ALPS® Silicone Technology

ALPS® recently introduced an innovative, skin-friendly silicone prosthetic liner for lower limb amputation. This liner provides a solution to some of the clinical problems and disadvantages of silicone in skin-contact applications due to the inherently high coefficient of static friction typical of silicone polymers.

History of Prosthetic Liners

Silicone liners have been used since the 1980s in the prosthetic industry because 2 component RTV silicones were commonly used in prosthetic facilities for several applications thanks to the ease of mixing and the room temperature cure as well as to the excellent detail resolution that silicone provides when molded.
Therefore, the first triple S sockets (silicone suction sockets) were developed in the 1980s with great success by simply using the 2-component silicones already readily available.
Afterward, the first non-custom silicone liner was developed using a matrix reinforcement at the distal end, making a more convenient, off-the-shelf version of the 3S liner.
In many respects, silicone seemed, at the time to be the ideal choice for prosthetic liners as it has the following desirable properties:

  • Easy to clean
  • Repels dirt
  • Does not stain
  • Does not retain bad odors
  • Has a high coefficient of heat transfer (cools the limb better)
  • Can be molded in very thin sections, resulting in very light liners
However, silicone's high coefficient of static friction caused skin blisters in patients with sensitive skin. Therefore approximately 25% of patients could not tolerate the long-term use of silicone liners.
The high coefficient of friction per-se would not be a massive problem if the modulus of elasticity of silicone were low enough to allow the skin to move when subjected to shear forces.
The modulus of silicone, though, is not low enough for many patients, resulting in skin blistering. Such blisters are prone to be a source of more severe sores, especially in patients with poor vascularity.
Over the years, different additives have been developed that are introduced in the silicone rubber formulation, which exudes from the liners and provides lubricity on the skin.
And thermoplastic gel liners have been developed with a much lower modulus of elasticity than silicones. Some, like the EasyGel liners, have a modified surface to eliminate sticking altogether.

ALPS® skin friendly silicone liners

Prosthetic liners manufacturers tried to solve the issues mentioned above by including additives to the silicone to reduce the coefficient of static friction; however, the exudate substance can collect dirt, exacerbating the risk of skin issues, and the prosthetic liner may become slippery.
ALPS' expertise in processing silicone allowed our engineers to develop a new manufacturing method that improved the friction characteristics of the silicone prosthetic liner.
The surface of the prosthetic liner has been modified to create micro craters that reduce the static friction without any additives, resulting in an entirely skin-friendly silicone.
Silicone with the modified surface layer reduces 80% of the coefficient of static friction, as shown in the graph below.
Alps Silicone Pro and SoftSil liners are manufactured using pure silicone. This makes our silicone liners suitable for a wide range of amputees, including elderly and vascular patients with a lower limb amputation.
The Silicone Pro and SoftSil stands alongside our liners manufactured in EasyGel, Grip Gel, and the newest High-Density Gel (Silicone Equivalent).

ALPS® prosthetic leg silicone liners: from the technology behind the material to the benefits for the amputee

ALPS silicone is lightweight, hypoallergenic, cool, additive-free, and creates only one-fourth the friction of regular silicone. The technology used to create this particular silicone is of fundamental importance, allowing ALPS to design and produce silicone liners for prosthetic legs, which can guarantee:

Freedom of Movement

Maximum Gentleness

Cooling Effect

Ease of Cleaning

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