Characteristics of anterior inferior calcaneal cortex.

•Screw purchase in dense thick cortical bone provides more screw holding power than in cancellous bone.•Anterior part of inferior calcaneal cortex was a long trapezoidal shape, well-defined border as thick, convex relief from medial-lateral walls..•In percutaneous screw fixation to anterior inferior calcaneal cortex, screw purchased in middle cortex is suggested as it is the thickest cortex.•Consideration on the width of cortex of anterior inferior calcaneus, 6.5 or 7.0mm screw can be accepted without extrusion out of the cortex.