Amputee Resources: Liner Basics 101 | Lesson 3

Welcome back to Liner Basics 101!

In Lesson One, we explored the three base materials that aid liners in skin protection and suspension of the limb: urethane, silicone, and thermoplastic elastomer (TPE). – You can click here for a refresher. In Lesson Two, we explored Transtibial Liner Profiles. Today, we’re exploring the specific interface materials WillowWood uses for our liners and Transfemoral Liner Profiles.

Let’s jump right in!

First things first: The material on the inside of the liner that goes directly against the skin is called the interface material. How the material reacts is called flow and rebound. Specifically, flow refers to the speed at which the material moves to accommodate the soft tissue and hard bone structure under bodyweight pressure. Whereas, rebound refers to the speed at which the material returns to its original state when bodyweight pressure is removed.

Interface Materials

Classic TPE* Gel

  • High flow helps the Classic Gel adapt to uneven socket pressures.
  • Low rebound means the liner will maintain this adapted shape over time.
  • Extremely skin friendly gel with Vitamin E and mineral oil

Hybrid TPE Gel

  • Hybrid Gel features balanced flow and rebound, making it a great intermediate solution.
  • Durable gel with Vitamin E, mineral oil plus Kevlar®


  • Low flow prevents the silicone from migrating away from highly sensitive areas.
  • High rebound helps the liner maintain it’s original shape.
  • Has a custom blend of Vitamin E and skin conditioners

SmartTemp Silicone with Outlast®

  • Low flow prevents the silicone from migrating away from highly sensitive areas.
  • High rebound helps the liner maintain it’s original shape.
  • Absorbs heat from a residual limb to delay the onset of sweat.
  • As the skin temperature rises, the silicone softens for all-day comfort.
*Thermoplastic Elastomer


Patients may choose to switch between interface materials depending on the activity they are taking part in – this is called retrofitting. You can learn more about that in our next installment of Liner Basics 101. For now, let’s explore which interface materials you may choose based on your activity level:

  • Classic provides cushioned, soft support to the residual limb. Usually used for lower activity, tissue protection, or new amputees post-surgery who are acclimating to their amputation.
  • Hybrid provides the wearer with a comfortable, relaxed fit and provides the liner with longevity.
  • Silicone provides the wearer with the extra support throughout the day.
  • SmartTemp provides the wearer with heat management technology for high-activity days or for amputees who experience more sweat.

Transfemoral Liner Profiles

AK Classic

  • Extra protection provided on the outside distal end to protect the femur
  • Can only be worn in one orientation
  • Thin top edge for slim profile under clothing
  • WillowWood® logo on lateral side of residual limb, not front

Symmetrical AK

  • Extra protection provided all the way around distal end to protect the femur
  • Tapers up the liner and thins out at proximal end
  • Can be rotated to extend the life of the liner

Symmetrical 4.5 mm

  • Same features as the Symmetrical AK profile with an additional 1.5mm gel at walls of liner
  • Used for suction and vacuum applications
  • Offered only in cushion
  • This profile is fabric-free: Offered in fabric-free Alpha Duo® Liner or fabric-free Alpha SmartTemp® Liner

Symmetrical 6 mm

  • Protects the limb with an overall thickness of 6 mm throughout the liner
  • Offered only with Classic gel interface material
  • Can be rotated to extend the life of the liner
  • This profile is available with the Alpha Basic® Liner.

For information on retrofitting liners, and what the heck retrofitting even is, be sure to check back for our upcoming installment of Liner Basics 101!


2 responses to “Amputee Resources: Liner Basics 101 | Lesson 3”

  1. Jeff Witt says:

    I love the Smart Temp. It absorbs not only my heat but also the pounding on my very small residual limb.
    It’s awesome!

    • Lisa Watkins says:

      Jeff, thank you for sharing your positive experience with the Alpha SmartTemp Liner. We love to hear how Alpha Liners help people!

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