title: The initial phase of fracture healing is specifically sensitive to mechanical conditions.
abstract: Interfragmentary movements affect the quality and quantity of callus formation. The mounting plane of monolateral external fixators may give direction to those movements. Therefore, the aim of this study was to determine the influence of the fixator mounting plane on the process of fracture healing. Identically configured fixators were mounted either medially or anteromedially on the tibiae of sheep. Interfragmentary movements and ground reaction forces were evaluated in vivo during a nine week period. Histomorphological and biomechanical parameters described the bone healing processes. Changing only the mounting plane led to a modification of interfragmentary movements in the initial healing phase. The difference in interfragmentary movements between the groups was only significant during the first post-operative period. However, these initial differences in mechanical conditions influenced callus tissue formation significantly. The group with the anteromedially mounted fixator, initially showing significantly more interfragmentary movements, ended up with a significantly smaller callus diameter and a significantly higher callus stiffness as a result of advanced fracture healing. This demonstrates that the initial phase of healing is sensitive to mechanical conditions and influences the course of healing. Therefore, initial mechanical stability of an osteosynthesis should be considered an important factor in clinical fracture treatment.
authors.affiliation: Trauma and Reconstructive Surgery, Charité, Campus Virchow-Klinikum, Humboldt University of Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Klein
authors.forename: Hanna
authors.initials: H
authors.lastname: Schell
authors.forename: Florian
authors.initials: F
authors.lastname: Streitparth
authors.forename: Markus
authors.initials: M
authors.lastname: Heller
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Kassi
authors.forename: Frank
authors.initials: F
authors.lastname: Kandziora
authors.forename: Hermann
authors.initials: H
authors.lastname: Bragulla
authors.forename: Norbert P
authors.initials: NP
authors.lastname: Haas
authors.forename: Georg N
authors.initials: GN
authors.lastname: Duda
mesh_terms: D000818:Animals; D002146:Bony Callus / Q000502:physiology*; D016267:External Fixators; D005260:Female; D017102:Fracture Healing / Q000502:physiology*; D012756:Sheep; D013314:Stress, Mechanical; D013978:Tibial Fractures / Q000503:physiopathology* / Q000601:surgery*; D019415:Torque; D014102:Torsion Abnormality; D016474:Weight-Bearing