Spinal Osteotomy

What is it?

A healthy low back curves gently inward. This curve helps you stand upright without effort. In some people, the spine becomes stiff and bent forward. Doctors call this sagittal imbalance. When it happens after an earlier fusion that flattened the low back, it is often called flatback. People with this problem often bend their knees, lean on a cart or cane, or feel tired and sore after standing a short time.

If the spine is flexible, a surgeon can often straighten it with screws and rods alone. If the spine is stiff or already fused, the surgeon may need to remove some bone first. That is an osteotomy. Surgeons grade osteotomies from 1 to 6, from smallest to largest. The main types are:

• Posterior column osteotomy (Smith-Petersen or Ponte). Removes parts of the small joints at the back of the spine. Each level gives about 9 degrees of correction on average. Several levels can be done.
• Pedicle subtraction osteotomy (PSO). Removes a wedge-shaped piece of one vertebra, then closes the gap. Studies report about 27 to 36 degrees of correction at one level.
• Vertebral column resection (VCR). Removes an entire vertebra and its discs. It is used for the most severe, rigid deformities. A review found average corrections of about 59 to 64 degrees.

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

An osteotomy may be an option for adults who:

• have a stiff spine that bends forward or sideways and does not straighten when lying down
• have flatback after an earlier fusion
• have a sharp forward bend (kyphosis), sometimes after a fracture or infection
• have symptoms that limit daily life and have not improved with other care

An osteotomy is usually not needed when:

• the spine is still flexible enough to correct with screws and rods alone
• the deformity is mild or causes few symptoms
• health problems make a long, major surgery too risky

The surgeon usually chooses the smallest osteotomy that can reach the needed correction. Larger osteotomies give more correction but have more complications. In one study of young patients with severe curves, followed for about 9 years, complications occurred in 51.2% of patients after VCR and 34.1% after PSO.

What are the alternatives, including non-surgical care?

Non-surgical care includes physical therapy, pain medicines, injections and treating weak bones. These can ease symptoms, but they do not change the shape of a stiff spine. In studies of adult deformity, non-surgical care usually kept pain and disability about the same over 2 years.

Other surgical options may include a fusion without a large osteotomy, smaller osteotomies at several levels, or correcting the spine through the side or front of the body. Which option fits depends on how stiff the spine is, how much correction is needed, and your health.

What happens before surgery?

Imaging. You will have full-length standing X-rays. These show your whole spine, from neck to hips, while you stand. The surgeon measures how your spine lines up with your pelvis. Key measures include how far your upper body leans forward and how much your pelvis has tilted backward to make up for it. These measures help decide how much correction you need and which osteotomy to use. CT scans and MRI are often needed too.

Correcting too much can also cause problems. In one study, correcting beyond age-based targets was linked to more problems above the fusion, without extra benefit. Evidence note: Ideal targets are still debated and may differ by age.

Bone density, smoking, diabetes and nutrition. These matter a great deal for large spine surgery. A national guideline recommends checking bone health in people at risk for osteoporosis. In one study of complex deformity surgery, 19.2% of smokers had heavy bleeding during surgery, compared with 3.7% of nonsmokers. A national guideline advises extra counseling when HbA1c (a 3-month blood sugar test) is above 7.5%. Your heart, lungs and overall strength will also be checked.

What happens during surgery?

You are fully asleep (general anesthesia) and lie face down. The surgeon makes a cut down the middle of your back. Screws are placed in the vertebrae above and below the osteotomy. The surgeon then removes the planned bone, while protecting the spinal cord and nerves. The spine is carefully moved into its new position and held with rods. Bone graft is added so the bones heal together.

Nerve signals are usually watched during surgery. Osteotomy operations often take many hours. Blood loss can be large: about 2,000 mL on average for a PSO in one review. Most patients need a blood transfusion.

What are the risks?

Large osteotomies (PSO and VCR) are among the most complex spine operations. Complications are common.

• Any complication: In a multicenter study of PSO and VCR, 78% of patients had at least one complication within 2 years. In a French multicenter study, the rate was 59.2%, and only 30% of patients were free of complications at 5 years. Smaller posterior column osteotomies had a complication rate of 24.2%.
• Nerve problems: After PSO in the low back, 11.1% of patients had new nerve problems. They were permanent in 2.8%. In complex deformity surgery, 23% had new leg weakness at hospital discharge, and about 10% still had it at 2 years. Nerve problems were more common after VCR than PSO: 15.5% vs. 8.2%.
• Heavy bleeding: In a study of 423 patients, 24% lost more than 4 liters of blood.
• Tear in the nerve covering (dural tear): Rates range from 10% to 44%. Tears were more likely when the patient had earlier surgery at the same level. Evidence note: Reported rates vary widely between studies.
• Broken rods: In a multicenter study, rods broke in 22% of PSO patients. In one study, adding extra rods lowered the rate from 36.4% to about 13% to 14%.
• Another surgery: 27.5% to 33% of patients needed another operation within about 2 years. In a 10-year study, about half (52.4%) had needed another operation.
• Death: In a study of 1,441 patients, 1.2% died within 30 days. Risk was higher with diabetes, lung disease and frailty.

What is recovery like?

Hospital stay. In a study of 300 patients, average stays ranged from 7.3 days for patients under 50 to 11.0 days for patients 80 and older. Another study reported an average of 8.2 days. Many patients spend 1 to 3 days in intensive care first. Some go to a rehab center before home.

Walking. A therapist helps you get up and walk soon after surgery. Walking is the main exercise early on.

Driving and work. In a study of adults fused to the pelvis, 97.4% returned to driving, on average about 4 months after surgery. Of those who worked, 88% returned, on average about 5.4 months after surgery. Evidence note: This study included deformity fusions in general, not only osteotomies. Do not drive while taking opioid pain medicine.

Final result. In one study, most of the quality-of-life improvement happened in the first 6 months. Results usually stay stable from 2 to 5 years.

What results can patients expect?

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

• In a review of 431 patients who had PSO, average disability scores improved from 50.5 to 32.8 on a 0-to-100 scale. Lower is better.
• In a study that followed PSO patients for at least 5 years, 87% reported being satisfied.
• Results may differ by cause. In one study, patients with flatback after an earlier fusion improved less and needed more repeat surgeries (46%) than patients having their first deformity surgery (25%).
• In one large study, patients who had major complications ended up with similar results at 2 to 5 years as patients who did not. Evidence note: Other studies found smaller benefits after complications.
• In a 10-year study, improvements in disability were still present at 10 years. Evidence note: Long-term studies are small.

Questions to ask your surgeon

• Why does my spine need an osteotomy, rather than screws and rods alone?
• Which type of osteotomy do you recommend, and why that type?
• How much correction do I need, and how did you decide?
• What are my specific risks for nerve problems and heavy bleeding?
• How will my bone density, smoking or blood sugar affect my risk? What should I fix first?
• How long will I be in the hospital, and will I need rehab?
• What signs after surgery mean I should call right away?

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