There is direct relationship between bone bridge length and coracoclavicular fixation resistance to failure: Biomechanical study in a porcine model

Abstract

Background: This study aims to evaluate the relation between coracoclavicular resistance to failure and the distance between clavicular tunnels. The hypothesis is that a greater clavicular bone bridge between tunnels achieves a stronger coracoclavicular fixation. Methods: Descriptive Laboratory Study. Thirty-six (36) coracoclavicular models were constructed utilizing porcine metatarsals. Coracoclavicular stabilizations were performed using a subcoracoid loop fixation configuration through two clavicular tunnels, tied at the clavicle's superior cortex using a locking knot. Models were randomly assigned to 1 of 3 experimental groups of variable bone bridge length between clavicular tunnels: 5 mm, 10 mm, and 15 mm. Each group had 12 models. Fixation resistance was assessed through the ultimate failure point under an axial load to failure trial. Failure patterns were documented. A one-way ANOVA test was used, and a Tukey post hoc as needed (P < 0.05). Findings: Mean strength per bone bridge length: 5 mm = 312 N (Range: 182-442 N); 10 mm = 430 N (Range: 368-595 N); 15 mm = 595 N (Range: 441-978 N). The 15 mm group had a significantly higher ultimate failure point than the other two groups: 5 mm (P < 0.001) and 10 mm (P < 0.001). All fixations systematically failed by a superior cortex clavicle fracture at the midpoint between tunnels. Interpretation: A direct relationship between bone bridge length and coracoclavicular resistance to failure was demonstrated, being the 15 mm length a significantly higher strength construct in a tied loop model.