Biomechanical comparison of three internal fixation configurations for low transcondylar fractures of the distal humerus. Issue 2 (February 2023)

• Record Type: Journal Article
• Authors: Zha, Yejun; Hua, Kehan; Huan, Yong; Chen, Chen; Sun, Weitong; Ji, Shangwei; Xiao, Dan; Gong, Maoqi; Jiang, Xieyuan
• Is Part Of: Injury. Volume 54:Issue 2(2023)
• Page Start: 362
• Page End: 369
• Publication Date: 2023-02
• Subjects: Low transcondylar fracture -- Distal humerus -- Biomechanical study -- Internal fixation; Wounds and injuries -- Surgery -- Periodicals; Accidents -- Periodicals; Wounds and Injuries -- surgery -- Periodicals; Lésions et blessures -- Chirurgie -- Périodiques; Electronic journals; Electronic journals; 617.1
• DOI: 10.1016/j.injury.2022.10.025
• Languages: English
• ISSNs: 0020-1383

Abstract

Highlights: Few previous studies concerning biomechanical properties of different internal fixation for low transcondylar fractures of the distal humerus. Traditional orthogonal and parallel double-plate configurations, and PPMS construct (posterolateral plate + medial screw) were compared. Axial loading, posterior bending, internal torsion for construct stiffness and failure test under axial loading for construct strength were tested. Combining all results, the overall stiffness and strength of parallel configuration were superior to orthogonal and PPMS configurations. PPMS configuration can provide adequate stability and stiffness comparable double-plate methods under axial loading. Abstract: Background: We aimed to evaluate the biomechanical stiffness and strength of different internal fixation configurations and find suitable treatment strategies for low transcondylar fractures of the distal humerus. Methods and materials: Thirty 4 th generation composite humeri were used to create low transcondylar fracture models that were fixed by orthogonal and parallel double plates as well as posterolateral plate and medial screw (PPMS) configurations (n=10 in each group) using an anatomical locking compression plate-screw system and fully threaded medial cortical screws. Posterior bending (maximum 50 N), axial loading (maximum 200 N) and internal rotation (maximum 10 N·m) were tested, in that order, for each specimen. Stiffness under different biomechanical settings among different configurations were compared. Another 18 sets of fracture models were created using these three configurations (n=6 in each group) and the load to failure under axial loading among different configurations was compared. Results: Under posterior bending, the stiffness of parallel group was higher than orthogonal group (P<0.001), and orthogonal group was higher than PPMS group (P<0.001). Under axial loading, the stiffness of parallel group was higher than orthogonal group (P=0.001) and PPMS group (P<0.001); however, the difference between orthogonal and PPMS group was not statistically significant (P>0.05). Under internal rotation, the stiffness of parallel group was higher than orthogonal group (P=0.044), and orthogonal group was higher than PPMS group (P=0.029). In failure test under axial loading, the load to failure in the orthogonal group was lower than parallel group (P=0.009) and PPMS group (P=0.021), but the difference between parallel group and PPMS group was not statistically significant (P>0.05). All specimens in orthogonal group demonstrated "distal medial failure"; most specimens had "distal medial and trochlear failure" in the parallel group; most specimens exhibited "contact failure" in the PPMS group. Conclusion: For treating low transcondylar fractures, the overall stiffness and strength of the parallel configuration were superior to those of the orthogonal and PPMS configurations. Nevertheless, the PPMS configuration can provide adequate stability and stiffness comparable to double-plate configurations under axial loading. Therefore, the PPMS construct may have certain clinical value.