A mains electricity (AC-powered) device designed to continuously move the ankle joint (e.g., flexion, inversion/eversion) without patient assistance during continuous passive motion (CPM) exercise therapy usually following surgery or trauma to the joint. The device typically consists of a motorized carriage with straps to hold and move the leg/ankle, and an electrical control unit for the healthcare professional to set the variable range of motion and motion speed; digital displays, manual/automated safety capabilities, and other features may also be included. CPM is believed to stimulate articular tissues and circulation of synovial fluid, and to reduce joint oedema.