2 Emergency Medicine residents, 2 board certified EM physicians, and 1 board certified radiologist prospectively reviewed x-rays and asked to determine if a fracture was present and to measure Boehler's angle and the critical angle of Gissane.

• Emergency physicians were 97.9% accurate in diagnosing calcaneus fractures (range, 97% to 99%) with a kappa value of 0.96.  
• When ROC curves for determining Boehler's angle (BA) and the critical angle of Gissane (CAG) compared to the gold standard the AUC for BA was 0.82 - 0.88 and for CAG was 0.45 - 0.67.
• The interclass correlation coefficient for BA was 0.84 (95% CI, 0.79 - 0.87) and for CAG was 0.52 (95% CI, 0.43 - 0.60).

• The mean and SD of Boehler's angle were 30 degrees C +/- 6 degrees (range, 14 degrees to 50 degrees).
  
• There was no difference in Boehler's angle between male and female subjects (P greater than .05) or between left and right feet (P greater than .05).

• If 28 degrees is taken as the lower limit of normal for Boehler's angle, 37 cases (31%) would be false-positive "abnormal."
  
• The use of 20 degrees as the lower limit may decrease the number of false-positive to three cases (2.5%)
• The use of 18 degrees (mean -2 SD) reduces the false-positive rate to less than 1% (one case)