Influence of Sequential Ponte Osteotomies on the Human Thoracic Spine with a Rib Cage

STUDY DESIGN: Biomechanical cadaveric study.

OBJECTIVES: The purpose of this study was to determine the change in range of motion (ROM) of the human thoracic spine and rib cage due to sequential Ponte osteotomies (POs).

SUMMARY OF BACKGROUND DATA: POs are often performed in deformity correction surgeries to provide flexibility in the sagittal plane at an estimated correction potential of 5° per PO, but no studies have evaluated the biomechanical impact of the procedure on a cadaveric model with an intact rib cage.

METHODS: Seven human thoracic cadavers with intact rib cages were loaded with pure moments in flexion, extension, axial rotation, and lateral bending for five conditions: intact, PO at T9-T10, PO at T8-T9, PO at T7-T8, and PO at T6-T7. Motion of T1, T6, and T10 were measured, and overall (T1-T12) and regional (T6-T10) ROMs were reported for each mode of bending at each condition.

RESULTS: POs increased ROM in flexion both overall (T1-T12) and regionally (T6-T10), although the magnitude of the increase was marginal (<1°/PO). No significant differences were found in axial rotation or lateral bending.

CONCLUSIONS: POs may increase sagittal correction potential before fusion in patients with hyperkyphosis, though more work should be done to determine the magnitude of the changes.

LEVEL OF EVIDENCE: Level V.