Proximal Femur Geometry and Mechanics
Centre of rotation (C) lies just below the greater trochanter tip.
Neck-shaft angle: 125°–135°.
Greater trochanter tip: ~2–2.5 times the femoral head radius from C.
Anatomical axis: 9° to midsagittal plane, 5°–7° to mechanical axis.
Resultant force (R): 16° to midsagittal plane.
M: Direction of abductor muscle pull.