prostheses

A prosthesis is an artificial device that replaces a missing body part, designed to restore function and/or appearance after limb loss or congenital absence. Prostheses are most common for arms and legs but can also replace other structures such as fingers, facial elements, or teeth.

Prostheses are classified by location and purpose. Upper-limb prostheses include passive cosmetic devices, body-powered systems that use a harness and cables to operate a voluntary opening or closing terminal device, and myoelectric devices that use residual muscle signals to control electric motors. Advanced upper limbs may employ targeted muscle reinnervation or pattern-recognition control. Lower-limb prostheses include below-knee and above-knee devices, with a socket, pylon or shank, and a foot-ankle assembly. Modern options also include microprocessor-controlled knees and energy-storing-and-returning feet.

Key components include the socket, which fits over the residual limb; the suspension system that keeps the prosthesis in place; the pylon or frame; joints; and the terminal device for hands or the foot/ankle for legs. Manufacturing may involve plaster casts or digital scanning, careful socket alignment, and materials such as carbon fiber, aluminum, silicone, and various polymers. 3D printing is increasingly used to fabricate or customize components.

Fitting and rehabilitation require a prosthetist and a multidisciplinary team. The objective is comfort, proper fit, functional mobility, and gait training. Outcomes vary; prostheses can improve independence and reduce energy expenditure, but challenges include cost, maintenance, skin irritation, socket fit changes, and device durability. Historically, prostheses have evolved from simple mechanical devices to powered and computerized systems, with ongoing advances in materials, control algorithms, and interfaces, including future directions like osseointegration and neural control.