A device for increasing the range of motion (ROM) of a patient's afflicted knee joint following total knee arthroplasty (TKA) comprising an apparatus for insertion onto the pedal of an existing recumbent stepper machine. The apparatus enhances the functionality of recumbent steppers by (1) increasing the ROM angle of the knee at every seat position by moving the patient's foot closer to the stepper seat and thus the patient's torso, and by (2) allowing more ankle flection and a deeper guard rail than the original pedal to help maintain heel contact with the apparatus throughout the session.