A vehicle seat restraint system includes a vehicle seat of a vehicle. The vehicle seat includes a leg-rest supporting lower legs and feet of an occupant of the vehicle seat. An in-vehicle occupant detection system identifies positions of the lower legs and the feet of the occupant. A restraint actuator is connected to the vehicle seat. A safety restraint element is extended by actuation of the restraint actuator from a stowed position proximate to the leg-rest into an engaged position wherein the safety restraint element contacts and restrains the lower legs and the feet of the occupant against the leg-rest, mitigating against occupant knee hyperextension due to leg straightening at an occupant knee joint.