A prosthetic device has a movable body and foot member with an end effector for contacting an external surface. A base body is coupled to a first joint of the foot member. A compliant linking member is disposed between a second joint of the foot member and a first joint of the moveable body. The compliant linking member can be a spring or flexible beam. A passive linking member is coupled between a third joint of the foot member and a third joint of the moveable body. An actuator is disposed between the base body and the second joint of the movable body. The actuator can be a motor with an extension member. The compliant linking member extends during roll-over phase. The actuator acts to assist with the extension of the compliant linking member during roll-over phase to aid with push-off phase in the gait cycle.