title: Resistance to subsidence of an uncemented femoral stem after cerclage wiring of a fissure.
abstract: OBJECTIVE
  To compare: (1) the force required to initiate subsidence, and (2) the relative subsidence, of femoral stems implanted into intact femora, and then into the same femora in which an induced fissure had been stabilized by cerclage.
  
  
  METHODS
  In vitro, mechanical study.
  
  
  METHODS
  Femora (n=9) from 9 dogs.
  
  
  METHODS
  Femora were prepared for implantation of an uncemented stem. Stems were implanted with continuous and impact loading. After axial loading until a fissure occurred, the stems were extracted, and the fissure stabilized with double-loop cerclage. Stems were reimplanted, and reloaded to failure.
  
  
  RESULTS
  Mean±SD load to initiate subsidence in intact femora was 1706±584 N compared with 2379±657 N for cerclaged bones (P=.002). Mean relative subsidence of intact femora was 3.99±2.09 mm compared with 1.79±2.99 mm for cerclaged bones (P=.091).
  
  
  CONCLUSIONS
  The load to initiate subsidence is increased in femora that have fissured, then have been stabilized with double-loop cerclage, when compared with intact femora. The relative subsidence is not different between intact and stabilized specimens.
authors.affiliation: Department of Biomedical Engineering, North Carolina State University/University of North Carolina at Chapel Hill, Raleigh/Chapel Hill, NC, USA.
authors.forename: Ryan S
authors.initials: RS
authors.lastname: McCulloch
authors.forename: Simon C
authors.initials: SC
authors.lastname: Roe
authors.forename: Denis J
authors.initials: DJ
authors.lastname: Marcellin-Little
authors.forename: Peter L
authors.initials: PL
authors.lastname: Mente
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002102:Cadaver; D004285:Dogs; D019544:Equipment Failure Analysis; D005269:Femur / Q000503:physiopathology; D006622:Hip Prosthesis / Q000662:veterinary*; D011475:Prosthesis Failure