Fig. 1

The level of the anterior wall of the greater trochanter (dotted line) on anteroposterior view using the International Society of Biomechanics coordinate system. The simulated cut of the greater trochanter passes through the point 5 mm distal to the lateral ridge of the greater trochanter (a), giving a maximum thickness (t) of 10 mm. The cutting line was set based on the osteotomy line of the GT commonly used in hip joint-preserving osteotomies such as transtrochanteric rotational osteotomy and transposition osteotomy of the acetabulum [29, 30]