Fig. 2

Schematic diagram of the calcuation method. a The blue line is the proximal axis of the femur on the affected side, the red dot is the projection point T of the upper edge of the lesser trochanter on the proximal midpoint of the femur, the green line is the TA, the orange line is the RLL, the yellow line is the LL. b and c The blue color designates the known line segment and angle, green designates the neck length of the appropriate prosthesis models, and the red segment NT is the target to be solved