Comparison of a 3-hole 4.5-mm Dynamic Compression Plate and a 7-hole 5.5-mm Y Locking Compression Plate for Arthrodesis of the Proximal Interphalangeal Joint in Horses-an Ex Vivo Biomechanical Study.

The research compares the performance and failure types between a 3-hole 4.5-mm dynamic compression plate and 7-hole 5.5-mm Y locking compression plate during single cycle axial loading tests in the process of arthrodesis (joint fusion) of the Proximal Interphalangeal Joint (PIJ) in horses. The study showed both plates didn’t significantly differ in resistance to axial loading under test conditions with the Y-LCP having a less impact on the palmar/plantar bone, suggesting it may be a safer option.

Experimental Design

• The study aimed to test two types of plates, specifically a 3-hole 4.5-mm dynamic compression plate (DCP) and a 7-hole 5.5-mm Y locking compression plate (Y-LCP), through a single cycle axial loading test in the arthrodesis of the Proximal Interphalangeal Joint (PIJ) in horses.
• Each limb pair was subjected to one of the two plate types for the arthrodesis. The DCP was combined with two transarticular 5.5-mm cortical screws while the Y-LCP was used in conjunction with one transarticular 4.5-mm cortical screw. Cortical screws were inserted in lag fashion.

Testing and Results

• The constructs were submitted to failure by applying a single axial load cycle. This simulates the stresses the joint and construct would experience in a real-world setting.
• The stiffness, load, and deformation resulting from this applied load were analyzed for each construct type.
• Both the DCP and Y-LCP constructs showed no significant differences in their resistance to axial loading. The stiffness of the DCP and Y-LCP constructs were roughly the same, 5685.22 N/mm and 6591.10 N/mm, respectively.

Conclusions

• The study found that using DCP or Y-LCP for PIJ arthrodesis in horses results in biomechanically equivalent outcomes. That is, both constructs withstand the same amount of load before failure, and they deform in roughly the same manner.
• However, the use of the Y-LCP plate impacts the palmar/plantar bone less, which can be of importance as less impact can reduce the risk of additional injury or trauma.
• Therefore, the study suggests that Y-LCP with unicortical screws could provide a safer alternative for PIJ arthrodesis, as it avoids potential trauma caused by utilizing bicortical screws in the palmar/plantar region of the pastern.