Patent ID: 7909885

Claim:
An artificial joint comprising: (a) a stance-phase control system having a flexing axis, a control axis and upper and lower coupling elements, and a lock, wherein the lock engages or disengages with a flexing or an extension moment, respectively, generated about the control axis; and (b) a swing-phase control system comprising: a piston and cylinder assembly and linkage assembly, wherein the upper and lower coupling elements are each linked to a portion of the swing-phase control system such that the piston and cylinder assembly generates a resistance force against flexing, wherein a load line of the resistance force passing through an uppermost link of the linkage assembly to the upper coupling element defines a longitudinal axis, such that: ( 1 ) the shortest distance between the flexing axis and the longitudinal axis, and ( 2 ) the shortest distance between the control axis and the longitudinal axis are substantially equal when the artificial joint articulates about the flexing axis to an angle to disengage the lock so as to reduce a moment, about the control axis, generated by the swing-phase control system.