Thoracic transfacet pedicle screw fixation: a new instrumentation technique

Area of Science:

• Orthopedic Surgery
• Spine Biomechanics
• Surgical Techniques

Background:

• Pedicle screw fixation (PSF) in the thoracic spine presents significant technical challenges.
• Alternative fixation methods like transverse process and costotransverse screw techniques exist.
• Thoracic transfacet PSF is a novel technique requiring biomechanical evaluation.

Purpose of the Study:

• To introduce and biomechanically evaluate thoracic transfacet pedicle screw fixation (PSF).
• To compare the short-term cyclic loading performance of transfacet PSF against standard PSF.
• To assess the biomechanical equivalence of these two thoracic spine fixation methods.

Main Methods:

• Cadaveric thoracic spine specimens were tested intact under cyclic loading (flexion, extension, lateral bending).
• Specimens were then instrumented with either standard PSF or transfacet PSF and retested.
• Load-to-failure testing in flexion was performed, with stiffness and failure loads analyzed.

Main Results:

• Both standard PSF and transfacet PSF constructs significantly increased construct stiffness compared to intact specimens.
• No statistically significant differences were found between standard PSF and transfacet PSF in stiffness or load-to-failure.
• The T7-T9 spinal region demonstrated lower biomechanical strength in flexion post-instrumentation.

Conclusions:

• Thoracic transfacet PSF demonstrates comparable short-term biomechanical performance to conventional PSF.
• Transfacet PSF may be a suitable alternative to standard PSF in specific thoracic surgical scenarios.
• Further long-term biomechanical data is warranted to fully establish transfacet PSF's role.