In vitro comparison of a novel external fixator and traditional full-limb transfixation pin cast in horses.

This study compares the mechanical properties and failure rates of three methods used to stabilize bone fractures in horses: transfixation pin cast (TPC), modular-sidebar external skeletal fixator (ESF), and solid-sidebar ESF. The researchers find that the solid-ESF is the most resilient and reliable method under static or cyclic axial loading to failure.

Research Methodology

• The research was conducted as an in vitro study using equine cadaver forelimbs.
• A 30 degrees oblique distal radial osteotomy (a surgical operation to correct bone deformities) was created in each forelimb.
• Each osteotomy was stabilized using one of the three fixation methods: TPC, modular-ESF, or solid-ESF.
• Both static (applied to all three methods) or cyclic (applied to TPC and solid-ESF only) axial loading to failure was performed on the limbs. Axial loading refers to the application of force along the axis of an object.
• Various mechanical properties were measured, including stiffness, yield load, yield displacement, failure load, and failure displacement for static loading. For cyclic loading, the number of cycles to failure at 75% failure load were obtained.
• The data collected was analyzed using a statistical tool known as the Kruskal-Wallis test with a level of significance set at P<.05.

Results and Conclusion

• The results demonstrated that the solid-ESF method was superior to both TPC and the modular-ESF in terms of stiffness, yield and failure load, and lower yield and failure displacement.
• TPC showed better results compared to the modular-ESF method in aspects like higher yield load, failure load, and yield displacement.
• When comparing the number of cycles to failure, the solid-ESF method outperformed TPC. The solid-ESF lasted for an average of 6560+/-90 cycles under a load of 25,000 N, while the TPC lasted for an average of 2996+/-657 cycles under a load of 16,000 N.
• On the basis of these results, the study suggests that solid-ESF, being stiffer and stronger and capable of withstanding a greater number of cycles in axial loading, could be a viable alternative to the traditional TPC for stabilizing long bone fractures in adult horses.
• The researchers however note that this study is just an initial step in evaluating the solidity of the solid-ESF method, calling for further testing to firmly establish its validity.