Fig. 2From: Pre-sliding technique to improve femoral neck system against the shortening: a retrospective cohort studyMirror the contralateral hip to the affected hip and measure the horizontal shortening of the femoral head set to the X-axis, the vertical shortening of the femoral head set to the Y-axis, and the upward shortening distance of the femoral neck axis Z = Ysin(θ) + Xcos(θ) (θ is the angle between the Y-axis and the femoral neck axis)Back to article page