least a threshold pressure is sensed by the sensor and in an unlocked position when less than the threshold pressure is sensed by the sensor.

2. The method of claim 1 wherein said locking step locks said joint in the flexion direction.

3. A selectively lockable orthotic device for association with the leg of a person comprising:

a selectively lockable mechanical orthotic knee joint that is capable of flexion and extension movement and having a locking mechanism that includes means for rigidly locking the knee joint to prevent flexion and to permit extension of the knee joint when the knee joint is in a locked position and which locking mechanism permits flexion and extension of the knee joint when the knee joint is in an unlocked position;

a pressure sensor for sensingplurality of spaced teeth of the first plate. The second plate is mounted so that it is deflectable in an axial direction such that the plurality of spaced teeth of the second plate can engage the plurality of spaced teeth of the first plate when the electromagnetic coil is energized. The engagement of the first and second plates locks movement of the orthotic joint in at least one direction when the first and second plates are engaged.

In accordance with one embodiment, the first and second plates are complementary and each comprise ratchet plates allowing the orthotic joint to move only in one direction when the joint is in a locked position. More specifically, in one embodiment, when unlocked the orthotic joint is movable in a flexion direction and