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A comparative mechanical study of 3 external fixator clamps.
R S Gilley1, C A Bourgeault, L J Wallace
1Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA.
Veterinary Surgery : VS
|July 10, 2001
Summary
The Kirschner-Ehmer (K-E) clamp resisted higher axial and torsional forces than Meynard or Synthes clamps. Clamp-fixator pin interface offered the weakest torsional resistance, impacting fracture reduction stability.
Area of Science:
- Orthopedic biomechanics
- Biomaterials science
- Surgical device engineering
Background:
- External fixator clamps are crucial for fracture reduction stability.
- Understanding clamp mechanical properties is essential for effective rigid fixation.
- Comparative data on different clamp types is limited.
Purpose of the Study:
- To compare the mechanical properties of Kirschner-Ehmer (K-E), Synthes, and Meynard external fixator clamps.
- To evaluate clamp performance under varying torque loads across six mechanical parameters.
- To identify the weakest mechanical parameters influencing clamp stability.
Main Methods:
- Bench testing of six clamps from each of the three manufacturers (K-E, Synthes, Meynard).
- Mechanical testing at applied clamp bolt-tightening torques of 2.5, 5.0, and 7.5 Newton-Meters.
- Assessment of axial and torsional slippage, and pivot resistance.
Main Results:
- K-E clamps exhibited axial and torsional slippage at higher forces, except for clamp bolt axis pivot.
- Synthes clamps showed no bolt axis pivot, instead deforming plastically at the fixator-pin interface at higher torques.
- Meynard clamps demonstrated greater torsional resistance than K-E clamps in the clockwise direction, while K-E clamps had higher counterclockwise pivot forces.
Conclusions:
- The K-E clamp demonstrated superior resistance to axial and torsional forces compared to Meynard and Synthes clamps.
- The Synthes clamp exhibited the best torsional resistance around the clamp bolt axis.
- Torsional resistance at the clamp-fixator pin and clamp-connecting bar interface was identified as the most significant weak point in clamp mechanics.