Pin Locking Systems


Pin Locking System

One of the most common of all prosthetic designs is the pin locking system. No suspension sleeve is required with this system, instead a liner with a pin screwed into the lower end is what makes the connection to the socket. A shuttle lock is fabricated into the bottom of the socket which the pin liner inserts into locking the residual limb in place.

There is a simple unlocking mechanism which can be accessed at the bottom of the socket to release the pin from the lock. This design affords the amputee with ease of use and an actual feeling of security as they can hear and feel the pin lock into place.

Advantages of a Pin Locking System:

  • Provide a positive mechanical lock with auditory feedback for the user when the pin engages.
  • Relatively easy donning and doffing and can be done in a sitting position.
  • More forgiving with volume fluctuations. 


Disadvantages of a Pin Locking System:

  • Due to the pulling down action of the pin on the liner an elongation effect can happen at the bottom of the residuum and cause skin breakdown, but newer liners are reinforced with a matrix to avoid this from happening.
  • Wear and tear on liners.
  • When the pin is misaligned or the liner is donned incorrectly the locking mechanism will not be engaged, this might be difficult for someone not having the ability to bend down or with poor eyesight.
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