Body-powered prostheses (cables) usually are of moderate cost and weight. They are the most durable prostheses and have higher sensory feedback. However, body-powered prostheses are less cosmetically pleasing than a myoelectric unit, and they require more limb movement.

Prostheses operated by myoelectricity may give more proximal function and increased cosmesis, but they can be heavy and expensive. They have less sensory feedback and require more maintenance. They function by transmitting electrical activity that the surface electrodes on the residual limb muscles detect to the electric motor.

Hands (Terminal Devices)

The major function of the hand that a  prosthesis tries to replicate is grip. 

Prosthetic Components

The major components of a lower extremity prosthesis are the socket, a sock or gel liner, a suspension system, an articulating joint (if needed), a pylon, and a terminal device. The terminal device is typically a foot but may take other forms for water or sports activities.

Knee joint

The prosthetic knee must fill 3 functions: provide support during the stance phase of ambulation, produce smooth control during the swing phase, and maintain unrestricted motion for sitting and kneeling. The prosthetic knee can have a single axis with a simple hinge and a single pivot point, or it may have a polycentric axis with multiple centers of rotation.

The pylon  

The pylon is a simple tube or shell that attaches the socket to the terminal device. Pylons have progressed from simple static shells to dynamic devices that allow axial rotation and absorb, store, and release energy. The pylon can be an exoskeleton (soft foam contoured to match the other limb with a hard laminated shell) or an endoskeleton (internal metal frame with cosmetic soft covering).

Terminal devices ( feet)

 The 5 basic functions of the prosthetic foot are (1) to provide a stable weight-bearing surface, (2) to absorb shock, (3) to replace lost muscle function, (4) to replicate the anatomic joint, and (5) to restore cosmetic appearance. Prosthetic feet are broadly classified as energy-storing feet or non–energy-storing feet.

Non–energy-storing feet include the solid-ankle/cushioned-heel (SACH) foot and the single-axis foot. The SACH foot mimics ankle plantar flexion, which allows for a smooth gait. It is a low-cost, low-maintenance foot for a sedentary patient who has had a BKA or an above knee amputation (AKA).

The single-axis foot adds passive plantar flexion and dorsiflexion, which increase stability during stance phase.

The energy-storing feet are the multiaxis foot and the dynamic-response foot. The multiaxis foot adds inversion, eversion, and rotation to plantar flexion and dorsiflexion. It handles uneven terrain well and is a good choice for the individual with a minimal-to-moderate activity level. The dynamic-response foot is the top-of-the-line foot and is commonly used by young active adults.