title: Various methods for assessing static lower extremity alignment: implications for prospective risk-factor screenings.
abstract: BACKGROUND
  Accurate, efficient, and reliable measurement methods are essential to prospectively identify risk factors for knee injuries in large cohorts.
  
  
  OBJECTIVE
  To determine tester reliability using digital photographs for the measurement of static lower extremity alignment (LEA) and whether values quantified with an electromagnetic motion-tracking system are in agreement with those quantified with clinical methods and digital photographs.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Thirty-three individuals participated and included 17 (10 women, 7 men; age = 21.7 ± 2.7 years, height = 163.4 ± 6.4 cm, mass = 59.7 ± 7.8 kg, body mass index = 23.7 ± 2.6 kg/m2) in study 1, in which we examined the reliability between clinical measures and digital photographs in 1 trained and 1 novice investigator, and 16 (11 women, 5 men; age = 22.3 ± 1.6 years, height = 170.3 ± 6.9 cm, mass = 72.9 ± 16.4 kg, body mass index = 25.2 ± 5.4 kg/m2) in study 2, in which we examined the agreement among clinical measures, digital photographs, and an electromagnetic tracking system.
  
  
  METHODS
  We evaluated measures of pelvic angle, quadriceps angle, tibiofemoral angle, genu recurvatum, femur length, and tibia length. Clinical measures were assessed using clinically accepted methods. Frontal- and sagittal-plane digital images were captured and imported into a computer software program. Anatomic landmarks were digitized using an electromagnetic tracking system to calculate static LEA.
  
  
  METHODS
  Intraclass correlation coefficients and standard errors of measurement were calculated to examine tester reliability. We calculated 95% limits of agreement and used Bland-Altman plots to examine agreement among clinical measures, digital photographs, and an electromagnetic tracking system.
  
  
  RESULTS
  Using digital photographs, fair to excellent intratester (intraclass correlation coefficient range = 0.70-0.99) and intertester (intraclass correlation coefficient range = 0.75-0.97) reliability were observed for static knee alignment and limb-length measures. An acceptable level of agreement was observed between clinical measures and digital pictures for limb-length measures. When comparing clinical measures and digital photographs with the electromagnetic tracking system, an acceptable level of agreement was observed in measures of static knee angles and limb-length measures.
  
  
  CONCLUSIONS
  The use of digital photographs and an electromagnetic tracking system appears to be an efficient and reliable method to assess static knee alignment and limb-length measurements.
authors.affiliation: Department of Health and Human Performance, College of Charleston, SC, USA. anguyen@highpoint.edu
authors.forename: Anh-Dung
authors.initials: AD
authors.lastname: Nguyen
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Boling
authors.forename: Carrie A
authors.initials: CA
authors.lastname: Slye
authors.forename: Emily M
authors.initials: EM
authors.lastname: Hartley
authors.forename: Gina L
authors.initials: GL
authors.lastname: Parisi
mesh_terms: D000886:Anthropometry; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000517:prevention & control*; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D010781:Photography; D015203:Reproducibility of Results; D012307:Risk Factors; D055815:Young Adult