In vitro comparison of linear vs triangular screw configuration to stabilize complete uniarticular parasagittal fractures of the proximal phalanx in horses.

This study examines the effectiveness of linear and triangular screw configurations in repairing fractures of the proximal phalanx (a bone in the forelimb of horses). The results suggest that triangular screw configurations provide greater stability and reduced gaps in fractures, potentially improving postoperative conditions for the animals.

Methodology

• The researchers utilized 14 equine cadaver limbs for the study. These simulated fractures were fixed with two lag screws under a specific level of insertion torque, forming a linear repair.
• CT imaging was performed on the repaired legs both unloaded and loaded to replicate the forces that would come into play while walking.
• The initial linear repair was modified to a triangular repair, using three lag screws, followed by similar CT imaging as above.
• Two independent observers assessed the resultant fracture gap qualitatively, grading it based on gap measurements at dorsal, mid, and palmar P1 sites relative to the average voxel size.
• The researchers used Cohen’s κ to evaluate the interobserver agreement and Kendall’s τ-b correlation coefficients and paired nonparametric tests to judge the impact of repair type, loading condition, and measurement site on the fracture gap grades. In all cases, statistical significance was considered if P was less than or equal to 0.05.

Results

• The researchers found a fair agreement for fracture gap widening in the triangular repair setup (κ = 0.53), while the linear repairs demonstrated excellent agreement (κ = 0.81).
• Loading led to an increase in fracture gap distractions in the linear repair model (Plinear = 0.008).
• Triangular repairs proved superior at reducing fracture gaps, regardless of loading (Punloaded = 0.003; Ploaded < 0.001).
• The repair type didn’t have any correlation with the fracture gap grades at the unloaded mid and loaded dorsal P1 sites.

Conclusions

• The study concludes that triangular screw configurations for repair of complete, uniarticular, parasagittal fractures in a horse’s proximal phalanx bone result in better in-vitro fracture gap reduction and stability.
• The researchers suggest that the use of a triangular lag screw configuration could lead to improved biomechanical conditions during the postoperative weight-bearing phase.