title: There is poor reliability of Böhler's angle and the crucial angle of Gissane in assessing displaced intra-articular calcaneal fractures.
abstract: BACKGROUND
  Two-dimensional measurements are used to describe displaced intra-articular calcaneal fractures (DIACF). Our study evaluates the performance of Böhler's angle (BA) and the crucial angle of Gissane (CAG) among orthopedic surgeons.
  
  
  METHODS
  Thirty-four pre- and post-operative lateral foot radiographs from patients with DIACF were shown to four orthopedic surgeons who measured BA and the CAG. The intra- and inter-observer reliability were calculated using the intra-class correlation coefficient (ICC). Additionally, we calculated frequency of consensus given an allowed discrepancy. We then determined the tolerance limit for each measurement.
  
  
  RESULTS
  The ICC for inter-observer reliability of BA was 0.83 in the first session and 0.77 in the second. The ICC for intra-observer reliability ranged from 0.83 to 0.98. For the CAG, the inter-observer ICC was 0.28 and 0.1 in the two sessions. Intra-observer ICC ranged from 0.16 to 0.67. With an allowed discrepancy of 20°, there was lack of consensus for BA in 37.5% and for the CAG in 59% of measurements on average. The 95% confidence interval for 90% agreement in BA involved a range of 76°. For CAG, the 95% confidence interval of tolerance for 90% agreement was 56°.
  
  
  CONCLUSIONS
  For BA and CAG, there is frequent disagreement among experienced observers, even given a wide tolerance range. We recommend use of caution when applying BA as currently measured in making treatment decisions for DIACF.
  
  
  METHODS
  Diagnostic, level III.
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States. Electronic address: jesse-otero@uiowa.edu.
authors.forename: Jesse E
authors.initials: JE
authors.lastname: Otero
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: Brian O
authors.initials: BO
authors.lastname: Westerlind
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: Saran
authors.initials: S
authors.lastname: Tantavisut
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Karam
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: Phinit
authors.initials: P
authors.lastname: Phisitkul
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: Craig C
authors.initials: CC
authors.lastname: Akoh
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Gao
authors.affiliation: University of Iowa Hospitals and Clinics Department of Orthopaedic Surgery and Rehabilitation, 200 Hawkins Drive, John Pappajohn Pavilion 01085 JPP, Iowa City, IA 52242 United States.
authors.forename: J Lawrence
authors.initials: JL
authors.lastname: Marsh
mesh_terms: D002111:Calcaneus / Q000000981:diagnostic imaging* / Q000293:injuries; D018409:Foot Injuries / Q000000981:diagnostic imaging*; D006801:Humans; D057072:Intra-Articular Fractures / Q000000981:diagnostic imaging*; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results