title: Failure mode of transcondylar screws used for treatment of incomplete ossification of the humeral condyle in 5 dogs.
abstract: OBJECTIVE
  To investigate the mode of failure of transcondylar screws retrieved from dogs previously treated for incomplete ossification of the humeral condyle (IOHC).
  
  
  METHODS
  Metallurgical study.
  
  
  METHODS
  Broken screws (n=5) from dogs with IOHC.
  
  
  METHODS
  Broken transcondylar bone screws were retrieved from dogs that had apparently successful surgery for IOHC. Screws were measured and examined using scanning electron microscopy (SEM) and energy-dispersive analysis by X-rays (EDX).
  
  
  RESULTS
  EDX confirmed that screws were made from 316L stainless steel and there was no evidence of significant corrosion or manufacturing faults that might have contributed to implant failure. SEM of the fractured surface of screws revealed a similar and complex pattern of fatigue failure characterized by multidirectional fatigue cracks and the presence of several initiation sites. All screws had signs of fatigue failure because of multidirectional forces of variable magnitude.
  
  
  CONCLUSIONS
  Intercondylar instability is a feature of IOHC that persists despite placement of a transcondylar screw.
  
  
  CONCLUSIONS
  The pathogenesis of IOHC involves chronic intercondylar instability and its treatment using even relatively large transcondylar screws has a risk of late implant failure.
authors.affiliation: Croft Veterinary Hospital, Cramlington, UK.
authors.forename: E Alasdair
authors.initials: EA
authors.lastname: Charles
authors.forename: Malcolm G
authors.initials: MG
authors.lastname: Ness
authors.forename: Russel
authors.initials: R
authors.lastname: Yeadon
mesh_terms: D000818:Animals; D001848:Bone Diseases, Developmental / Q000601:surgery / Q000662:veterinary*; D001863:Bone Screws / Q000009:adverse effects*; D004283:Dog Diseases / Q000151:congenital* / Q000601:surgery; D004285:Dogs; D005552:Forelimb / Q000473:pathology*; D007592:Joint Diseases / Q000151:congenital / Q000601:surgery / Q000662:veterinary*; D010012:Osteogenesis