A selectively lockable orthotic joint is provided in which a pressure sensor having a thin layer of variably resistive material generates a control signal when an actuation force is applied to the sensor. An electronic circuit operatively connects the sensor to a mechanical orthotic joint that can be selectively locked and unlocked in response to the control signal. The control signal may be uniform in strength selectively locking and unlocking the joint. The control signal may also be variable in strength wherein the orthotic joint provides increasing or decreasing resistance to motion responsive to a corresponding increase or decrease in control signal strength. The device is suitable for use as a foot/ankle/leg orthotic having a foot sensor which selectively operates a mechanical knee joint.