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What Is a Pedicle Subtraction Osteotomy?

Pedicle subtraction osteotomy is a powerful three-column spinal osteotomy used to correct a rigid sagittal deformity. It is commonly abbreviated PSO. The surgeon removes the posterior elements, both pedicles, and a wedge of bone from a vertebral body while keeping the front portion of the vertebra intact as a hinge. Closing the wedge increases lordosis and can bring the upper body backward over the pelvis without lengthening the front of the spine.

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What Is a Pedicle Subtraction Osteotomy?

Pedicle subtraction osteotomy is a powerful three-column spinal osteotomy used to correct a rigid sagittal deformity. It is commonly abbreviated PSO. The surgeon removes the posterior elements, both pedicles, and a wedge of bone from a vertebral body while keeping the front portion of the vertebra intact as a hinge. Closing the wedge increases lordosis and can bring the upper body backward over the pelvis without lengthening the front of the spine.

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Why Is a Pedicle Subtraction Osteotomy Performed?

PSO is used for selected adults with severe fixed sagittal imbalance that cannot be corrected adequately with positioning, disc releases, or less aggressive posterior osteotomies. Common situations include flatback deformity after prior fusion, ankylosed spinal deformity, or major loss of lumbar lordosis that causes forward stooping and difficulty standing upright. The operation can produce a large angular correction at a single vertebral level, often around the lumbar spine. Because the procedure carries substantial blood loss and neurologic risk, it is generally reserved for complex deformities treated by experienced spinal-deformity teams.

How Is a Pedicle Subtraction Osteotomy Performed?

The surgeon approaches the spine from the back and exposes the planned osteotomy level as part of a long instrumented fusion. The posterior elements and pedicles are removed, and a triangular wedge of cancellous bone is taken from the vertebral body while the anterior cortex is preserved as a hinge. The spine is then carefully closed through the osteotomy until the planned sagittal correction is achieved. Pedicle screws and rods above and below the osteotomy stabilize the corrected alignment while fusion develops.

What Is Recovery Like After Pedicle Subtraction Osteotomy?

Recovery is more intensive than after routine lumbar fusion because PSO is commonly part of a large multilevel deformity reconstruction. Patients are monitored for blood loss, neurologic function, wound healing, cardiopulmonary complications, and stability of the long spinal construct. Walking and rehabilitation begin gradually, while lifting, bending, and strenuous activity remain restricted during fusion. Functional improvement and adaptation to the new alignment can continue for many months after the initial hospital recovery.

What Are the Risks and Complications?

PSO has a substantial complication profile that includes major blood loss, infection, blood clots, dural tear, neurologic deficit, and medical complications from prolonged surgery. Nerve-root or spinal-cord injury can occur during wedge closure, particularly if bone, dura, or nerve tissue becomes compressed or buckled. Long-term complications include pseudarthrosis, rod or implant breakage, proximal junctional kyphosis or failure, and loss of correction. Revision surgery can be required when hardware fails, fusion does not heal, or alignment deteriorates.

Frequently Asked Questions About Pedicle Subtraction Osteotomy

How much correction can a pedicle subtraction osteotomy provide?

A lumbar PSO commonly produces roughly 25 to 30 degrees of angular correction at one level, although the exact correction depends on anatomy and the surgical plan.

Why is PSO called a three-column osteotomy?

The osteotomy crosses the posterior elements, middle portion of the vertebra, and vertebral body, allowing a much larger correction than a posterior-column osteotomy alone.

Is pedicle subtraction osteotomy a high-risk surgery?

Yes. It is a complex deformity procedure associated with major blood loss and meaningful neurologic, mechanical, and medical complication risks.

Is PSO commonly performed during revision spine surgery?

Yes. It is frequently used to correct fixed flatback or sagittal imbalance in patients who already have a long spinal fusion.

References

Pedicle Subtraction Osteotomies for Surgical Correction of Fixed Sagittal Imbalance: A Meta-Analysis and Systematic Review. PubMed. https://pubmed.ncbi.nlm.nih.gov/38904379/. Date Accessed September 11, 2026.

Spinal osteotomies: indications, limits and pitfalls. PubMed. https://pubmed.ncbi.nlm.nih.gov/28507779/. Date Accessed September 11, 2026.

Neurologic complications of lumbar pedicle subtraction osteotomy: a 10-year assessment. PubMed. https://pubmed.ncbi.nlm.nih.gov/17873818/. Date Accessed September 11, 2026.

Pedicle Subtraction Osteotomy in the Revision Versus Primary Adult Spinal Deformity Patient: Is There a Difference in Correction and Complications? PubMed. https://pubmed.ncbi.nlm.nih.gov/26730526/. Date Accessed September 11, 2026.

Perioperative Complications of Pedicle Subtraction Osteotomy. PubMed. https://pubmed.ncbi.nlm.nih.gov/27781181/. Date Accessed September 11, 2026.