Fig. 15

Force-deformation curves during VV tests. The force–deformation curves from the first trial of the constrained VV tests (CT, thin grey dotted line) and unconstrained VV tests using FPH (thin black dash-dotted line), FPA (thick grey dashed line) and FPHFM (thick line) at (a) 0° and (b) 30° flexion. FPA and FPHFM had similar measured stiffness both for valgus/varus both at 0° and 30° knee flexion during AP tests while those measured using CT and FPH were different. During CT where significant constraining forces and moments were required, the target moment was reached with smaller angular displacement, indicating less laxity, when compared to those of the unconstrained tests using the three unconstrained control methods