title: Influence of fracture geometry on bone healing under locking plate fixations: A comparison between oblique and transverse tibial fractures.
abstract: Mechano-regulation plays a crucial role in bone healing and involves complex cellular events. In this study, we investigate the change of mechanical microenvironment of stem cells within early fracture callus as a result of the change of fracture obliquity, gap size and fixation configuration using mechanical testing in conjunction with computational modelling. The research outcomes show that angle of obliquity (θ) has significant effects on interfragmentary movement (IFM) which influences mechanical microenvironment of the callus cells. Axial IFM at near cortex of fracture decreases with θ, while shear IFM significantly increases with θ. While a large θ can increase shear IFM by four-fold compared to transverse fracture, it also result in the tension-stress effect at near cortex of fracture callus. In addition, mechanical stimuli for cell differentiation within the callus are found to be strongly negatively correlated to angle of obliquity and gap size. It is also shown that a relatively flexible fixation could enhance callus formation in presence of a large gap but could lead to excessive callus strain and interstitial fluid flow when a small transverse fracture gap is present. In conclusion, there appears to be an optimal fixation configuration for a given angle of obliquity and gap size.
authors.affiliation: Department of Infrastructure Engineering, The University of Melbourne, Victoria 3010, Australia. Electronic address: s.miramini@unimelb.edu.au.
authors.forename: Saeed
authors.initials: S
authors.lastname: Miramini
authors.affiliation: Department of Infrastructure Engineering, The University of Melbourne, Victoria 3010, Australia. Electronic address: lihzhang@unimelb.edu.au.
authors.forename: Lihai
authors.initials: L
authors.lastname: Zhang
authors.affiliation: The Epworth Richmond Hospital, Victoria 3121, Australia. Electronic address: orthovic@gmail.com.
authors.forename: Martin
authors.initials: M
authors.lastname: Richardson
authors.affiliation: Department of Infrastructure Engineering, The University of Melbourne, Victoria 3010, Australia. Electronic address: pamendis@unimelb.edu.au.
authors.forename: Priyan
authors.initials: P
authors.lastname: Mendis
authors.affiliation: Department of Medicine, School of Clinical Sciences, Monash University, Monash Medical Centre, Victoria 3168, Australia. Electronic address: peter.ebeling@monash.edu.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ebeling
mesh_terms: D001860:Bone Plates; D017102:Fracture Healing; D006801:Humans; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D014057:Tomography, X-Ray Computed
keywords: Bone fracture healing; Cell differentiation; Computational modelling; Interfragmentary movement; Mechanical testing; Oblique fracture