Fig. 4

A Comp 11 stress (stress in the x-axis direction). Stress generation by tensile stress around the medial side of the femur and compressive stress around the lateral side of the femur (compressive stress, 200 MPa). The possibility of damage to the medial side is low and that to the lateral side is also low, except for minute damage around the hole. B Comp 11 stress anterior hole case. Under stress distribution, at 2750 N, there is a high possibility of damage around the additional hole due to the medial compression force and lateral tensile force because of structural weakness and a high possibility of damage caused by cracking from the additional hole toward the outer hole. C Comp 11 stress posterior hole case. Under stress distribution, at 2750 N, there is a high possibility of damage around the additional hole due to the medial compression force, lateral tensile force, and structural weakness. D Center hole case. The possibility of damage is low around the medial side. However, breakage is highly possible when an additional hole occurs. The anterior hole case is the most vulnerable because the maximum stress is higher than in the posterior hole case, and the damaged area is wider