Effect of conformity and contact stress on wear in fixed-bearing total knee prostheses

A patient-specific wear prediction framework for an artificial knee joint with coupled musculoskeletal multibody-dynamics and finite element analysis

“…Thirdly, due to the lack of the relevant patient specific ligament properties, generic values were taken from the literature, and the ligament origin and insertion points were located manually to fit the patient's bone geometries according to anatomic descriptions. Fourthly, although the wear model has been verified with experiments [1,46,54], the predicted wear volumes were 31%-45% lower than the experimental results [32], and the experimental simulator results may be even smaller than the retrieved TKR [55]. The improvement of the wear model may provide an even more realistic coupled framework.…”

“…The predicted in vivo knee joint forces and motions can readily be used to predict the surface wear of the TKR using the methodology already established [1]. All previous wear predictions have used fixed load/kinematics for the wear simulation of TKR, and not considered the effect of the change of kinematics/load due to tibial insert geometry variation caused by wear [30][31][32][33]. The use of fixed load/motion in the wear simulation means that the change of these input conditions, which affects the multi-directional cross-shear motion [34,35], has not been considered.…”

Wear of knee prostheses

“…Increasing rotation increased cross-shear and wear rate. 16,21 An increase in anterior-posterior displacement increased the surface area exposed to increased cross-shear, again increasing surface wear ( Figure 5). …”

“…In considering improved design solutions for polyethylene in the knee, we have modified Archards law 15 and introduced a new wear equation for polyethylene: 16,17 wear volume = C × (sliding distance) × (contact area) f(cross-shear) × f(counter face roughness) × f(level of cross-linking) In particular, we have shown the wear rate is dependent on and reduces with reduced contact area, reduced crossshear, reduced surface roughness, and increased crosslinking. The primary relationship shows that the surface wear volume increases as the area of polyethylene being worn increases.…”

“…The primary relationship shows that the surface wear volume increases as the area of polyethylene being worn increases. [16][17][18][19][20] The wear rate of polyethylene increases with an increase in cross-shear. 21,22 At low cross-shear, associated with unidirectional motion, the wear rate is low; however, as cross-shear ratio increases to between 0.05 and 0.1 the wear rate reaches its maximum value.…”