This happened in 15.9% of revision cases, compared with 7.6% of first surgeries. Most tears are repaired during surgery.
• Infection: In adult deformity surgery, revision patients had about 3 times the odds of infection.
• Nerve injury: In a national study, revision patients had about twice the odds of nerve-related complications, including dural tears.
• Another revision: In 4,671 low-back fusions, 13.7% of revision patients needed another revision, compared with 9.71% after a first surgery.
• Death in the hospital: In a large national study of single-level fusions, this was 0.2% after revision.

What is recovery like?

Hospital stay. For revision adult deformity surgery, the average stay was 7.13 days. Smaller revisions often have shorter stays. In one study of revision low-back fusion, stays averaged about 2 to 4 days.

Walking. A therapist helps you get up and walk soon after surgery.

Return to work. After revision for adjacent segment disease, patients returned to work at a median of 2 months. After revision for nonunion, the median was 4 months. Do not drive while taking opioid pain medicine.

Final result. Most improvement happens in the first year. After low-back surgery, patient-reported results usually stop changing much after 1 year.

What results can patients expect?

Results vary from person to person. No one can promise a specific result.

• Results depend on the reason for revision. Meaningful improvement in disability was reached by 49% of patients revised after an earlier decompression, 38% revised for adjacent segment disease, and 29% revised for nonunion.
• In another study, 52% to 65% of revision patients reached a meaningful improvement at 1 year, but fewer than half reached a level of symptoms they considered acceptable.
• In adult deformity, revision patients had about the same chance of meaningful improvement as first-time patients (36.3% vs. 38.3% for disability). But they started and finished with more disability.
• Results tend to get worse with each added revision.

Evidence note: Most revision studies look back at past patients rather than following them forward. Results differ across studies.

Questions to ask your surgeon

• What exactly do you think caused my first surgery to fail, and how sure are you?
• Have you ruled out infection? Do I need a CT scan or other tests?
• Will you need to remove or replace my old hardware? Will the fusion be extended?
• How does my bone density, smoking or blood sugar affect my risk? What should I fix first?
• What is a realistic goal for my pain and function?
• What non-surgical or smaller options do I still have?
• What happens if this revision does not work?

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