Normal Böhler's Angle of the Calcaneum

The normal Böhler's angle (calcaneal inclination angle) ranges from 20° to 40°, with a mean value of approximately 29-35° in adults.

Normal Reference Values

The mean Böhler's angle in adults without calcaneal fracture is 29.4°, with no significant differences between male and female patients, left and right feet, or across age groups 1.
Research demonstrates that normal adult values typically range from 20° to 40°, with postoperative restoration targeting angles between 20.5° to 54.5° 2.
A Böhler's angle of 20° or less is highly accurate in determining the presence of calcaneal fracture (sensitivity 99%, specificity 99%), establishing this as the lower threshold of normal 1.

The mean Böhler's angle in children (birth to 14 years) is 35.2°, which is statistically significantly lower than the adult mean of 39.2° 3.
Pediatric reference values are important when evaluating calcaneal fractures in children, as adult normative data cannot be directly applied 3.

A Böhler's angle below 25° is moderately predictive of calcaneal fracture (sensitivity 100%, specificity 82%) 1.
An angle below 23° is highly predictive (sensitivity 100%, specificity 89%), while an angle below 21° is strongly suggestive of fracture (sensitivity 99%, specificity 99%) 1.
The angle serves as a useful screening tool, with ≤20° having the highest diagnostic accuracy for identifying calcaneal fractures 1.

Decreased Böhler's angle increases maximum tension values on the calcaneus and load on the subtalar joint, significantly raising the risk of subtalar arthrosis 4.
Restoration of normal Böhler's angle is a major surgical goal in calcaneal fracture reduction, as it directly impacts calcaneal strength and joint stress distribution 2, 4.
Overcorrection of the Böhler's angle does not appear to increase the risk of subtalar arthrosis, though undercorrection significantly increases this risk 4.

Plain radiographic measurement may be difficult to apply in complex calcaneal anatomy; CT imaging provides superior visualization and more reliable angle measurement 5.
The angle must be measured on true lateral radiographs to ensure accuracy, as oblique views can falsely alter the measured value 1.

Always compare bilateral feet when possible, as individual anatomic variation exists within the normal range 1.
In pediatric patients, use age-appropriate reference values rather than adult norms to avoid misdiagnosis 3.
The angle should be interpreted in conjunction with the crucial angle of Gissane (normal adult mean 113.8°, pediatric mean 111.3°) for comprehensive calcaneal assessment 3.