Comparative Stiffness of an Equine Distal Sesamoid Bone Fracture Model Stabilized with 3.5-mm versus 4.5-mm Cortical Bone Screws in Lag Fashion.

This research investigates the relative strength of equine distal sesamoid bone repairs when using different sized cortical bone screws. It found that a 4.5-mm screw-bone construct demonstrated a 28% increase in stiffness compared to a 3.5-mm screw-bone construct, which suggests the larger screw could reduce the risk of implant failure.

Objective of the Study

• The main goal of the research was to examine the comparative stiffness of an equine distal sesamoid bone fracture after it has been repaired using either a single 3.5-mm or a 4.5-mm cortical bone screw in a lag fashion.

Methodology

• The experiment was conducted using a biomechanical study model, simulating an axial sagittal fracture in the equine distal sesamoid bones.
• Treatments included installing either a 3.5-mm or 4.5-mm cortical screw.

Results

• The research revealed that the stiffness value for the fracture repaired with a 4.5-mm screw-bone structure (522.49 N/mm ± 168.21) was significantly larger than the one repaired using the 3.5-mm screw-bone structure (408.46 N/mm ± 131.13).
• This data suggests that the 4.5-mm screw-bone construct is 28% stiffer, on average, compared to the 3.5-mm construct.

Conclusions

• The study concludes that repair of fractured distal sesamoid bones in horses using a 4.5-mm screw-bone construct leads to stiffer repair by a margin of 28%, compared to using a 3.5-mm screw-bone construct.
• This stiffer repair is believed to be able to withstand more force from anaesthetic recovery, normal weight bearing, and athletic exercise. This, in turn, minimizes the risk of implant failure.