Effect of Arthrodesis Device Type and Trajectory on Subtalar Joint Compression

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Biomaterials science

Background:

• Subtalar arthrodesis is used for hindfoot issues, but fusion failures occur in at-risk patients.
• Current methods use cannulated screws, but sustained dynamic compression devices show promise.

Purpose of the Study:

• To compare static and dynamic compression devices for subtalar joint compression.
• To evaluate the effect of device trajectory on joint compression.

Main Methods:

• A custom mechanical testing fixture was used.
• Compression was measured for a dynamic device (anterior/posterior trajectories) versus two static screws (parallel/diverging trajectories).

Main Results:

• Dynamic compression devices yielded 53% greater compression than static devices.
• Device trajectory did not impact joint compression forces for either type.

Conclusions:

• A single dynamic compression device provides superior and consistent joint compression over two static screws.
• Dynamic compression devices show potential for improving subtalar fusion in at-risk or revision cases.