title: Early Weightbearing After Operatively Treated Ankle Fractures: A Biomechanical Analysis.
abstract: BACKGROUND
  No consensus exists regarding the timing of weightbearing after surgical fixation of unstable traumatic ankle fractures. We evaluated fracture displacement and timing of displacement with simulated early weightbearing in a cadaveric model.
  
  
  METHODS
  Twenty-four fresh-frozen lower extremities were assigned to Group 1, bimalleolar ankle fracture (n=6); Group 2, trimalleolar ankle fracture with unfixed small posterior malleolar fracture (n=9); or Group 3, trimalleolar ankle fracture with fixed large posterior malleolar fracture (n=9) and tested with axial compressive load at 3 Hz from 0 to 1000 N for 250 000 cycles to simulate 5 weeks of full weightbearing. Displacement was measured by differential variable reluctance transducer.
  
  
  RESULTS
  The average motion at all fracture sites in all groups was significantly less than 1 mm (P < .05). Group 1 displacement of the lateral and medial malleolus fracture was 0.1±0.1 mm and 0.4±0.4 mm, respectively. Group 2 displacement of the lateral, medial, and posterior malleolar fracture was 0.6±0.4 mm, 0.5±0.4 mm, and 0.5±0.6 mm, respectively. Group 3 displacement of the lateral, medial, and posterior malleolar fracture was 0.1±0.1 mm, 0.5±0.7 mm, and 0.5±0.4 mm, respectively. The majority of displacement (64.0% to 92.3%) occurred in the first 50 000 cycles. There was no correlation between fracture displacement and bone mineral density.
  
  
  CONCLUSIONS
  No significant fracture displacement, no hardware failure, and no new fractures occurred in a cadaveric model of early weightbearing in unstable ankle fracture after open reduction and internal fixation.
  
  
  CONCLUSIONS
  This study supports further investigation of early weightbearing postoperative protocols after fixation of unstable ankle fractures.
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Tan
authors.affiliation: Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Norachart
authors.initials: N
authors.lastname: Sirisreetreerux
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Paez
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Brent G
authors.initials: BG
authors.lastname: Parks
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Lew C
authors.initials: LC
authors.lastname: Schon
authors.affiliation: Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA lyn.camire@medstar.net.
authors.forename: Erik A
authors.initials: EA
authors.lastname: Hasenboehler
mesh_terms: D016512:Ankle Injuries / Q000601:surgery*; D000843:Ankle Joint / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000379:methods* / Q000592:standards; D006801:Humans; D011184:Postoperative Period; D011859:Radiography / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology*
keywords: early weightbearing; fracture displacement; hardware failure; postoperative rehabilitation; traumatic ankle fracture