Biomechanical properties testing of Maharat Nakhon Ratchasima hospital external fixator system, comparison between the old and new joint designs

Abstract

Objectives: To test the biomechanical properties of the old and new joints of Maharat Nakhon Ratchasima hospital external fixator Methods: This experimental study used 18 pieces of the right side legs of the pig approximately equal in size, length, width, configuration, without the broken bone. The specimens were randomly allocated into 2 equal groups. All specimens were fixed with the external fixator with the new joint for the first and the old joint designs for the second groups with the control of the point of bone drilling, the perpendicular direction of screw insertion, the depth of screw insertion, the height of the metal rod from the anterior cortex of the bone, the maximal tight of each part of the external fixator, and the point and perpendicular direction of bone cutting at the middle part of pig’s tibial bone. All specimens were tested and recorded against the forces in compression, bending and torsion directions. Results: In compression and torsion mode, the new joint design tolerated forces lesser than the old one. In bending mode, the new joint design tolerated forces more than the old one. There were no statistically significant differences between the old and new joint designs in any mode of force. Conclusion: The old and new joint designs of external fixator system had no statistically significant difference in the biomechanical properties.