Long Bone Fracture Reduction and Deformity Correction Using the Hexapod External Fixator With a New Method: a Feasible Study and Preliminary Results

Abstract Background: The hexapod external fixator (HEF), such as the Taylor spatial frame (TSF), offering the ability of simultaneous correction of the multidirectional deformities without frame modification, whereas there are so many parameters for surgeons to measure and subjective errors will occur inevitably. The purpose of this study was to evaluate the effectiveness of a new method based on computer-assisted three-dimensional (3D) reconstruction and hexapod external fixator for long bone fracture reduction and deformity correction without calculating the parameters needed by the computer program.Methods: This retrospective study consists of 25 patients with high-energy tibial diaphyseal fractures treated by the HEF at our institution from January 2016 to June 2018, including 22 males and 3 females with a mean age of 42 years (range 14-63 years). Hexapod external fixator treatments were performed due to primary and definitive management of multiplanar posttraumatic deformity and/or severe soft-tissue damage that were not suitable for internal fixation in the tibia. Computer-assisted 3D reconstruction and trajectory planning of the reduction by Mimics were applied to perform virtual fracture reduction and deformity correction. The electronic prescription derived from the length changes of the six struts were calculated by SolidWorks. Fracture reduction was conducted by adjusting the lengths of the six struts according to the electronic prescription. The standard anteroposterior (AP) and lateral X-rays after reduction were taken to evaluate the effectiveness.Results: All patients acquired excellent functional reduction (most cases achieved anatomical reduction) in our study. The mean coronal plane translation (1.0±1.1 mm), coronal plane angulation (0.8±1.2°), sagittal plane translation (0.8±1.0 mm) and sagittal plane angulation (0.3±0.8°) after correction were all less than those (6.1±4.9 mm, 5.2±3.2°, 4.2±3.5 mm, 4.0±2.5°) before correction (P<0.05).Conclusion: The computer-assisted three-dimensional reconstruction and hexapod external fixator-based method allows surgeons to conduct long bone fracture reduction and deformity correction without calculating the parameters needed by the computer program. Considering the radiologic exposure, this method is suggested to apply in those unusually complex cases with extensive soft tissue damage and internal fixation is impossible or inadvisable.