title: Cyclic loading of sacroiliac screws in Tile C pelvic fractures.
abstract: BACKGROUND
  To investigate the stiffness and strength of completely unstable pelvic fractures fixated both anteriorly and posteriorly under cyclic loading conditions, the authors conducted a randomized, comparative, cadaveric study.
  
  
  METHODS
  In 12 specimens, a Tile C1 pelvic fracture was created. The authors compared the intact situation to anterior plate fixation combined with one or two sacroiliac screws. In 2,000 measurements, each pelvis was loaded with a maximum of 400 N. The translation and rotation stiffness of the fixations were measured using a three-dimensional video system. Furthermore, the load to failure and the number of cycles before failure were determined.
  
  
  RESULTS
  Both translation and rotation stiffness of the intact pelvis were superior to the fixated pelvis. No difference in stiffness was found between the techniques with one or two sacroiliac screws. However, a significantly higher load to failure and significantly more loading cycles before failure could be achieved using two sacroiliac screws compared with one screw.
  
  
  CONCLUSIONS
  Although the combination of anterior plate fixation combined with two sacroiliac screws is not as stable as the intact pelvis, in this study, embalmed aged pelves could be loaded repeatedly with physiologic forces. Given the fact that the average trauma patient is younger and given the fact that the quality (or grip) of the fixation was a significant covariable for longer endurance of the fixation, this suggests that direct postoperative weight bearing could be possible if these results are confirmed in further research.
authors.affiliation: Biomedical Physics and Technology, Erasmus University Rotterdam, The Netherlands.
authors.forename: C M A
authors.initials: CM
authors.lastname: van Zwienen
authors.forename: Eric W
authors.initials: EW
authors.lastname: van den Bosch
authors.forename: G A
authors.initials: GA
authors.lastname: Hoek van Dijke
authors.forename: C J
authors.initials: CJ
authors.lastname: Snijders
authors.forename: Arie B
authors.initials: AB
authors.lastname: van Vugt
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D050723:Fractures, Bone / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D011631:Pubic Symphysis / Q000503:physiopathology; D012399:Rotation; D012446:Sacroiliac Joint / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery*; D012447:Sacrum / Q000503:physiopathology; D013314:Stress, Mechanical; D017211:Treatment Failure; D016474:Weight-Bearing