Diagnostic Accuracy of Bohler's Angle in Calcaneus Fractures
Diagnostic Accuracy of Bohler's Angle in Calcaneus Fractures
A retrospective case control study was performed. Data were obtained from the hospital digital Picture Archival and Communication System (PACS) and through a review of medical records. The study cohort comprised 212 consecutive patients diagnosed with calcaneal fractures on computed tomography (CT) scan, spanning a 5-year period from April 2005 to March 2010. An additional 212 patients with normal lateral foot radiographs were used to determine the normal range. Additional information gathered included patient demographics, past medical history, mechanism and side of injury, and location of tenderness. The latter helped to ensure that all those labeled as "normal" did not have an undiagnosed calcaneal fracture. Böhler's angle was measured by two independent observers (orthopedic surgeons) on lateral radiographs using the digital angle tool from PACS. The surgeons measured angles for all 424 cases and were blinded to the final diagnosis. The average was calculated from the 424 pairs of Böhler's angle measurements. Approval was obtained from the relevant Ethics Committee.
Data were analyzed using Stata 8 statistical software package (College Station, TX). Continuous variables were compared using Student's t-test. Categorical variables were analyzed using Fisher's exact test. Statistical significance was set at p < 0.05. Diagnostic tables were constructed from all 424 patients.
Böhler's angle is formed by two intersecting lines on the lateral radiograph of the calcaneus: 1) the line connecting the apex of the anterior process with the apex of the posterior facet and 2) the line connecting the apex of the posterior facet with the apex of the posterior tuberosity. Figures 1, 2, and 3 illustrate the measurement of Böhler's angle in the normal and fractured calcaneus, respectively.
(Enlarge Image)
Figure 1.
Schematic radiograph illustrating the landmarks for the measurement of Böhler's angle. (A) Apex of posterior tuberosity; (B) apex of posterior facet; (C) apex of anterior process.
(Enlarge Image)
Figure 2.
Lateral foot radiograph illustrating a normal Böhler's angle of 30°.
(Enlarge Image)
Figure 3.
Lateral foot radiograph illustrating a flattening of Böhler's angle to 0°.
Patients and Methods
A retrospective case control study was performed. Data were obtained from the hospital digital Picture Archival and Communication System (PACS) and through a review of medical records. The study cohort comprised 212 consecutive patients diagnosed with calcaneal fractures on computed tomography (CT) scan, spanning a 5-year period from April 2005 to March 2010. An additional 212 patients with normal lateral foot radiographs were used to determine the normal range. Additional information gathered included patient demographics, past medical history, mechanism and side of injury, and location of tenderness. The latter helped to ensure that all those labeled as "normal" did not have an undiagnosed calcaneal fracture. Böhler's angle was measured by two independent observers (orthopedic surgeons) on lateral radiographs using the digital angle tool from PACS. The surgeons measured angles for all 424 cases and were blinded to the final diagnosis. The average was calculated from the 424 pairs of Böhler's angle measurements. Approval was obtained from the relevant Ethics Committee.
Statistical Analysis
Data were analyzed using Stata 8 statistical software package (College Station, TX). Continuous variables were compared using Student's t-test. Categorical variables were analyzed using Fisher's exact test. Statistical significance was set at p < 0.05. Diagnostic tables were constructed from all 424 patients.
Measurement of Böhler's Angle
Böhler's angle is formed by two intersecting lines on the lateral radiograph of the calcaneus: 1) the line connecting the apex of the anterior process with the apex of the posterior facet and 2) the line connecting the apex of the posterior facet with the apex of the posterior tuberosity. Figures 1, 2, and 3 illustrate the measurement of Böhler's angle in the normal and fractured calcaneus, respectively.
(Enlarge Image)
Figure 1.
Schematic radiograph illustrating the landmarks for the measurement of Böhler's angle. (A) Apex of posterior tuberosity; (B) apex of posterior facet; (C) apex of anterior process.
(Enlarge Image)
Figure 2.
Lateral foot radiograph illustrating a normal Böhler's angle of 30°.
(Enlarge Image)
Figure 3.
Lateral foot radiograph illustrating a flattening of Böhler's angle to 0°.