Corrective Spinal Osteotomies

What is adult spinal deformity, and why does sagittal balance matter?

In adult deformity, the most important factor is not the curve itself, but the spine’s global alignment—how efficiently the torso can remain upright so you can walk without rapid fatigue.

Adult spinal deformity refers to conditions in which the spine deviates from normal alignment in the coronal (frontal) plane (scoliosis) and/or the sagittal plane (kyphosis or loss of lordosis — “flatback”).

High-quality studies show that symptom severity correlates strongly with sagittal balance. A practical way to evaluate this is the C7 sagittal vertical axis (C7 plumb line) relative to the sacrum: in a well-balanced spine, it typically lies within approximately 5 cm of the posterosuperior corner of the sacrum.

When the torso “falls forward,” the body attempts to compensate with hip and knee flexion and posterior pelvic tilt—strategies that are energy-intensive and often lead to substantial pain and reduced quality of life.

Which symptoms prompt evaluation for surgical correction?

Surgical decisions are not based on X-rays alone. They are based on how much the deformity affects function and whether there are neurological problems.

Common symptoms that warrant evaluation by a specialized deformity team include:

• Persistent back pain that does not improve with targeted, structured conservative care.
• Difficulty standing upright (leaning forward, needing frequent breaks while walking).
• Reduced walking endurance and early fatigue.
• Neurogenic claudication or stenosis symptoms (leg pain/numbness with walking).
• Radicular symptoms (sciatica, weakness, paresthesias).
• Progressive deformity or worsening kyphosis/loss of height.

Surgical correction is considered when the deformity causes clear functional impairment and/or there is neurological compromise from stenosis or nerve compression.

How is the preoperative workup performed, and what imaging is needed?

Adult deformity surgery requires some of the most detailed preoperative planning in spine care. Imaging and measurements define correction targets, osteotomy strategy, and stabilization planning.

Preoperative evaluation typically includes:

• Full-length standing spine radiographs (AP & lateral), with hips/knees extended and feet shoulder-width apart, to assess global alignment.
• Flexion–extension films to assess instability and the “rigidity” of the deformity.
• Side-bending films to estimate flexibility and guide corrective strategy.
• CT for bony anatomy, prior fusion/instrumentation, and arthrodesis planning.
• MRI (or CT myelography in selected cases) to assess stenosis and neural element compression.

In parallel, we perform systematic medical optimization (cardiopulmonary assessment, anemia, osteoporosis, glycemic control, etc.), because deformity correction is major surgery and outcomes are strongly influenced by physiology and bone quality.

Key measurements (C7 SVA, PI, PT, SS, LL) — what do they mean?

Spinopelvic parameters are not “radiology numbers.” They are how we define realistic, patient-specific correction targets that match each person’s biomechanics.

• C7 sagittal vertical axis (SVA): a measure of sagittal balance (how far forward/back the torso is positioned).
• Pelvic incidence (PI): an anatomic pelvic parameter (fixed for each person; it does not change).
• Pelvic tilt (PT): a dynamic “compensation” parameter (how much the pelvis rotates backward to compensate). A common target is < 25°, adjusted to the patient’s profile and goals.
• Sacral slope (SS): the sacral inclination, related to sagittal posture.
• Lumbar lordosis (LL): lumbar curvature. A classic alignment goal is: LL ≈ PI ± 10°.

In a well-balanced spine, the PI–LL relationship helps avoid over- or under-correction. When lumbar lordosis is lost, patients often increase PT (posterior pelvic tilt) to “stand upright,” but that compensation comes at a significant functional cost—ongoing pain and rapid fatigue with walking.

What does “rigid deformity” mean, and why are osteotomies needed?

In adults, deformities are frequently rigid due to degeneration, facet arthropathy, or prior surgery. Meaningful correction often requires a surgical “release.”

When discs, joints, and ligaments lose elasticity, the spine cannot be realigned with instrumentation alone. In those situations, the surgeon creates controlled mobility at strategic points—this is the role of osteotomies.

The choice of level, number, and type of osteotomy depends on:

• where the deformity’s apex and “drivers” are located,
• the magnitude of sagittal and coronal imbalance,
• whether prior fusions are present,
• neural anatomy and safety considerations at the selected levels (cord/conus/roots).

Spinal osteotomy grading — explained in plain language

Grading describes how extensive the bone resection is, and therefore how much correction can be achieved — with increasing complexity and risk as the osteotomy becomes larger.

Classification systems categorize osteotomies from smaller posterior releases to resection of an entire spinal segment. In adult rigid deformity, the most commonly referenced “classic” osteotomies include:

• Grade 2 – Ponte (multi-level posterior column releases)
• Grade 3 – PSO (Pedicle Subtraction Osteotomy — a closing-wedge osteotomy through the vertebral body)
• Grade 5 – VCR (Vertebral Column Resection — resection of a vertebral segment)

What is a Ponte osteotomy (Grade 2), and when is it preferred?

A Ponte osteotomy is a multi-segment technique used to achieve gradual improvement in lordosis/kyphosis, typically in milder or more flexible deformities.

A Ponte osteotomy (multi-level wedge osteotomy) involves removal of posterior elements and facets, allowing correction through controlled compression posteriorly and opening anteriorly across the disc spaces (without cutting the anterior longitudinal ligament).

What does it offer?

• On average, ~5–10° of lordotic correction per level.
• Useful for mild-to-moderate sagittal imbalance and/or relatively flexible deformities.
• Often combined with other techniques when a larger correction is needed.

Ponte osteotomies can provide a smooth, harmonious change in spinal curvature because correction is distributed across multiple levels. However, they are generally not the best option for very large, sharp, or highly rigid deformities requiring substantial angular correction.

What is a Pedicle Subtraction Osteotomy (PSO, Grade 3), and when is it preferred?

A PSO is designed for large, focal correction of sagittal imbalance, without requiring anterior column lengthening.

A Pedicle Subtraction Osteotomy (PSO) is a closing-wedge osteotomy that includes posterior elements, pedicles, and a portion of the vertebral body. When the osteotomy is closed, it can create a substantial increase in lordosis.

What does it offer?

• Often ~30–35° of additional lumbar lordosis at a single level (depending on technique and target).
• Highly effective for significant sagittal imbalance and rigid deformity.
• Favorable “biologic” closure profile, as it achieves direct bony contact that supports fusion.

Where is it typically performed?

Levels such as L2–L3 are commonly selected, allowing robust fixation above and below the osteotomy to enable correction while maintaining stability.

PSO is technically demanding and may involve significant blood loss and complications; it therefore requires an experienced team, careful preoperative preparation, and strict safety protocols.

What is a Vertebral Column Resection (VCR, Grade 5), and when is it preferred?

A VCR is the most extensive corrective technique, reserved for severe, rigid, complex multi-planar deformity that cannot be adequately corrected by other methods.

Vertebral Column Resection (VCR) involves removal of a vertebra (and, in exceptional cases, more than one) along with adjacent discs—typically at the apex of the deformity. Correction is achieved through controlled rod contouring and compression, and often requires anterior column reconstruction (e.g., a cage/mesh device).

What does it offer?

• Potential for very large corrections (up to ~60° in selected cases).
• Ability to translate and derotate the spinal axis in highly complex deformities.
• A solution for severe, rigid, sharp deformities and other highly complex scenarios.

Because VCR is among the most demanding operations in spine surgery, it carries an increased risk of neurological complications and requires strict safety protocols and continuous intraoperative neuromonitoring.

What are the risks/complications, and how do we minimize them at Neuroknife?

The larger the osteotomy, the greater the potential correction—but also the higher the potential risk. Modern deformity surgery relies on systematic strategies to reduce these risks.

Main categories of risk include:

• Neurological complications (especially with larger osteotomies such as VCR/PSO).
• Blood loss and need for transfusion.
• Dural tear, particularly in revision surgery.
• Infection, thromboembolic events, and pulmonary complications.
• Nonunion (pseudarthrosis) or hardware failure (especially with poor bone quality/osteoporosis).

How we reduce risk (examples):

• Continuous intraoperative neuromonitoring (SSEP/MEP) in deformity surgery.
• Appropriate decompression/laminectomy when indicated.
• Stable anterior column reconstruction (when needed) to avoid excessive shortening and neural “buckling.”
• Blood management protocols (cell-saver, antifibrinolytics, optimized anesthetic strategy).
• Bone quality optimization (osteoporosis evaluation/treatment) and individualized implant selection.

The safest operation is the one with the right indication and the right target. For that reason, decisions are made only after a full analysis of spinopelvic parameters and the patient’s overall clinical profile.

What to expect during recovery, and which factors influence outcomes?

Recovery after deformity correction is a long process. Structured rehabilitation is part of the treatment—not an afterthought.

It typically includes:

• Hospitalization with gradual mobilization under physiotherapy guidance.
• Emphasis on early mobilization to reduce complication risk.
• Stepwise return to daily activities, with clear early restrictions on bending and heavy lifting.
• Scheduled follow-up visits with imaging to confirm stability and fusion progression.

Factors that influence outcomes include:

• The degree of preoperative sagittal imbalance and the ability to achieve planned correction.
• Bone quality (osteoporosis, nutrition) and adherence to rehabilitation instructions.
• Presence of stenosis/neurological symptoms and improvement after decompression.
• Smoking (increases nonunion risk) and other health factors.