a tool for disabled people who need additional support to maintain balance or stability while walking. It consists of a frame that is about waist high, approximately twelve inches deep and slightly wider than the user. Walkers are also available in other sizes, such as for children, or for heavy people. Modern walkers are height-adjustable. The front two legs of the walker may or may not have wheels attached depending on the strength and abilities of the person using it. It is also common to see caster wheels or glides on the back legs of a walker with wheels on the front. Treadmills Bodyweight-supported treadmill training (BWSTT) are used to enhance walking ability of people with neurological injury. These machines are therapist-assisted devices that are used in the clinical setting, but is limited by the personnel and labor requirements placed on physical therapists. The BWSTT device, and many others like it, assist physical therapists by providing task-specific practice of walking in people following neurological injury. Prosthesis A prosthesis, prosthetic, or prosthetic limb is a device that replaces a missing body part. It is part of the field of biomechatronics, the science of using mechanical devices with human muscular, musculoskeletal, and nervous systems to assist or enhance motor control lost by trauma, disease, or defect. Prostheses are typically used to replace parts lost by injury (traumatic) or missing from birth (congenital) or to supplement defective body parts. Inside the body, artificial heart valves are in common use with artificial hearts and lungs seeing less common use but under active technology development. Other medical devices and aids that can be considered prosthetics include hearing aids, artificial eyes, palatal obturator, gastric bands, and dentures. Prostheses are specifically not orthoses, although given certain circumstances a prosthesis might end up performing some or all of the same functionary benefits as an orthosis. Prostheses are technically the complete finished item. For instance, a C-Leg knee alone is not a prosthesis, but only a prosthetic component. The complete prosthesis would consist of the attachment system to the residual limb — usually a "socket", and all the attachment hardware components all the way down to and including the terminal device. Despite the technical difference, the terms are often used interchangeably. The terms "prosthetic" and "orthotic" are adjectives used to describe devices such as a prosthetic knee. The terms "prosthetics" and "orthotics" are used to describe the respective allied