Abstract: A crutch assembly capable of having its longitudinal dimension adjusted by a movable lower leg member selectively positionable between an outwardly extended position and an inwardly retracted position through operation of a trigger mechanism. The trigger mechanism either attaches or releases the lower leg portion relative to an elongated base of the crutch and prevents or allows movement of the lower leg portion between the extended and retracted positions due to force exerted on the lower leg member by a biasing spring or by gravity. The height of the crutch is thereby selectively adjusted for adaptation to different elevations of the surface over which a user travels such as when traversing steps, stairs, ramps, etc.