Fig. 11

Histories of the force and moment components during the AP test at 30° knee flexion. Changes of all the force and moment components during the constrained AP test (a CT), and unconstrained AP tests using (b) FPH, (c) FPA and (d) FPHFM. While the constraining forces (PD and LM) and moments (VV and IE) were quite large during CT with RMS values of up to than 35.4 N and 0.82 Nm, respectively, their values were greatly reduced during unconstrained tests (b–d). The FPHFM and FPA were able to keep the constraining forces and moments close to the measurement accuracy, with RMS values of less than 2.8 N and 0.15 Nm, respectively, and the RMS values of FE angles less than 1.55°. The FPH had RMS values of up to 11.5 N and 0.45 Nm for the constraining force and moment components, respectively