The proximal femur has four major groups of trabeculae, distributing the compressive and tensile forces from the femoral head into the femoral diaphysis through the femoral neck. Together these trabeculae create the Ward triangle. The individual trabecular groups include:
- principal compressive trabeculae
- principal tensile trabeculae
- secondary compressive trabeculae
- secondary tensile trabeculae
As osteoporosis begins, the small bridging trabeculae are resorbed and lead to accentuation of trabecular groups. It is during this stage Ward's triangle begins to become large and ill defined. In late stages even the principal trabecular groups are weakened. This concept is utilized in grading of osteoporosis by Singh et al.