Mechanical Properties and Failure Mode of Proximal Screw Fixation Technique Using Locking Compression Plate for Proximal Interphalangeal Arthrodesis in Horses: An Ex Vivo Study.

This study investigates the mechanical properties and failure modes of different methods of proximal screw fixation with a locking compression plate for pastern joint arthrodesis in equine cadavers. The results show that the type of screw and its anchoring method do not impact the mechanical properties of the arthrodesis.

Study Design and Methodology

• The study was conducted on 20 forelimbs of equine cadavers.
• The pastern joint arthrodesis was performed with a 3-hole 4.5-mm narrow locking compression plate.
• The specimens were randomized into four groups based on the method of fixation and type of proximal screw used: unicortical cortex, bicortical cortex, unicortical locking, bicortical locking.
• Each specimen underwent a single-cycle axial compression test until failure. The deformation of the implant was also recorded.
• Post-failure analysis was performed using computed tomography scans and fractal analysis to study bone failure.

Results and Findings

• No significant differences were found in the mechanical properties and fractal dimensions among the four groups.
• Regardless of the group, transarticular screws showed a higher frequency of deformation (75%).
• Plate deformation was more frequently observed in both unicortical locking and bicortical locking groups.

Conclusions

• The type of screw used in the proximal hole of the locking compression plate and its method of anchoring in the proximal phalanx do not influence the mechanical properties of pastern arthrodesis in equine cadavers.
• The results were obtained from single-cycle axial compression tests until failure.