Scoliosis Research Society (SRS)
Scoliosis Research Society (SRS)
An International Organization Dedicated to the Education, Research and Treatment of Spinal Deformity
Our Mission is to Foster Optimal Care for All Patients with Spinal Deformities


Fixed Sagittal Imbalance

Operative Treatment

The decision process for surgery depends on a number of factors: the type of sagittal imbalance, a history of prior surgeries, the degree and location of neural compression, the age and health of the patient, among other things. Instrumentation and osteotomy techniques allow repositioning the spine. Below is a description of the types of spinal osteotomies available:

1. Posterior osteotomy (also called “Smith-Peterson” or “Ponte” osteotomies):
This procedure involves removing the facet joints and interspinous ligaments to tilt the bones posteriorly through a mobile disc space. The facet joints typically limit extension of the spine, so their removal allows the surgeon to accentuate lordosis. Over multiple levels, 5-15o of lordosis per level is possible.

Posterior Osteotomy
Posterior Osteotomy:
A) A side view of the spine showing the bone and facet resection.
B) A side view after the osteotomy is closed.
C) A lateral (side) radiograph of a woman with severe, rigid, Scheurmann’s kyphosis.
D) A lateral xray after surgery. Multi-level posterior osteotomies allowed the surgeon to reduce the kyphosis to normal levels.

2. Pedicle subtraction osteotomy:
Surgeons use this procedure to cut through kyphotic segments. We call it a “closing wedge osteotomy” because a triangle of bone is removed so the bone can be angled backwards. The procedure is particularly powerful, especially in the lumbar spine where the bones are bigger, and small corrections can lead to large improvements in posture. It is similar to placing a wedge between bricks – creating a sudden backward bend in the spine. The surgery requires the support of instrumentation above and below the osteotomy.

Pedicle subtraction osteotomy
Pedicle subtraction osteotomy:
A) A side view showing the area of bone resection in pink.
B) The lordotic segment after the osteotomy is closed. Note how the front of the vertebra is twice the height of the back causing lordosis.
C) The preoperative xrays of a patient with fixed sagittal imbalance due to bone settling and infection.
D) A lateral (side) xray showing the restored lordosis after the osteotomy.

3. Vertebral column resection:
This is the most powerful procedure of all spinal osteotomies. It is necessary when there is a severe bend in a small area. It involves essentially dislocating the spine in a controlled manner and realigning it in the proper direction.

Vertebral column resection
Vertebral column resection:
A) A side view of the spine showing the additional bone removed beyond a pedicle subtraction osteotomy (added area in blue).
B) A strut graft or cage is placed between the cut vertebra.
C & D) The front and side view of a woman with severe, rigid kyphoscoliosis.
E & F) Postoperative front and side xrays after the realignment procedure.

4. Anterior-posterior osteotomy:
At times there is a failed fusion whose motion can be used to restore alignment. This may require an anterior and posterior surgery to take advantage of the motion through the failed fusion or mobile segment.

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