What is a Socket?

The socket is the most critical element of the whole prosthesis because it forms the mechanical interface between the subject and the prosthesis. The quality of the fit is fundamental for the comfort of the wearer. If the prosthesis is uncomfortable to wear of difficult to use, the amputee will be less inclined to wear it.Socket fit is crucial because it is the sole means of load transfer between the prosthesis and the residual limb (stump).The socket can be either an integral part of the prosthesis or made of laminated or thermoplastic materials which are connected to the other hardware. Some established patients still use metal sockets and swear by them.The most common materials used in modern prosthesis are:

Laminated materials
The socket is made up of several layers of strongly woven fabrics such as carbon fibre and fibreglass laminated in resin using a vacuum to create a lightweight but strong and durable material. Almost any fabric can be laminated into a prosthetic socket.

Thermoplastic materials
Square sheets of material, generally polypropylene, are heated and then placed over a cast (normally a plaster of paris model) of the residual limb (stump). The thermoplastic is moulded to the cast and allowed to cool.Once the socket has been created, the liner locking mechanism is attached. This is the mechanism which attaches the socket to the liner which is worn against the skin of the residual limb (stump). This is only necessary for sockets using a locking mechanism for the suspension of the socket.

Some areas of the residual limb are able to tolerate pressure, but some are not. The walls of the socket should only press on the residual limb in areas that are able to tolerate pressure. It is difficult to ensure that a finished socket only presses against the load bearing areas without causing discomfort to the non load bearing areas.