Biomechanical comparison between various screw fixation angles for Latarjet procedure: a cadaveric biomechanical...

Area of Science:

• Orthopedic surgery
• Biomechanics
• Anatomical studies

Background:

• The Latarjet procedure effectively treats anterior glenohumeral instability with bone loss.
• Biomechanical properties of screw fixation angles (α angle) in Latarjet procedures are not well-understood.

Purpose of the Study:

• To compare fixation stability, failure load, and failure mechanisms across different α angles in Latarjet procedures using cadaver specimens.

Main Methods:

• Twenty-four cadaver shoulder specimens with a 25% glenoid defect were used.
• Coracoid process grafts were fixed with screws at α angles of 0°, 15°, and 30°.
• Cyclic loading and ultimate failure testing were performed to measure displacement and failure modes.

Main Results:

• No significant difference in gross displacement was observed between groups under cyclic loading.
• Increased interface displacement occurred at a 30° α angle compared to 0° at 150-N load.
• All specimens failed by screw cutout, with similar ultimate failure loads across all groups.

Conclusions:

• Increasing the α angle to 30° significantly increases displacement after cyclic loading in Latarjet procedures.
• Screws should be placed nearly parallel to the glenoid surface.
• α angles exceeding 30° should be avoided to maintain fixation stability.