What are Liners?
The use of liners with artificial limbs is fairly new. The first liner, which was an Iceros liner, was introduced about 15 years ago. The Alpha liner is around 5/6 years old. There are now around 150 different liners on the market ranging in price from £20 to £700 for a bespoke liner. They currently take up approximately 30% of the budget for artificial limb components at Roehampton.
Socket liners can be custom made or stock items. They can be made from a variety of materials such as Pelite (a dense flexible foam), silicone or gels. Liners are generally much softer than the socket and are never rigid enough to support the amputee’s weight without the support of the socket. The liner therefore provides a softer interface with the socket and more accurate volume matching of the residual limb and the socket. Some liners are also designed to provide suspension of the prosthesis.
The socket will be attached or incorporated into the structure of the prosthesis.
TYPES OF LINER:
The main materials used for making liners are silicone, gel and urethane.
3 types of liners, with the two min types being Locking liners and cushion liners.
1. Locking liners
2. Cushion liners
3. Seal-in liners (very new product)
LOCKING LINERS
This is where a pin at the end (base) of the liner engages with a lock. There are four types of locking liner. The majority of liners issued are locking liners.The standard is the Isceros Liner, which is 2 mm think. This costs £140.Cushion liners
Don’t have a pin at the end (base). These tend to be used for patients with more sensitive stumps. They offer more protection for stumps with scare tissue or bony protrusions.
SEAL-IN LINERS
This liner is a move away from the locking pin. It has a sealing membrane which creates a seal. A valve lets the air out creating a negative pressure, offering a suction effect.
What function do we want liners to perform?Suspension – liners with locking pins hold the leg on
Protection - some liners minimise sheer (friction from skin moving against the liner). Diabetics are more prone to skin breakdown. Cushion liners can help protect scar tissue.
Stabilisation – of soft tissues
Facilitate increased activity
Cushioning
Improved durability
It is important to understand that different liners require different casting techniques. It is often necessary to change the socket if you require a change of liner. A liner’s performance is also dependent on the socket design. Until recently, liners have always been more readily available for below knee amputees, but more recently trans femoral (above knee) amputees have had greater access to liners. There is, however, still a more limited choice for above knee amputees.
The basis for this section was a presentation to the Roehampton User Group by John Sullivan, Prosthetist at Roehampton
