A prosthetic liner can help improve prosthetic socket fit in several ways. When rolled on, the liner acts as an interface between the residual limb and the socket, helping distribute socket loads across the skin and underlying soft tissue.

It can also help shift friction away from direct skin contact and reduce shear at the skin interface by absorbing some shear forces applied through the socket.

Together, these functions may help protect the skin, improve comfort, and contribute to suspension of the prosthesis. The liner is also a crucial part of the suspension system, forming the connecting interface between the human body and the prosthesis.

Choosing the right liner for any individual is important.  Factors like residual limb skin condition, scaring, invaginations, residual limb length and shape, soft tissue amount and consistency, prosthetic suspension method, user activity level and hand dexterity, and even environmental factors play a role in choosing a liner.

There is no single liner that is best for everyone, and for an individual amputee there may be more than one appropriate liner option. It all comes down to the aforementioned variables as well as the preferences of the user and the clinician.

Liner selection is also heavily influenced by the type of socket material and socket shape that is chosen for the prosthesis. 

The choice of liner needs to reflect the suspension method of choice, and both of these will have an impact on the socket fit.  Making a change to one of these three factors (liner choice, suspension method, or socket fit) may affect the others. 

This means that a socket made for a Locking liner with Pin-Lock suspension might not always be suitable for a Seal-In liner with an expulsion valve and vacuum suspension, etc.

Choosing the right liner and suspension method is something that should be done with utmost consideration by the clinician and the user, as it provides the basis for a good socket fit.

Perspiration inside a prosthetic liner is something a lot of amputees experience.  Amputees typically experience this most after being fit with a liner and a prosthetic device.  In many cases this initial phase might last 2-4 weeks, after which perspiration will be less of an issue. 

However– when engaging in strenuous activities and/or living in a hot climate, the perspiration is always an issue for amputees. Taking off the liner regularly and drying off the skin and the liner before putting it back on can help maintain comfort and suspension. 

Some users have also benefitted from using an antiperspirant on the skin of the residual limb to limit perspiration.  New solutions like the Aerofit system are designed to help amputees manage perspiration inside their prosthesis. 

The three main suspension methods for liners: Pin-Lock, Cushion, and Seal-In all have their own advantages and trade-offs. 

Pin-Lock suspension relies on a pi—screwed into the distal end of the liner—engaging a lock embedded in the prosthetic to create suspension. 

• This mechanical suspension is the most commonly used for amputees all over the world.
• There are different types of pins, and most of them will emit a clicking sound when the user enters the lock in the bottom of the socket.  This audio feedback is very assuring for the users as they can clearly hear that the prosthesis is suspended and the mechanical connection is established. 
• There are other Pin-Locks that do not emit a clicking sound when the pin enters the lock, but they provide feedback and confirmation of connection through a kind of resistance when the user is entering the socket. 
• The trade off with a Pin-Lock is the fact that it takes up build height in the prosthesis which is not always desirable. 

A Cushion liner does not rely on a Pin-Lock for suspension and might be a solution in the cases where build height might be restricted. 

• Instead of the Pin and the Lock, a Cushion liner is normally paired with a sleeve and an expulsion valve creating vacuum suspension.
• Cushion liners are mostly used for transtibial amputees, as they are used with a sleeve covering the proximal part of the socket, extending onto the thigh as well. 
• The trade-off with a cushion liner is that the sleeve needs to cover the knee area, which might restrict knee flexion for some users.

The Seal-In liner combined with an expulsion valve in the socket, also relies on vacuum to create suspension of the prosthesis. 

• It does not need a sleeve and is therefore suitable both for TT and TF amputees. 
• It does not utilize a Pin-Lock either, which means that it can be a very good option in the cases where there is limited build height available.