Biomechanical comparison of the bone‐screw‐fastener to conventional cortical buttress screw in a simulated ex vivo model of equine midbody proximal sesamoid bone fracture repair

Abstract Objective To compare implant failure and gap displacement characteristics of simulated medial mid‐body proximal sesamoid bone (PSB) fractures repaired with bone‐screw‐fasteners (BSF) or cortical screws (CS) in single or double screw configurations. Study design Ex vivo experimental study. Sample population A total of 14 paired equine cadaver forelimbs. Methods Medial mid‐body PSB osteotomies were created in each forelimb. Surgical repair was performed using either: (1) single 3.5 mm BSF (BSF single ), (2) single 4.5 mm CS (CS single ), (3) two 3.5 mm BSFs (BSF double ), or (4) two 3.5 mm cortical screws (CS double ) ( n = 7 repairs/group). Biomechanical properties and failure characteristics were evaluated through a single cycle to failure. Comparisons between groups were made using Wilcoxon‐matched pairs or Mann–Whitney tests. Statistical significance was p < .05. Results The BSF double group (2081 ± 181 N) had significantly higher yield than BSF single (1458 ± 92 N, p = .01) and CS single (1532 ± 86 N, p = .02) groups. The CS double group (2101 ± 126 N) had significantly higher yield than BSF single ( p = .001) and CS single ( p = .003) groups. Biomechanical properties were not different between BSF single and CS single groups, or between BSF double and CS double groups. Gap measurements at construct failure were significantly higher abaxially than axially in all groups (all p < .05). Conclusion No differences were detected between the single BSF and 4.5 mm CS for repair of medial mid‐body PSB fractures. Surgical repair using two screws has biomechanical advantage to single screw repair, regardless of screw type ex vivo. Clinical significance The BSF is not different to CS for repair of PSB fractures. Counteracting abaxial forces in surgical repair of mid‐body PSB fractures warrants further investigation.