The Effect of Variable-Pitch Headless Compression Screws and Cortical Screws on Interfragmentary Compression: An In...

Area of Science:

• Veterinary Orthopaedics
• Biomechanical Engineering
• Surgical Implant Design

Background:

• Articular fractures require precise reduction and rigid fixation for optimal healing.
• Cortical lag screws (CLSs) are standard for lateral humeral condyle fractures in veterinary medicine, but have high complication rates.
• Variable-pitch headless compression screws (VPHCSs), common in human orthopaedics, are underutilized in veterinary applications.

Purpose of the Study:

• To compare the biomechanical performance of VPHCSs against CLSs in a simulated transverse fracture model.
• Specifically, to evaluate peak interfragmentary force (PIF) and area of compression (AOC) generated by each screw type at varying insertion depths.

Main Methods:

• A polyurethane foam model simulated a transverse fracture.
• 3.5 mm CLSs and 3.5 mm VPHCSs were tested.
• Pressure-sensitive film measured PIF and AOC between foam blocks.
• VPHCSs were inserted to depths of 2, 5, and 9 mm below the surface, while CLSs were inserted in lag fashion.

Main Results:

• No significant difference in PIF and AOC was found between CLSs and VPHCSs inserted to 2 mm depth.
• VPHCSs inserted to 5 mm and 9 mm depths generated significantly greater PIF compared to CLSs.
• Deeper VPHCS insertion (5 mm and 9 mm) resulted in significantly greater AOC than CLSs.

Conclusions:

• VPHCSs, particularly when inserted deeper, offer superior compression compared to CLSs in this simulated fracture model.
• These findings suggest VPHCSs may be a viable alternative for veterinary fracture fixation.
• Further research is needed to guide clinical application of VPHCSs in veterinary orthopaedics.