What is the difference between Ponte (posterior osteotomy) and Smith-Petersen (lumbosacral osteotomy) osteotomies in spinal deformity correction?

Differences Between Ponte and Smith-Peterson Osteotomies in Spinal Deformity Correction

Ponte osteotomy (complete facet resection) and Smith-Petersen osteotomy (partial facetectomy) are both posterior column shortening osteotomies that differ primarily in the extent of bone resection, with Ponte being more extensive and providing greater correction per level.

Anatomical Differences

Smith-Petersen Osteotomy (SPO)

• Involves partial facetectomy (Schwab-grade-I posterior column osteotomy)
• Posterior ligaments and facet joints are removed
• Correction is performed through the disc space
• Requires a mobile anterior disc to achieve correction
• Acts as a posterior column shortening procedure

Ponte Osteotomy (PO)

• Involves complete facet resection (Schwab-grade-II posterior column osteotomy)
• More extensive bone removal compared to SPO
• Includes complete removal of the spinous process, lamina, and facet joints
• Provides greater correction per level than SPO

Correction Capability

Smith-Petersen Osteotomy

• Provides approximately 9.3° to 10.7° correction per level 1
• Correction rate of approximately 1° per mm of bone removed
• Best for patients with +6-8 cm C7 plumbline sagittal imbalance 1
• Less powerful than Ponte osteotomy

Ponte Osteotomy

• Provides greater correction per level than SPO
• Major curve correction rate of approximately 57.40% compared to 49.19% with SPO 2
• Can be performed at multiple levels for cumulative correction

Clinical Applications

Smith-Petersen Osteotomy

• Ideal for:
  • Degenerative sagittal imbalance
  • Mild to moderate deformities
  • Patients with mobile disc spaces
  • Multiple level correction needs

Ponte Osteotomy

• Ideal for:
  • More rigid deformities
  • Cases requiring greater correction per level
  • Ankylosing spondylitis with kyphosis
  • When SPO would be insufficient

Risks and Complications

Comparative Risks

• Both procedures show comparable overall immediate postoperative complication rates (28.57% for SPO vs 29.41% for PO) 2
• Neurological deficits at 2+ years follow-up:
  • SPO: 0%
  • PO: 14.28% (higher long-term neurological risk) 2

Important Considerations

• Patients with pre-existing neurological deficits are at higher risk of sustaining neurological morbidity following corrective surgery 2
• Disability outcomes (ODI scores) at 2+ years are significantly better in SPO-treated patients 2

Hierarchy of Spinal Osteotomies

In the spectrum of spinal osteotomies, from least to most aggressive:

1. Smith-Petersen/Ponte osteotomies (posterior column)
2. Pedicle subtraction osteotomy (PSO) - provides 30-40° correction per level
3. Bone-disc-bone osteotomy (BDBO) - provides 35-60° correction
4. Vertebral column resection (VCR) - most aggressive, for severe multi-planar deformities

Clinical Decision Making

When choosing between SPO and Ponte osteotomy:

• Consider the degree of correction needed
• Evaluate the rigidity of the deformity
• Assess patient's baseline neurological status
• Weigh the risk-benefit profile based on patient factors

Surgical Considerations

• Both procedures should be performed by experienced spine surgeons
• For severe kyphosis in ankylosing spondylitis, spinal osteotomy should only be considered in highly selected patients who lack horizontal vision causing major physical and psychological impairments 3, 4
• Such procedures should be performed at specialized centers by surgeons with extensive experience 3

Cautions

• Spinal manipulation with high-velocity thrusts should be avoided in patients with spinal fusion or advanced spinal osteoporosis due to risk of severe complications 4
• Elective spinal osteotomy carries significant risks including 4% perioperative mortality and 5% permanent neurologic sequelae in ankylosing spondylitis patients 3, 4