Biomechanical comparison of double mini-locking plate versus lateral locking plate for Danis-Weber B distal fibula fractures

Lateral locking plate (LLP) is a successful standard treatment for Danis-Weber B distal fibula fractures. However, its uniplanar nature can be a limitation when insufficient bone is available at the distal fragment for secure screw fixation, particularly in low or osteoporotic fractures. This study evaluated the biomechanical performance of a novel biplanar double mini-locking plate (DMLP) system designed to address this challenge. Twenty left fibula Sawbones models were used to simulate Danis-Weber B fractures. The samples were divided into two groups, Group A (DMLP) and Group B (LLP), with 10 samples in each group. Biomechanical testing included quasistatic axial compression, torsional loading, and torsional failure tests to assess the stiffness, displacement, failure mode, and failure torque. Biomechanical testing revealed that Group A exhibited superior structural properties compared with Group B. In the axial compression test, the compression stiffness of Group A was 31% greater than that of Group B (402.8 ± 100.4 N/mm vs. 308.4 ± 60.51 N/mm, p = 0.0202). In the torsion tests, Group A demonstrated significantly greater torsional stiffness within the 0.25–0.5 N·m range (0.42 ± 0.05 N·m/° vs. 0.29 ± 0.17 N·m/°, p = 0.0172) and the 0.5–1.0 N·m range (0.39 ± 0.03 N·m/° vs. 0.27 ± 0.16 N·m/°, p = 0.0191). Additionally, the failure torque in Group A was approximately 26% greater (14.21 ± 2.01 N·m vs. 11.24 ± 1.47 N·m, p = 0.0036). Digital image correlation (DIC) analysis revealed that Group A had significantly reduced relative displacement at the fracture site under axial compression (-0.12 ± 0.06 mm vs. -0.32 ± 0.15 mm, p = 0.0011) and at 10° of torsion (0.68 ± 0.14 mm vs. 1.23 ± 0.21 mm, p < 0.0001). All fractures occurred at the proximal end, with no significant difference in failure location between the two groups ( p = 1.000). In this in vitro biomechanical study using Sawbones models, the DMLP demonstrated superior performance compared to the LLP for the fixation of simulated Danis-Weber B distal fibula fractures. Under the quasistatic loading conditions tested, the DMLP construct exhibited significantly greater axial stiffness, torsional stability, and failure torque. These findings provide a strong biomechanical rationale, based on this standardized experimental model, warranting further investigation for its potential clinical application. Not applicable.