Biomechanical properties of bicortical and monocortical plate fixation for rib fractures in the adolescent human rib fracture model

Purpose: The technical advancement of surgical stabilization of ribs often prevents the surgeons from fixation, despite the procedures documented improved outcomes. The aim of this study was to evaluate a less invasive approach involving a simplified monocortical rib fixation technique. Methods: Eighteen frozen human ribs obtained intraoperatively from young individuals aged 13-18 were employed for this study. First, the ribs were fractured under three-point bending, with their intrathoracic side put under tensile stress. Following this, the ChM 4.0 rib fixation system was utilized. The specimens were categorized into two groups: bicortical fixation (n = 9) and monocortical fixation (n = 9). Subsequently, bicortical and monocortical fixation groups underwent dynamic testing over 400 000 cycles under combined sinusoidal tensile bending and torsional loading (2-5 N at 3 Hz). In the final stage, all samples were subjected to a destructive load to failure. Results: Our analysis revealed that the fixation method did not demonstrate statistically significant differences in terms of preliminary bending stiffness ( p = 0.379). Similarly, undergoing a course of 400 000 cycles involving combined tensile and torsional loading did not constitute a statistically significant factor affecting the monocortical and the bicortical fixation groups ( p = 0.894). In the monocortical fixation group, all specimens failed due to screws pulled out from the bone. In contrast, all specimens in the bicortical fixation group exhibited failure attributed to fractures occurring just behind the plate. Nonetheless, the fixation method was not a significant factor affecting bending strength ( p = 0.863). Conclusions: The monocortial fixation could be a reasonable option among younger populations with comparable stability of fixation.