title: Defining ulnar variance in the adolescent wrist: measurement technique and interobserver reliability.
abstract: OBJECTIVE
  The measurement technique for ulnar variance in the adolescent population has not been well established. The purpose of this study was to assess the reliability of a standard ulnar variance assessment in the adolescent population.
  
  
  METHODS
  Four orthopedic surgeons measured 138 adolescent wrist radiographs for ulnar variance using a standard technique. There were 62 male and 76 female radiographs obtained in a standardized fashion for subjects aged 12 to 18 years. Skeletal age was used for analysis. We determined mean variance and assessed for differences related to age and gender. We also determined the interrater reliability.
  
  
  RESULTS
  The mean variance was -0.7 mm for boys and -0.4 mm for girls; there was no significant difference between the 2 groups overall. When subdivided by age and gender, the younger group (≤ 15 y of age) was significantly less negative for girls (boys, -0.8 mm and girls, -0.3 mm, p < .05). There was no significant difference between boys and girls in the older group. The greatest difference between any 2 raters was 1 mm; exact agreement was obtained in 72 subjects. Correlations between raters were high (r(p) 0.87-0.97 in boys and 0.82-0.96 for girls). Interrater reliability was excellent (Cronbach's alpha, 0.97-0.98).
  
  
  CONCLUSIONS
  Standard assessment techniques for ulnar variance are reliable in the adolescent population. Open growth plates did not interfere with this assessment. Young adolescent boys demonstrated a greater degree of negative ulnar variance compared with young adolescent girls.
authors.affiliation: Shriners Hospital for Children and the Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, MO 63110, USA. goldfarbc@wudosis.wustl.edu
authors.forename: Charles A
authors.initials: CA
authors.lastname: Goldfarb
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Strauss
authors.forename: Lindley B
authors.initials: LB
authors.lastname: Wall
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Calfee
mesh_terms: D000293:Adolescent; D000365:Age Determination by Skeleton; D000367:Age Factors; D002648:Child; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D006132:Growth Plate / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D015588:Observer Variation; D012737:Sex Factors; D014457:Ulna / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014955:Wrist Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging