Comparison of 3.5- and 4.0-mm Cortical Bone Screws for Stabilization of an Equine Navicular Bone Fracture Model.

The research article investigates the efficiency of 3.5-mm and 4.0-mm cortical bone screws in stabilizing equine navicular bone fractures. It found out that the 4.0-mm cortical screw demonstrated greater strength and may be a better alternative.

Objective of the Study

• The primary objective of this study is to compare and evaluate the strength and stability provided by 3.5- and 4.0-mm cortical screw-bone constructs when used to repair fractures in the navicular bone of horses.

Methodology

• The study was conducted in vitro and used a four-point bending apparatus for testing.
• It assessed the ability of the two different sized screws to withstand static and cyclic loading.
• The failure load – the load at which the screw-bone construct fails – was determined for both sizes of cortical screws.

Results

• For static testing, the 4.0-mm cortical screw-bone constructs exhibited significantly higher strength (+16% on average) than their 3.5-mm counterparts.
• However, during cyclic testing (continuous loading and unloading), the average number of cycles to failure for the 4.0-mm screw-bone construct was statistically similar to that of the 3.5-mm constructs, which is attributed to a high level of variability in the dataset.

Conclusion

• The research suggests that a 4.0-mm cortical screw provides biomechanical advantages over a 3.5-mm cortical screw when used to treat navicular bone fractures in horses.
• Despite these findings, the study recommends further clinical studies to ascertain if the 4.0-mm screw can be inserted in vivo without any complications.