## 4 Results and Discussion  
Figures 7-9 show the results for the healthy and Cam-type femoroacetabular impingement hip joints FE models with a vertical load of 80 kg combined with an alpha angle of 50\({}^{\circ}\)  
Figure 6: (**a**) Proposed Cam-type FE model with the applied boundary conditions and (**b**) radiograph of the patient’s hip joint including a displacement and rotation of 50\({}^{\circ}\) of the femur in the Cam-type hip joints. Figure 7a,b shows, respectively, the maximum displacement and the von Mises stresses in the cartilage of the healthy hip joint FE model. It can be seen that the displacement and the von Mises stresses were, respectively, 0.1 mm and 2.41 MPa. In addition, Figure 8a,b shows, respectively, the maximum displacement and the von Mises stress on the cartilage of the Cam-type hip joint FE model. The results indicate that the maximum displacement of the cartilage was 0.437 mm, whereas the maximum von Mises stress was 6.9 MPa. The latter occurred on the anterosuperior bone surface, beneath the acetabular cartilage. This difference in the displacements experienced by the two FE models suggests that damaged cartilage undergoes a greater displacement of cartilage mass than healthy cartilage, which can produce direct contact between the femur bone and the pelvic bone. The damage that this type of pathology can cause over time can be significant. It can even result in direct contact between the head of the femur and the acetabulum of the pelvis, causing the patient to develop arthrosis. As has been observed, the malformation of the femur head (Cam-type) is the main cause of the increase in displacement and stresses on the cartilage. In normal conditions of the femur, this pathology should not occur. Figure 8: FE results for the cartilage of the Cam-type femoroacetabular impingement hip joint: (**a**) displacement and (**b**) von Mises stresses. Figure 7: FE results for the cartilage of the healthy hip joint: (**a**) displacement and (**b**) von Mises stresses. Figure 9a,b shows, respectively, the contact pressure distribution on the acetabular cartilages of both the healthy and the Cam-type femoroacetabular impingement hip joint. These figures show peaks of contact pressures in the superior region of the cartilage with values of 2.24 MPa and 9.65 MPa, respectively. for the healthy and the damaged cartilage. This difference in the localized contact pressures in the superior region of the cartilage is largely due to the fact that the head of the femur is not fully covered by the cartilage (femoral head coverage). The values of the stresses and contact pressures of the damaged FE model when the pathology is of the Cam-type are very similar to those that other researchers obtained when the applied load and alpha angle were similar to those in this paper (6.9 MPa). In [9], the authors obtained slightly higher von Mises stress values while patients were sitting and walking at 9.70 and 27.20 MPa, respectively. In the same way, the contact pressures obtained by the same researchers were also very similar to those obtained in the current work. The contact pressure peaks obtained by these researchers for the walking condition, with an alpha angle of 50\({}^{\circ}\) and a femoral head coverage angle of 0\({}^{\circ}\) (totally damaged cartilage) or 30\({}^{\circ}\) (undamaged cartilage), were 9.92 MPa and 3.55 MPa when walking. These are similar to the values obtained in this paper (9.65 MPa and 2.24 MPa MPa). Other authors [11] obtained von Mises stress values that were more in line with the results obtained in the current work, with 15.2 \(\pm\) 1.8 MPa while squatting for patients with the severe Cam type. For healthy patients, the stresses were 4.5 \(\pm\) 0.1 MPa. In this case, the maximum stress occurred on the surface of the anterosuperior bone, below the acetabular cartilage. Some authors [12] obtained an elevated peak of von Mises stress in the anterosuperior cartilage 14.4 MPa and labrum 14.7 MPa, during hip flexion. During partial and full internal rotation, the von Mises stress was 28.2 MPa.