The invention provides a device and a method for exercising a user's leg whose lower leg tibial portion can be rotatably controlled during exercise. The device includes user-controlled rotatable drums connected to a sheet that surrounds a lower leg cuff for rotating and providing corrective forces on a user's knee joint during leg exercise. The device can be used with weight training equipment commonly found in commercial gyms, as well as in a user's home, or in clinics, to assist in rehabilitating malaligned knee joints.