title: Standardized standing pelvis-to-floor photographs for the assessment of lower-extremity alignment.
abstract: OBJECTIVE
  The objective of this cross-sectional study was to assess the intra-rater, inter-rater and test-retest reliability and concurrent validity of lower-extremity alignment estimated from a photograph [photographic alignment (PA) angle].
  
  
  METHODS
  A convenience sample of participants was recruited from the community. Radiopaque stickers were placed over participants' anterior superior iliac spines. One radiograph and one photograph were taken with the participant standing in a standardized position. The stickers were removed. After 30 min they were reapplied and a second photograph was taken. The hip-knee-ankle (HKA) angle was measured from each radiograph using customized imaging analysis software. The same software was used by three readers to measure the PA angle from each photograph from the first set twice, at least 2 weeks apart. One reader measured the PA angle from the second set of photographs. Reliability was tested using intraclass correlation coefficients (ICC(2,1)), Bland-Altman analyses and the minimal detectable change (MDC95). Concurrent validity was tested using a Pearson's correlation coefficient and Bland-Altman analysis.
  
  
  RESULTS
  Fifty adults participated (mean age 41.8 years; mean body mass index 24.7 kg/m(2)). The PA angle was 4.5° more varus than the HKA angle; these measures were highly correlated (r = 0.92). Intra-rater (ICC(2,1) > 0.985), inter-rater (ICC(2,1) = 0.988) and test-retest reliability (ICC(2,1) = 0.903) showed negligible bias (<0.20°). The MDC95 was 2.69°.
  
  
  CONCLUSIONS
  The PA angle may be used in place of the HKA angle if a bias of 4.5° is added. A difference of 3° between baseline and follow-up would be considered a true difference.
authors.affiliation: Bruyère Research Institute, Ottawa, ON, Canada. Electronic address: lsheehy@bruyere.org.
authors.forename: L
authors.initials: L
authors.lastname: Sheehy
authors.affiliation: School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada. Electronic address: derek@cookes.ca.
authors.forename: T D V
authors.initials: TD
authors.lastname: Cooke
authors.affiliation: School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada; School of Rehabilitation Sciences, University of Ottawa, Ottawa, ON, Canada. Electronic address: lmclea2@uottawa.ca.
authors.forename: L
authors.initials: L
authors.lastname: McLean
authors.affiliation: School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada. Electronic address: elsie.culham@queensu.ca.
authors.forename: E
authors.initials: E
authors.lastname: Culham
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D017760:Bone Malalignment / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D035002:Lower Extremity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010781:Photography; D011859:Radiography; D012015:Reference Standards; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Alignment; Hip-knee-ankle angle; Knee osteoarthritis; Photography; Radiography