title: Failure of locked design-specific plate fixation of the pubic symphysis:  a report of six cases.
abstract: OBJECTIVE
  Physiological pelvic motion has been known to lead to eventual loosening of screws, screw breakage, and plate breakage in conventional plate fixation of the disrupted pubic symphysis. Locked plating has been shown to have advantages for fracture fixation, especially in osteoporotic bone. Although design-specific locked symphyseal plates are now available, to our knowledge, their clinical use has not been evaluated and there exists a general concern that common modes of failure of the locked plate construct (such as pullout of the entire plate and screws) could result in complete and abrupt loss of fixation. The purpose of this study was to describe fixation failure of this implant in the acute clinical setting.
  
  
  METHODS
  Retrospective analysis of multicenter case series.
  
  
  METHODS
  Multiple trauma centers.
  
  
  METHODS
  Six cases with failed fixation, all stainless steel locked symphyseal plates and screws manufactured by Synthes (Paoli, PA) and specifically designed for the pubic symphysis, were obtained from requests for information sent to orthopaedic surgeons at 10 trauma centers. A four-hole plate with all screws locked was used in 5 cases. A six-hole plate with 4 screws locked (two in each pubic body) was used in one.
  
  
  METHODS
  Fixation for disruption of the pubic symphysis using an implant specifically designed for this purpose.
  
  
  METHODS
  Radiographic appearance of implant failure.
  
  
  RESULTS
  Magnitude of failure ranged from implant loosening (3 cases), resulting in 10-mm to 12-mm gapping of the symphyseal reduction, to early failure (range, 1-12 weeks), resulting in complete loss of reduction (3 cases). Failure mechanism included construct pullout, breakage of screws at the screw/plate interface, and loosening of the locked screws from the plate and/or bone. Backing out of the locking screws resulting from inaccurate insertion technique was also observed.
  
  
  CONCLUSIONS
  Failure mechanisms of locked design-specific plate fixation of the pubic symphysis include those seen with conventional uniplanar fixation as well as those common to locked plate technology. Specific indications for the use of these implants remain to be determined.
  
  
  METHODS
  Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Saint Louis University School of Medicine, St Louis, MO 63110, USA. moedbr@gmail.com
authors.forename: Berton R
authors.initials: BR
authors.lastname: Moed
authors.forename: Charles S
authors.initials: CS
authors.lastname: Grimshaw
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Segina
mesh_terms: D000059:Accidents; D000328:Adult; D001860:Bone Plates; D019544:Equipment Failure Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D046548:Pubic Symphysis Diastasis / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D012189:Retrospective Studies; D013193:Stainless Steel; D015599:Trauma Severity Indices; D016896:Treatment Outcome
chemical_list: D013193:Stainless Steel