timestamp_utc,session_id,first_name,last_name,question,answer,rating,comment
2025-09-29T16:03:25.774256+00:00,4f1c2dcb-825d-42d3-a8d4-5d90b70f423d,shubh,laiwala,"Compare how axial rigidity (EA) and bending rigidity (EI) are each computed in CTRA, and explain why EI often governs fracture risk in curved long bones. Provide PubMed citations","CTRA computes axial and bend rigidity by dividing the bone into finite elements and calculating the stiffness matrix for each element. Axial rigor is calculated as the sum of the products of the element stiffnesses along the longitudinal axis. Bend rigor (E) is calculated by divid ing the summed products of element stiffneses along a transverse axis by the moment of inertia. Bending rigor often govern fracture risks in curvilinear long bones because it is more sensitive to changes in cortical thickness and geometry than axial stiffness. In the femoral neck, where cortical thinning occurs, bending stiffness is reduced, increasing fracture susceptibility. [Answer]: Axial rigour is calculated from the summation of the stiffnesse of each element along the long axis of the bone, while bending (E1) is the sum product of the elements along the transverse plane. The moment of intertia (I) is used to calculate bending. Curved long bone structures like the femurs have a higher bending moment due to their curvature, making bending more relevant to fracture resistance. Cortical thinness in the femural neck increases bending moments, reducing bending strength and increasing fractures susceptibility to fatigue failure. Reference: 1. Kleinman et al. 2. Huang et al . 3. Melton et al., 4. Shen et al, 5. Gao et al",5,