About prosthetic sockets

The prosthetic socket is a connecting device between the prosthetic limb and the residual limb. It is the human-machine interface between the prosthetic limb and the residual limb. According to ISO standards: (1) Transmission of vertical forces (support); (2) Transmission of horizontal forces (fixation); (3) Adsorption interface between patient and prosthesis (suspension).

People who have already installed prosthetic limbs will have a common problem, which is that the socket does not fit properly, which makes wearing the prosthetic limb painful or not wanting to wear the prosthetic limb. No matter how expensive a prosthetic limb is, no matter how good its performance is, it will still be a pile of scrap metal without a good socket to fit it. The quality of the prosthesis depends on the adaptability of the socket. If the socket is not suitable for the residual limb, no matter how good the parts are, they will not be able to fully exert their functions and advantages.

A good socket must meet the following points:

(1) Good suspension: The residual limb should be closely connected to the socket. Good suspension will increase the patient's stability during standing and walking and reduce energy consumption.

(2) Full contact between the residual limb and the socket: The residual limb and the inner surface of the socket must be in direct and full contact without any gaps.

(3) Let the lower end of the residual limb bear the maximum force: The lower end of the residual limb should be directly connected to the lower end of the socket, and the lower end of the residual limb should bear the maximum force as much as possible, giving full play to the rotational force of the lower end of the residual limb, so that the residual limb can directly feel the bottom, and it can also relieve phantom limb pain.

(4) The socket prevents the residual limb from blood circulation and nerve innervation disorders: the socket cannot restrict the blood circulation and nerve innervation of the residual limb. For example, the socket cannot be made too small, and the local area cannot put too much pressure on the residual limb.

(5) The socket should be easy to put on and take off.

(6) The overall size of the socket is usually slightly smaller than that of the healthy side: the prosthetic socket is not allowed to exceed the corresponding normal size of the healthy side. The residual limb may swell at the beginning, so its girth will be larger than the corresponding healthy side, but the residual limb will quickly become smaller than the healthy side through the atrophy of the soft tissue. Of course there are exceptions.

(7) The socket is easy to clean: the inner and outer surfaces of the socket should be processed very smooth to facilitate daily cleaning of the socket.

(8) The socket is easy to refit: the volume of the residual limb is not fixed, but will change, and it is very difficult to require the entire surface of the residual limb to remain in contact with the socket at all times; and the volume of the socket itself is also changing. Sockets made of foam plastics and silicone soft materials will lose elasticity and become larger over time; resin sockets will also undergo changes in color, shape, and strength caused by aging. Disjointed transitions from flexible to rigid sockets and holes machined to connect connectors will be known weak links. The refitting method is usually accomplished by pasting filling materials, such as foam plastic, on the side walls, lower ends and edges of the socket. However, the foam plastic should be processed carefully in advance so that it remains integrated with the original socket after pasting; otherwise, indentations will be formed on the residual limb or even damage to the residual limb.

(9) Socket durability: It is mainly affected by many factors such as the service life of the socket, mechanical load, the adaptability of the socket, the tolerance of the residual limb skin, the care and maintenance of the socket, the quality of spare parts and materials and their processing.

(10) The socket is light in weight: Whether it is an upper or lower limb prosthesis, its weight must be reduced as much as possible to control the prosthesis and reduce energy consumption.

To judge whether a socket is good or bad, as long as it meets the above points, it is considered a good socket. Of course, in actual practice, it is impossible to achieve 100% fit, and the requirements for prosthetic technicians are also higher.

Reference: China Clinical Rehabilitation Picture Source Network

Preview of the next article: Problems that often occur during the fitting process of prosthetic sockets

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