Sagittal Correction and Reciprocal Changes After Thoracic Pedicle Subtraction Osteotomy

Area of Science:

• Spine surgery
• Orthopedics
• Deformity correction

Background:

• Thoracic pedicle subtraction osteotomy (PSO) is a complex procedure for fixed thoracic deformities.
• Anatomical differences exist between upper and lower thoracic PSOs, impacting corrective potential.
• Limited literature addresses the relationship between osteotomy level and adjacent curve changes.

Purpose of the Study:

• Evaluate the sagittal correction efficacy of thoracic PSO.
• Determine how upper versus lower thoracic PSO affects cervical and lumbar spine segments.
• Predict postoperative changes in mobile unfused segments following thoracic PSO.

Main Methods:

• Retrospective clinical review of patients with fixed thoracic kyphotic deformity.
• Data collected from a single institutional database, including medical records and imaging.
• Analysis of patients undergoing single-level thoracic PSO.

Main Results:

• Seventeen patients (11 male, 6 female) with a mean age of 44 years were included.
• Mean follow-up was 55 months; 59% had prior spine surgery.
• Upper thoracic PSO (T1-T6) corrected kyphosis by 31°, lower thoracic PSO (T7-T12) by 41°.
• Upper PSO improved cervical lordosis (mean C7 slope correction 28°), while lower PSO improved lumbar lordosis (mean 22°).

Conclusions:

• Thoracic PSO effectively restores sagittal balance in fixed thoracic deformities.
• The level of thoracic PSO influences compensatory changes in adjacent mobile curves.
• Correction of thoracic kyphosis reduces the need for compensatory lordosis in the cervical and/or lumbar spine.