title: Interfragmentary movements in the early phase of healing in distraction and correction osteotomies stabilized with ring fixators.
abstract: BACKGROUND
  Experimental analyses have demonstrated the impact of mechanical conditions on bone healing. In critical clinical cases the mechanical conditions may be even more demanding than those in experimental studies. This study set out to examine the gap movements in distraction and correction osteotomies and to determine the suitability of initial fixation.
  
  
  METHODS
  Interfragmentary movements, ground reaction forces, and stability (ground reaction force divided by interfragmentary movement) were measured in 18 patients with tibial osteotomies stabilized by Ilizarov hybrid constructs until either bone union or conversion to internal fixation occurred (9 distraction treatments, 9 correction osteotomies). Consolidation was determined by clinical evaluation and standard radiographic techniques.
  
  
  RESULTS
  In both groups cocontraction led to gap movements comparable to level walking. Although the in vitro stiffness was slightly increased in the correction constructs, the interfragmentary movement in vivo was initially comparable between the groups. Patients undergoing distraction returned later to full weight bearing than patients undergoing correction treatment. In the correction group the stability increased with treatment time, while in the distraction group the stability remained relatively small.
  
  
  CONCLUSIONS
  The in vivo mechanical conditions in challenging clinical cases appear far more demanding than those in experimental studies. In distraction, mechanical conditions at the defect appear to be more critical than during correction osteosynthesis. According to the persistence of shear motion, even after 80 days of treatment, it may from the clinical point of view be important to maintain interfragmentary compression during the whole healing process and thereby reduce shear.
authors.affiliation: Department of Trauma and Reconstructive Surgery, Charité, Campus Virchow-Klinikum, Humboldt University of Berlin, Augustenburger Platz 1, 13353, Berlin, Germany. georg.duda@charite.de
authors.forename: Georg N
authors.initials: GN
authors.lastname: Duda
authors.forename: Simon
authors.initials: S
authors.lastname: Sporrer
authors.forename: Michael
authors.initials: M
authors.lastname: Sollmann
authors.forename: Jan E
authors.initials: JE
authors.lastname: Hoffmann
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Kassi
authors.forename: Cyrus
authors.initials: C
authors.lastname: Khodadadyan
authors.forename: Michael
authors.initials: M
authors.lastname: Raschke
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D016267:External Fixators; D005260:Female; D005592:Fracture Fixation / Q000295:instrumentation / Q000379:methods; D017102:Fracture Healing; D006801:Humans; D018889:Ilizarov Technique / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D009068:Movement; D010027:Osteotomy / Q000295:instrumentation / Q000379:methods*; D018709:Statistics, Nonparametric; D013977:Tibia / Q000503:physiopathology / Q000601:surgery*; D013978:Tibial Fractures / Q000503:physiopathology / Q000601:surgery*; D016138:Walking