All three measurement methods (direct, radiographic, cross-sectional) showed consistent changes in cortical width with rotation.
In the proximal and middle diaphysis, rotation in either direction (internal or external) decreased both medial and lateral cortical width in 70-100% of samples, by up to 2.2 mm (20% of cortical width)—indicating cortices are thickest in neutral rotation at these levels.
In the distal femur, internal and external rotation increased medial and lateral cortical width in 80-95% of cases, by up to 1.75 mm.
Exception: medial cortical width in the distal femur decreased with internal rotation in 80% of specimens, by up to 1.3 mm.
The cortical step sign reliably signals rotational malreduction, but the abstract concludes that the direction of malrotation (internal vs external) cannot be reliably determined from this radiographic sign alone.
All three measurement methods (direct, radiographic, cross-sectional) showed consistent changes in cortical width with rotation.
In the proximal and middle diaphysis, rotation in either direction (internal or external) decreased both medial and lateral cortical width in 70-100% of samples, by up to 2.2 mm (20% of cortical width)—indicating cortices are thickest in neutral rotation at these levels.
In the distal femur, internal and external rotation increased medial and lateral cortical width in 80-95% of cases, by up to 1.75 mm.
Exception: medial cortical width in the distal femur decreased with internal rotation in 80% of specimens, by up to 1.3 mm.
The cortical step sign reliably signals rotational malreduction, but the abstract concludes that the direction of malrotation (internal vs external) cannot be reliably determined from this radiographic sign alone.