In below-knee (transtibial) prostheses, pin-lock socket systems are one of the mechanical suspension methods used to attach the residual limb to the socket. This article has been prepared to provide information on the working principle and general features of the system. All prosthetic applications are planned individually in line with the specialist physician's report and prescription.
How Does the System Work?
In the pin-lock system, a pin (metal tip) is screwed onto the distal end of the liner worn on the residual limb. This pin engages with the shuttle lock placed inside the socket, creating a mechanical connection between the residual limb and the prosthesis.
The system opens and closes easily with the help of a simple mechanism. When putting on the prosthesis, the user seats the pin in the lock; when taking it off, the user releases the lock by means of a release button. Because this mechanism makes donning and doffing intuitive, it may also be an easy-to-learn option for people using a prosthesis for the first time.
Key Features
The general features of pin-lock sockets can be listed as follows:
- Mechanical suspension: The lock aims to provide a repeatable and secure connection throughout the day.
- Simple use: Inserting and engaging the pin in the lock is sufficient; no separate suspension sleeve or vacuum unit is required.
- Fewer components: The absence of a suspension sleeve simplifies the system and may reduce the number of parts requiring maintenance and replacement.
- Easy removal: Thanks to the release mechanism, the prosthesis can be removed quickly.
- Broad compatibility: Pin-lock applications are commonly preferred in below-knee prostheses and can be used with different liner systems.
Comparison with Other Suspension Methods
Besides the pin-lock, vacuum-based methods are also used to attach the prosthesis to the residual limb. In active vacuum systems, a pump unit creates continuous suction between the liner and the socket. In passive vacuum (suction) systems, a one-way valve expels air from the socket during walking, strengthening the connection.
Which suspension method is suitable depends on factors such as the structure of the residual limb, skin condition, activity level and the person's daily living needs. This assessment is made individually by the specialist physician and the clinical team.
Points to Consider in Daily Use
In pin-lock systems, regular cleaning of the liner and socket is important for maintaining skin health. Whether the lock mechanism and the pin are working properly should be checked from time to time. If redness, irritation or pain is observed on the residual limb, it is recommended to consult the healthcare institution that carried out the fitting.
This content is for informational purposes; you should consult your physician for diagnosis and treatment.
