Design parameters dependences on contact stress distribution in gait and jogging phases after total hip arthroplasty

Polyethylene Wear is Related to Patient-specific Contact Stress in THA

“…According to the Archard/Lancaster relationship, a higher loading force is related to higher wear [1], as we also observed in this study (Table 1). Our observations confirm those of several clinical and theoretical studies suggesting increased wear is related to the lateral inclination of the acetabular cup [30,33,34,41]. A small lateral coverage of the femoral head by the acetabulum decreases the contact area and contributes to a nonuniform stress distribution with elevated peak contact stress [14,15,34].…”

“…Third, the model considers single-leg stance represents all loading positions. During routine activities, the hip force attains various directions and magnitudes [32] that will change the contact stress pattern [23,34]. Also, the effect of velocity friction during motion [1], the effect of crossshear [20], and differences in physical activity between patients [28] are not explicitly included.…”

“…1A). If we assume that the contact stress p is proportional to the radial strain of the polyethylene cup [24,34], it follows that [40],…”

“…Several studies have attempted to explain wear mechanisms using finite element [11] or elasticity analysis [33,34]. These models apply the Archard/Lancaster relationship to calculate the wear coupling behavior assuming that wear is proportional to contact stress, sliding speed, and a bearing couple-dependent wear factor [11].…”

“…The models suggest the geometry of the prosthesis, ie, the radius of the femoral head [25], polyethylene cup thickness [22], or cup inclination [33,34] and the contact surface properties, ie, femoral head roughness [5], influence wear. The wear rate assessed using these mathematical models [25,33,34,38] agrees well with the wear measured in a clinical study [20], suggesting an important role of contact stress in mechanical damage of the polyethylene surface. One study using a hip simulator [27] found increased total load related to greater wear, again suggesting a role of contact stress in wear.…”