Biomechanical study on lateral and posterior plate fixation of lateral malleolus fractures

Abstract

Objective To explore the effect of the lateral and posterior ways of internal fixation on the plate in the ankle joint fracture, and provide biomechanical basis for the clinical treatment. Methods Twenty-four fresh specimens of the ankle joint were acquired from the Anatomy Department of Medical College of Fudan University, they were randomly divided into A1, A2, B1, and B2 groups, 6 in each group. A1 and B1 groups were made into coronal fracture of lateral malleolus. A2 and B2 groups were made into sagittal fracture. Then A1 and A2 groups were fixed in lateral plate; B1 and B2 groups were in posterior plate. The intensity, axial compress stiffness, torsion stiffness, and contact mechanics performance index etc. in distal end of fibula with different fixation were tested. Results The coronal fractures of the lateral malleolus in group B1 were better than those of group A1 in axial compress intensity, shear intensity, axial compress stiffness, torque and torsional stiffness, contact surface, except for contact pressure. There were significant differences (t=2.076, 3.468, 3.212, 2.084, 2.162, 2.365, 2.282, all P values<0.05). The sagittal fractures of the lateral malleolus in group B2 were less than those in group A2 in axial compress intensity, shear intensity, axial compress stiffness, torque and torsional stiffness, contact surface, except for contact pressure. There were significant difference (t=2.342, 2.147, 2.876, 3.616, 3.248, 2.015, 2.146, all P values<0.05). Conclusions In coronal fractures of the lateral malleolus, the posterior plate fixation is higher in strength and rigidity than the lateral plate fixed. In sagittal fractures of the lateral malleolus, the lateral plate fixed is more effective than posterior plate fixation. Key words: Ankle joint; Intra-articular fractures; Fracture fixation; Biomechanics