EVA Liner (PP Lower Limb Prosthetic) Polypropylene Technology International Committee of the Red Cross

EVA Soft Liner Fabrication - Measurement L c C Take the measurements of the cast: 1.Small circumference ("c") distal; 2.The length ("L"); 3.Large ("C") circumference;

Trace a trapezoid on a sheet of 6mm EVA, according to the measurements taken on the cast, and add 3 cm on the length (distally). EVA Soft Liner Fabrication - Measurement

Trim the lateral and small (distal) end Cut the trapezoid from 6mm EVA & skive the lateral edges & distal edge to nothing (width of 12mm) EVA Soft Liner Fabrication – Skiving & Gluing

 Apply glue on the trimmed sides. You can put the EVA in the oven (120°C) to soften the EVA and dry the glue.

EVA Soft Liner Fabrication – Skiving & Gluing  Glue the lateral side to form a cone. Keep the trimmed small side on the outside of the cone and let it free of glue.  Talcum powder is sprayed into the cone and on the plaster model before inserting it in the oven. Small trim side on the outside

Thermoforming is done using the vacuum pump, on a vertical suction pipe. Heat-up the EVA cone in the oven at 120°C. EVA Soft Liner Fabrication – Thermoforming  Slip the cone onto the plaster mould keeping the welded line on the posterior side of the mould, until the trimmed small side coincides with the end-tip of the plaster mould.

Thermoforming is done using the vacuum pump, on a vertical suction pipe. EVA Soft Liner Fabrication – Thermoforming  Cover the mould with a plastic bag, close it securely below the mould with an elastic strap and switch on the vacuum pump.

EVA Soft Liner Fabrication – Trimming  The soft socket cool down for few minutes.  Remove the plastic bag.  Prepare a 6mm EVA to cover the bottom (distal) edge.  Apply glue on the trimmed edge and on the cover cap.  Heat the cap in the oven and mould it on the socket.  Cut the extra EVA and grind it smoothly.

 If needed, add a piece of EVA in the medial supracondylar depression, or any other area in need of a fill up.  Roll down a cotton stockinet over the liner and cover it with neoprene glue. EVA Soft Liner Fabrication – Reinforcement

 Prepare a 3mm EVA sheet to cover the cotton.  Trim one side of the EVA and apply glue on it as on all the surface of the EVA.  Put in the oven at 120°C for a few seconds. EVA Soft Liner Fabrication– Covering

 Cover the soft socket starting from the posterior side. Remove the extra EVA and grind it smoothly on the posterior side.  N.B. There are other ways, as valid as this one, to do this task.  To finish, cover the distal end with a 3 or 6 mm EVA, and grind smoothly. EVA Soft Liner Fabrication– Covering

Two options are possible for the manufacture of the soft socket. 1 st For a question of cosmetic, the soft socket can be done with 2 layers of 3mm EVA. 2 nd For patient with bony stump, with scars or just for comfort, the soft socket can be made of one 6mm EVA plus one 3mm EVA. EVA Soft Liner Fabrication– Two Options

Warning: One layer of EVA 6mm, without reinforcement, for a liner should not be considered an option. It is not durable enough and it compress much earlier then the two layers approach.