A portable appliance (14) is worn by the user in various configurations, including as a splint to hold a body joint immovable, as a brace to permit the body joint to move through a controlled range of motion and as an exercise apparatus to impart resistance to the flexing and/or extension movement of the body joint. The apparatus (14) includes an articulating frame (16) composed of a first frame section (18) connectable to the first limb of a body joint and a second frame section (20) connectable to a second limb of a body joint. The two frame sections are interconnected together by pivot joint assemblies (22a) and (22b) to permit the frame (16) to articulate about a transverse axis (24) corresponding to the anatomical pivot axis of the body joint. A control plate (164) having adjustable stop pins (166) and (168) is mounted on the pivot joint assemblies to control the range of motion of the articulating frame (16). With the control plate (164) in place, various types of resistance units may be employed to resist relative movement of the frame sections (18) and (20) in either or both directions about the pivot axis (24).