Document Detail


A modification of Klein's Line to improve sensitivity of the anterior-posterior radiograph in slipped capital femoral epiphysis.
MedLine Citation:
PMID:  19568015     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Radiographs can diagnose slipped capital femoral epiphysis (SCFE) on the anterior-posterior (AP) pelvis view and the frog-leg lateral view of the hips. On the AP radiograph, the lack of intersection between a line drawn parallel to the superior edge of the femoral neck (Klein's Line) and the epiphysis confirms a slip. Despite broad knowledge of the Klein's Line principle, application is difficult and inaccurate, especially in mild cases. On the frog-leg lateral radiograph, Southwick head/shaft angle and Wilson percent epiphyseal displacement commonly quantify the slip. Here, we set out to evaluate the intraobserver and interobserver reliability and the efficacy of these methods. METHODS: Five separate observers on 2 separate occasions evaluated 30 AP and 30 frog-leg lateral radiographs of patients with unilateral SCFE for head/shaft angle, percent epiphyseal displacement, and width of epiphysis lateral to Klein's Line. RESULTS: We calculated the minimum difference required for 2 measurements to be considered different with 95% confidence ("minimum agreement difference"). For head/shaft angle, the intraobserver minimum agreement difference was +/-7.27 degrees and the interobserver +/-8.80 degrees; for percent epiphyseal displacement, the intraobserver was +/-7.18% and the interobserver was +/-7.27%; and for width of epiphysis lateral to Klein's Line, the intraobserver was +/-1.98 mm and the interobserver +/-2.16 mm. For each of these measures, the slipped hips significantly differed from the control hips (P<0.001 in all cases). Our analysis of the classical definition of Klein's Line--the lack of intersection between Klein's Line and the epiphysis as a sign of a slip--identified only 40.3% of slips. By modifying Klein's Line such that we measure the width of epiphysis lateral to Klein's Line, we improved sensitivity to 79% if a difference of 2 mm between hips indicated a slip. CONCLUSIONS: On the basis of our findings, head/shaft angle and percent epiphyseal displacement provide reliable and efficacious means of radiographic SCFE diagnosis. The classic definition of Klein's line fails to identify 60% of slips. We propose a modification of Klein's Line to improve sensitivity.
Authors:
Daniel W Green; Ngozi Mogekwu; David M Scher; Sheryl Handler; Peter Chalmers; Roger F Widmann
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Publication Detail:
Type:  Evaluation Studies; Journal Article    
Journal Detail:
Title:  Journal of pediatric orthopedics     Volume:  29     ISSN:  1539-2570     ISO Abbreviation:  J Pediatr Orthop     Publication Date:    2009 Jul-Aug
Date Detail:
Created Date:  2009-07-01     Completed Date:  2009-09-23     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8109053     Medline TA:  J Pediatr Orthop     Country:  United States    
Other Details:
Languages:  eng     Pagination:  449-53     Citation Subset:  IM    
Affiliation:
Division of Pediatric Orthopaedic Surgery, Hospital for Special Surgery, Weill Medical College of Cornell, New York, NY 10021, USA. greendw@hss.edu
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Child
Epiphyses, Slipped / diagnosis,  radiography*
Female
Femur Head / pathology,  radiography*
Femur Neck / pathology,  radiography*
Humans
Male
Observer Variation
Reproducibility of Results
Sensitivity and Specificity

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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