Surlyn Socket Designs for the Young Child

EUGENE BANZIGER, CP(C)


Surlyn sockets, or other thin-walled flexible socket designs, receive a great amount of attention from adult amputees. ISNY principles and many others are widely used internationally on lower-limb prostheses, especially the above-knee, with considerable success.

Surlyn is a clear, copolymer plastic which is extremely flexible and can be stretched easily when heated. When cooled the product is very strong and durable. The benefits to the patient utilizing this type of socket fitting are:

  • a cooler amputation limb because of ease of heat dissipation through thematerial
  • light weight
  • flexibility of the socket wall
  • improved comfort

It was a simple task to apply this successful adult technology to pediatric amputees. For several years, Surlyn sockets have been fitted to infants and young children up to the age of 5 years. Young wearers benefit greatly from a socket which is light and considerably cooler, and in return will increase their wearing tolerance and activity level with the prosthesis.

Ford Laboratories now fits most children with this technique, including below-knee, Syme's, knee disarticulation, above-knee, proximal femoral focal deficiency, belowelbow, including acheria, elbow disarticulation, and aboveelbow. Proximal femoral focal deficiency, above-knee and knee disarticulation sockets are essentially of the same design. Socket designs consist of a frame made from carbon acrylic which encompasses the distal part of a Surlyn liner. A medial strut connects a proximal ring, which allows for weight transfer to the knee/foot assembly, as well as giving the opportunity of attaching a Silesian suspension system. (Figs. 1 and 2 ). Three benefits are of particular importance:

  • The clear material allows for visual check of socket fit, which eliminates the guesswork of fitting and generally results in a well fitting, comfortable socket.
  • Adjustments can be accomplished easily by keeping the original plaster model and altering the circumference as required, within limits, to allow for growth, especially the circumferential measurement.
  • Minor socket adjustments can be accomplished easily especially in narrow sockets distally by simply removing the inner socket liner.

Occasionally parents or children did not like the window designs. A socket of the conventional design lined with Surlyn was then fitted and the results apparently increased wearing comfort. Surlyn is more comfortable as compared to the conventional polyester or acrylic designs.

Additional designs accommodate below-elbow and above-elbow amputees. The above-elbow socket is designed much like the above-knee. The Surlyn liner is capped distally, utilizing a medial strut which connects the distal part of the prosthesis with the proximal ring, which in turn allows for attachment of harness and cables. (Fig. 3 ). This frame technique is used in most prosthetic and orthotic designs. More than 35 fittings of this kind for children 8 months to 5 years have been achieved, including socket replacement.

This technique is no longer used for Syme's and below-knee amputees; only those sockets which work very well are fenestrated. All sockets are worn with a sock and have conventional suspensions.

Feedback from parents is very favorable. When parents are not quite sure of the benefits, their children may receive conventional sockets of Perlon glass-reinforced acrylic resin. Two such instances included proximal femoral focal deficiencies. At followup they requested the Surlyn design again. The children did not seem to be as comfortable in the conventional design and after changing back their wearing tolerances improved significantly.

Ford Laboratories, 106-11400 Bridgeport Road, Richmond, British Columbia V6X 1T2, Canada