title: Assessment of a novel biomechanical fracture model for distal radius fractures.
abstract: BACKGROUND
  Distal radius fractures (DRF) are one of the most common fractures and often need surgical treatment, which has been validated through biomechanical tests. Currently a number of different fracture models are used, none of which resemble the in vivo fracture location. The aim of the study was to develop a new standardized fracture model for DRF (AO-23.A3) and compare its biomechanical behavior to the current gold standard.
  
  
  METHODS
  Variable angle locking volar plates (ADAPTIVE, Medartis) were mounted on 10 pairs of fresh-frozen radii. The osteotomy location was alternated within each pair (New: 10 mm wedge 8 mm / 12 mm proximal to the dorsal / volar apex of the articular surface; Gold standard: 10 mm wedge 20 mm proximal to the articular surface). Each specimen was tested in cyclic axial compression (increasing load by 100 N per cycle) until failure or -3 mm displacement. Parameters assessed were stiffness, displacement and dissipated work calculated for each cycle and ultimate load. Significance was tested using a linear mixed model and Wald test as well as t-tests.
  
  
  RESULTS
  7 female and 3 male pairs of radii aged 74 ± 9 years were tested. In most cases (7/10), the two groups showed similar mechanical behavior at low loads with increasing differences at increasing loads. Overall the novel fracture model showed a significant different biomechanical behavior than the gold standard model (p < 0,001). The average final loads resisted were significantly lower in the novel model (860 N ± 232 N vs. 1250 N ± 341 N; p = 0.001).
  
  
  CONCLUSIONS
  The novel biomechanical fracture model for DRF more closely mimics the in vivo fracture site and shows a significantly different biomechanical behavior with increasing loads when compared to the current gold standard.
authors.affiliation: Department of Surgery, Experimental Surgery and Regenerative Medicine, Ludwig-Maximilians-University Munich, Munich, Germany. sebastian.baumbach@yahoo.com
authors.forename: Sebastian Felix
authors.initials: SF
authors.lastname: Baumbach
authors.forename: Enrico
authors.initials: E
authors.lastname: Dall'Ara
authors.forename: Patrick
authors.initials: P
authors.lastname: Weninger
authors.forename: Anna
authors.initials: A
authors.lastname: Antoni
authors.forename: Hannes
authors.initials: H
authors.lastname: Traxler
authors.forename: Martin
authors.initials: M
authors.lastname: Dörr
authors.forename: Philippe K
authors.initials: PK
authors.lastname: Zysset
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015519:Bone Density; D001860:Bone Plates; D004548:Elasticity; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010027:Osteotomy; D011885:Radius Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D013314:Stress, Mechanical; D016474:Weight-Bearing; D055114:X-Ray Microtomography