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Pull-out strength of the suprapedicle claw construct: a biomechanical study
Abdulrazzaq Alobaid1, Vincent Arlet, Andre Busato
1McGill University Spine Center, Montreal, Canada.
Summary
A novel suprapedicular hook construct significantly enhances anterior vertebral body screw fixation strength by 80% in scoliosis surgery. This claw configuration improves pull-out resistance, offering a safer and more robust spinal instrumentation solution.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Spinal Instrumentation
Background:
- Superior screw pull-out is a recognized complication in anterior spine instrumentation for scoliosis.
- Existing fixation methods require biomechanical evaluation for improved pull-out strength.
Purpose of the Study:
- To compare the pull-out strength of three anterior vertebral body fixation constructs.
- To evaluate a novel suprapedicular hook (claw) construct against standard methods.
Main Methods:
- Biomechanical pull-out study using cadaveric thoracic spine specimens (T4-T9).
- Three fixation constructs were tested: bicortical screw alone, screw with washer, and screw with suprapedicular hook (claw).
- Screw extraction was performed using a material testing system after measuring bone mineral density.
Main Results:
- The claw construct demonstrated significantly higher ultimate fixation strength (1244 N) compared to the screw alone (631 N) and screw with washer (711 N) (P<0.0001).
- The claw construct improved pull-out strength by approximately 80%.
- Low bone mineral density reduced the benefit of the claw construct.
Conclusions:
- The suprapedicular claw construct substantially enhances anterior vertebral body screw pull-out strength.
- This novel construct offers improved fixation stability and potentially reduces the risk of screw pull-out in scoliosis surgery.
- The claw configuration alters failure modes, enhancing overall construct integrity.