The diagnostic accuracy of Böhler's angle in fractures of the calcaneus.
BACKGROUND
Böhler's historical tuber-joint angle of the calcaneus has been used since 1931. Surprisingly, there is a paucity of literature on its use.


OBJECTIVE
To confirm the normal range for Böhler's angle and determine the angle with the highest accuracy in the diagnosis of calcaneal fractures.


METHODS
A retrospective cohort study was performed. The study cohort comprised 424 patients spanning a 5-year period from April 2005 to March 2010. Böhler's angle was measured by two independent observers on lateral x-ray study using the digital angle tool from the Picture Archival and Communication System. Data were analyzed using Stata 8 statistical software package.


RESULTS
The mean Böhler's angle in patients without calcaneal fracture was 29.4°. In this group there was no difference in Böhler's angle between male and female patients, left and right feet, or across age. In those patients with calcaneal fractures, a Böhler's angle below 25° was moderately predictive of calcaneal fracture (sensitivity = 100%, specificity = 82%), an angle below 23° was highly predictive of calcaneal fracture (sensitivity = 100%, specificity = 89%), and an angle below 21° was strongly suggestive of calcaneal fracture (sensitivity = 99%, specificity = 99%). A Böhler's angle of ≤ 20° had the highest diagnostic accuracy.


CONCLUSIONS
A Böhler's angle of 20° or less is highly accurate in determining the presence or absence of calcaneal fracture. Böhler's angle serves as a useful screening tool in fracture diagnosis.
Department of Orthopaedic Surgery, The St George & Sutherland Hospitals, Sydney, New South Wales, Australia; Department of Orthopaedic Surgery, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; Department of Orthopaedic Surgery, The University of New South Wales, Sydney, New South Wales, Australia.
Joseph D
JD
Isaacs
Mohammed
M
Baba
Phil
P
Huang
Michael
M
Symes
Maurice
M
Guzman
Haren
H
Nandapalan
Terence
T
Moopanar
Steve
S
Marchalleck
Zoltan
Z
Szomor
D000328:Adult; D002111:Calcaneus / Q000293:injuries*; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
Böhler; Böhler 's angle; calcaneus; diagnostic accuracy; fracture; orthopedic surgery; os calcis; screening tool