title: Clinical stability of slipped capital femoral epiphysis does not correlate with intraoperative stability.
abstract: BACKGROUND
  The most important objective of clinical classifications of slipped capital femoral epiphysis (SCFE) is to identify hips associated with a high risk of avascular necrosis (AVN)--so-called unstable or acute slips; however, closed surgery makes confirmation of physeal stability difficult. Performing the capital realignment procedure in SCFE treatment we observed that clinical estimation of physeal stability did not always correlate with intraoperative findings at open surgery. This motivated us to perform a systematic comparison of the clinical classification systems with the intraoperative observations.
  
  
  OBJECTIVE
  We asked: (1) Is the classification of an acute versus chronic slip based on the duration of symptoms sensitive and specific in detecting intraoperative disrupted physes in patients with SCFE? (2) Is the stable/unstable classification system based on clinical symptoms sensitive and specific in detecting intraoperative disrupted physes in patients with SCFE?
  
  
  METHODS
  We retrospectively reviewed 82 patients with SCFE treated by open surgery between 1996 and 2009. We classified the clinical stability of all hips using the classifications based on onset of symptoms and on function. We classified intraoperative stability as intact or disrupted. We determined the sensitivity and specificity of two classification systems to determine intraoperative stability.
  
  
  RESULTS
  Complete physeal disruption at open surgery was seen in 28 of the 82 hips (34%). With classification as acute, acute-on-chronic, and chronic, the sensitivity for disrupted physes was 82% and the specificity was 44%. With the classification of Loder et al., the values were 39% and 76%, respectively.
  
  
  CONCLUSIONS
  Current clinical classification systems are limited in accurately diagnosing the physeal stability in SCFE.
  
  
  METHODS
  Level III, retrospective diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Inselspital, University of Bern, Bern, Switzerland. Kai.Ziebarth@insel.ch
authors.forename: Kai
authors.initials: K
authors.lastname: Ziebarth
authors.forename: Stephan
authors.initials: S
authors.lastname: Domayer
authors.forename: Theddy
authors.initials: T
authors.lastname: Slongo
authors.forename: Young-Jo
authors.initials: YJ
authors.lastname: Kim
authors.forename: Reinhold
authors.initials: R
authors.lastname: Ganz
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D002648:Child; D002908:Chronic Disease; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007431:Intraoperative Complications / Q000175:diagnosis*; D007432:Intraoperative Period; D007593:Joint Instability / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D011237:Predictive Value of Tests; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D060048:Slipped Capital Femoral Epiphyses / Q000150:complications / Q000473:pathology* / Q000601:surgery; D013997:Time Factors