In vitro biomechanical properties of 2 compression fixation methods for midbody proximal sesamoid bone fractures in horses.

The study analyzes two methods to repair a common type of bone fracture in horses’ limbs, comparing their ability to withstand force and their influence on surrounding soft tissue. Both techniques emerge as adequately strong and able to handle normal walking strain post-surgery.

Experiment Background

• This research tested two different techniques for repairing fractures in the sesamoid bone, a bone in the horse’s forelimb, to see which solution is most effective.
• The two methods of repair were a screw-based fix and a wire-based fix.
• The strength of these repairs under strain and their associated soft-tissue strain during focused pressure (monotonic loading) were measured.

Methodology

• Paired horse forelimbs from ten race-trained horses were used in the trial.
• A planned fracture was created in the sesamoid bone, and each break was repaired with either a screw or a wire.
• Strain was measured by placing differential variable reluctance transducers in the suspensory apparatus and distal sesamoidean ligaments.
• The limbs were put under axial compression in a single cycle until failure, in order to understand how much force each repair method could tolerate.

Results

• The screw repairs withstood an average force of 2,908.2 N, with one limb not failing even when subjected to 5,000 N.
• All the wire repairs failed at an average of 3,406.3 N.
• Statistical analysis found no significant difference in the average yield load that the two repair methods could endure.
• There was also no significant difference in the maximum strain caused in the soft tissues attached to the sesamoid bones by the two repair methods.

Conclusions

• All methods of repaired limbs withstood loads equivalent to what would be experienced in vivo during a horse’s walk.
• Both techniques showed adequate yield strength for immediate post-operative repair of fractures in the horse’s sesamoid bone.