title: Biomechanical evaluation of two commonly used external fixators in the treatment of open subtalar dislocation--a finite element analysis.
abstract: Subtalar dislocation is a rare injury caused by high-energy trauma. Current treatment strategies include leg casts, internal fixation and external fixation. Among these, external fixators are the most commonly used as this method is believed to provide better stabilization. However, the biomechanical stability provided by these fixators has not been demonstrated. This biomechanical study compares two commonly used external fixators, i.e. Mitkovic and Delta. CT imaging data were used to reconstruct three-dimensional models of the tibia, fibula, talus, calcaneus, navicular, cuboid, three cuneiforms and five metatarsal bones. The 3D models of the bones and cartilages were then converted into four-noded linear tetrahedral elements, whilst the ligaments were modelled with linear spring elements. Bones and cartilage were idealized as homogeneous, isotropic and linear. To simulate loading during walking, axial loading (70 N during the swing and 350 N during the stance phase) was applied at the end of diaphyseal tibia. The results demonstrate that the Mitkovic fixator produced greater displacement (peak 3.0mm and 15.6mm) compared to the Delta fixator (peak 0.8mm and 3.9 mm), in both the swing and stance phase, respectively. This study demonstrates that the Delta external fixator provides superior stability over the Mitkovic fixator. The Delta fixator may be more effective in treating subtalar dislocation.
authors.affiliation: Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia. Electronic address: mhanif008@gmail.com.
authors.forename: Muhammad Hanif
authors.initials: MH
authors.lastname: Ramlee
authors.affiliation: Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia. Electronic address: rafiq@biomedical.utm.my.
authors.forename: Mohammed Rafiq Abdul
authors.initials: MR
authors.lastname: Kadir
authors.affiliation: Tissue Engineering Group (TEG), National Orthopaedic Centre of Excellence in Research and Learning (NOCERAL), Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur, Malaysia. Electronic address: mrmurali08@gmail.com.
authors.forename: Malliga Raman
authors.initials: MR
authors.lastname: Murali
authors.affiliation: Tissue Engineering Group (TEG), National Orthopaedic Centre of Excellence in Research and Learning (NOCERAL), Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur, Malaysia. Electronic address: tkzrea@um.edu.my.
authors.forename: Tunku
authors.initials: T
authors.lastname: Kamarul
mesh_terms: D001696:Biomechanical Phenomena; D016267:External Fixators; D020342:Finite Element Analysis; D033023:Foot Joints / Q000000981:diagnostic imaging / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D055595:Mechanical Phenomena; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing
keywords: Biomechanics; External fixator; Finite element analysis; Stability; Subtalar dislocation