In vitro biomechanical comparison of locking compression plate fixation and limited-contact dynamic compression plate fixation of osteotomized equine third metacarpal bones.

The research compares the effectiveness of two types of plates used to repair horse bone fractures. The results indicate that the locking compression plate was superior in resisting overload forces and fatigue.

Research Objective

• The research aimed to compare the biomechanical properties and fatigue life of two types of plates used in the repair of equine bone fractures: the broad-locking compression plate (LCP) and the limited contact dynamic compression plate (LC-DCP). The objective was to determine which of the two provides a more effective fixation of osteotomized equine third metacarpal (MC3) bones.

Research Methodology

• The researchers conducted in-vitro biomechanical testing on paired cadaveric adult equine MC3 bones. The bones were divided into three groups for different kinds of testing: 4-point bending single cycle to failure testing, 4-point bending cyclic fatigue testing, and torsional single cycle to failure testing.
• An 8-hole, 4.5 mm LCP and an 8-hole, 4.5 mm LC-DCP were each applied to a selected bone from each pair. The fixation techniques followed standard ASIF techniques, and each bone was subject to mid-diaphyseal osteotomies before the application of the plates.
• The findings were statistically analyzed within each group using a paired t-test. The researchers set the significance level at P<0.05.

Research Findings

• The research found that LCP fixation offered significantly greater yield load, yield bending moment, composite rigidity, failure load and failure bending moment under 4-point bending, single cycle to failure, than the LC-DCP fixation.
• Similarly, under 4-point bending cyclic fatigue testing, the LCP fixation also showed superior mean cycles to failure compared to the LC-DCP fixation.
• Moreover, the LCP fixation exhibited significantly greater yield load, composite rigidity, and failure load under torsional single cycle to failure testing than the LC-DCP fixation.

Research Conclusions and Implications

• Based on these in-vitro findings, the research concluded that the 4.5 mm LCP was superior to the 4.5 mm LC-DCP in terms of resisting static overload forces, such as palmarodorsal 4-point bending and torsion, as well as in resisting cyclic fatigue under palmarodorsal 4-point bending.
• These findings might aid in choosing the appropriate plate for the repair of equine long bone fractures, potentially pointing to the preference of the LCP in such procedures.