31 Heating Modifying

Heating and shaping thermoplastic materials is a common practice in prosthetics and orthotics to modify the shapes of test sockets and orthotic devices. Thermoplastic materials are plastics that may be heated and reshaped without changing the original chemical polymer. Common thermoplastics used in P&O are LDPE (low density polyethylene), HDPE (high density polyethylene), PP (polypropylene), Copolyer, PUR (polyurethane), Subortholene, PETG, Kydex, Pelite, and Plastizote.

As an orthotist-prosthetist, please keep in mind that heat modifications is usually your last resort. As we will learn in the clinical courses, we first want to look at WHY their is pressure in the listed area. Most of the time the pressure area of concern is due to a lack of control somewhere else. The RESULT is pressure where you see it, the CONTOL is somewhere else. While not part of this exercise in this course, please be mindful of this concept.

Aim for:

• Heat relief modifications that are free of bumps and have smooth transitions
• Avoids imprints on plastic by not touching the side that is heated

PPE

• Wear dry oven gloves while working with hot materials.
• Closed toed shoes should be warn in all lab areas

Procedure

• Measure/assess original shape.
• Use an object that has a shape that matches the desired resulting shape.
• Heat the side of the plastic that you want to stretch.
  • Do not touch the side of the plastic that you heat.
  • Pay attention to the color or opacity of the plastic.
• Place pressure on the area you want to stretch.
  • Do not touch the side of the plastic that you heat.
• Repeat with more heat until you obtain the desired shape.
• After use, all the heat gun or torch to cool.

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