Hip structural analysis
fracture
ENDO, BENDING
At three regions of interest (ROIs), narrow neck (NN), inter-trochanter (IT), and femoral shaft (FS), bone geometric indices were assessed using the HSA program included in APEX software (v3.2, Hologic Inc., Waltham, MA, USA).The narrow neck (NN) region is the narrowest width of the femoral neck, the inter-trochanteric (IT) region is on the bisector of the angle between the axes of the neck and femoral shaft, and the femoral shaft (FS) region is 2 cm distal to the patient's lesser trochanter midpoint.In all three regions discussed above, the following HSA geometric indices were analyzed: Sub-periosteal diameter (cm); Endo cortical diameter (cm); Cross-sectional area (CSA) excluding soft spaces in the marrow and pores as a reflector of resistance to forces along the long axis (cm2); Cross-sectional moment of inertia (CSMI) which represents resistance to bending forces in a cross Section (cm4); Section modulus (Z) as maximal stress with bending forces index (cm3); Cortical thickness (cm); Buckling ratio (BR) which is the outer radius to wall thickness ratio that is an indicator of the susceptibility to fracture by buckling under compressive load; and the Neck shaft angle that is the angle of the long axes of the femoral shaft and the femoral neck.The coefficients of variation for NN, IT, and FS regions in our laboratory were < 3%.