_applied sciences_  
_Article_  
**Comparative Analysis of Healthy and Cam-Type**  
**Femoroacetabular Impingement (FAI) Human Hip Joints Using the Finite Element Method**  
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**Citation**: [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON] [PERSON]; [PERSON], [PERSON] Comparative Analysis of Healthy and Cam-Type  
Footnote 1: [[https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci)]([https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci))  
both structures, the femur and the acetabulum, but mainly in flexion and internal rotation movements, although there is also adduction in some cases [4]. There are three types of FAI: Cam, Pincer, and Mixed. Cam-type impingement is often seen in young, athletic men [5]. It is caused by a non-spherical femoral head. Pincer-type impingement is more common in middle-aged and older women. It is caused by excessive acetabular covering [6]. Mixed-type impingement is a variant of the previous two FAI types [7]. An understanding of the impact of Cam-type FAI on mechanical hip joint loading was sought by several studies involving the Finite Element Method (FEM). The studies also sought to provide information on the relationship between cartilage degeneration and mechanical stimulus [8]. One of the first efforts to use the FEM was a study of the Cam-type impingement that focused on impingement and dysplasia during sitting and walking [9]. The research considered, for the femur head and cartilage, a parameterized spherical ball-and-cup FE model with uniform cortical shell, to study different alpha and lateral center-edge angles according to the degree of Cam FAI severity. The mechanical properties considered were isotropic and linear elastic for the bone and cartilage. Both activities produced von Mises stresses and contact pressures in the acetabular cartilages. The contact pressures and von Mises stresses ranged from 3.67 to 12.84 MPa and from 9.70 to 27.20 MPa, respectively, during stand-to-sit. In [10] the depths of penetration of the acetabular cartilage and labrum were examined. This suggested an extremely high curvilinear and radial penetration as a result of the idealized geometries. The FE model proposed in this case considered the same mechanical properties as in [9]. However, no von Mises stresses information was provided regarding the acetabular cartilage. Other authors [11] analyzed two patients with severe Cam FAI. These included Cam deformities. The latter demonstrated the load's adverse effect on the hip joint when standing or squatting. The hip joint geometry of the FE models proposed in this case were obtained from subject-specific computed tomography (CT) scan data for a variable cartilage thickness with orthotropic elastic modulus for the bone and isotropic behavior for the cartilage. The anterosuperior bone surface experienced the highest stress. This occurred beneath the acetabular cartilage when patients who had severe Cam FAI (15.2 \(\pm\) 1.8 MPa) sat or squatted. This contrasted with healthy control participants (4.5 \(\pm\) 0.1 MPa). In [12], an FE model of a Cam FAI caused von Mises stress and contact pressure in the anterosuperior cartilage (14.4 and 11.6 MPa, respectively) and labrum (14.7 and 16.4 MPa, respectively) during hip flexion. However, von Mises stress (28.2 MPa) and a peak contact pressure (20.6 MPa) were obtained during partial and full internal rotation of the hip. In this case, the subject's specific hip geometry was obtained by MR. Linear-elastic and isotropic were considered for the soft tissues. A later FE study [13] modified the parametric hip model [8] for an examination of the cartilage stresses that Cam FAI produces.