In vitro biomechanical evaluation and comparison of a new prototype locking plate and a limited-contact self compression plate for equine fracture repair.

The researchers evaluated and compared the mechanical strength and stiffness of a new type of broad locking plate with that of a traditional self-compression plate for equine fracture repair. They found the new prototype locking plate to be comparable to the traditional plate in its properties, with similar performance under bending and torsional forces.

Objective of the Research

• The aim of the study was to test whether a new 4.5mm broad prototype locking plate (NP-LP) had mechanical properties similar to a traditional 4.5mm broad limited-contact self-compression plate (LC-SCP).
• The bending and torsional properties of both types of plates were also compared when applied to osteotomized equine third metacarpal bones (MC3) with a simulated fracture.

Methodology

• The research team tested the plates independently in a four-point bending single cycle to failure.
• Then, constructs of each plate type with osteotomized MC3 bones were created, with a 1 cm gap at the fracture site.
• These constructs were tested in three ways: four-point bending single cycle to failure, four-point bending cyclic fatigue, and torsion single cycle to failure.

Results

• There was not a significant difference in the bending strength and stiffness between the two types of fixation plates.
• However, when inserted into the MC3 bones, the construct using the NP-LP was significantly stiffer in bending than the construct with the LC-SCP.
• There were no other significant differences between the two platforms in terms of bending, yield load in torsion, or composite rigidity.
• Both constructs lasted for a similar number of cycles to failure in bending fatigue testing.

Conclusions

• The new prototype locking plate was found to be mechanically comparable to the LC-SCP, with both intrinsic and structural properties equivalent.
• The NP-LP provided more rigidity than the LC-SCP under four-point bending but performed similarly in four-point bending fatigue testing and torsion single cycle failure.
• The researchers concluded that the new fixation implant is a viable alternative to the traditional model for equine fracture repair, at least in a simulated MC3 fracture scenario.