At Orfit Industries we receive many questions about our low temperature thermoplastic materials, and we are happy to answer them here.
The thermoplastic materials we use to fabricate orthoses today are referred to as low temperature thermoplastics (LTTPs) because we activate them using relatively low heat (water between 60-70°C or 140°-170°F). This is in comparison to other high temperature thermoplastics which require higher activation temperatures ( greater than 100°C or 210°F). Low temperature thermoplastic materials can be placed directly on our patients while we are molding the orthoses, unlike the previous generations of therapists who used higher temperature products and had to create molds of their patient’s arms.
There are so many types and varieties of LTTPs available today. It is just as important to know and understand the correct orthotic design for your patient’s needs as it is to select a proper LTTP for the orthosis. This ensures that your fabricated orthosis is not only procedurally correct, but also supportive, durable, and comfortable as well. Patients will tend to be more compliant with a comfortable and proper fitting orthosis.
LTTPs became available in the 1960’s. The first LTTPs were made from rubber products and therapists working with these had good control of the material as they formed splints. But the material itself had minimal stretch and very little conformability (see glossary in question 4). It was hard to mold around bony prominences. Plastic LTTPs were introduced in the 1970’s. Plastic LTTPs are highly conforming materials, but these can be challenging to control. So, the manufacturers of these products tried combinations of plastic and rubber together. These LTTPs created well molded orthoses and offered a good amount of control. Newer concepts in polymer production and design greatly improved the strength and rigidity as well as the elasticity of the LTTPs. As technology improves, we will continue to see improvements in our LTTPs.
OR “If you could choose just one splinting material to cover all your splinting needs in the clinic, which one would it be?”
We get asked these type of questions all of the time. We are fortunate to have so many choices in thermoplastic materials today because one material will simply not cover all of our patients’ needs. We make rigid and strong anti-spasticity orthoses, as well as lightweight thumb supports. We fabricate long arm orthoses with materials possessing maximum resistance to stretch. We also make dorsally based hand and finger orthoses from very conforming materials. There is no thermoplastic material which will satisfy every requirement we have. We need to understand the properties, characteristics, and qualities of these low temperature thermoplastic materials in order to make the best choices in our orthotic fabrication.
Choosing the correct LTTP is easy when we understand what makes each material unique.
Here is a glossary of terms used to describe the characteristics of LTTP’s:
Rigidity refers to the strength of the material. High rigidity is necessary for large orthoses, specific diagnoses such as spasticity, and orthoses projecting large forces.
Memory is the ability of the material to return to its original size and shape after being stretched. This is an important concept when frequent remolding of the orthosis will be necessary, as in serial orthotic fabrication to increase extension or flexion over time. Memory makes the material more cost efficient. When working with materials possessing excellent memory, remember to let the orthosis harden sufficiently before removing or it will lose its shape rapidly. LTTPs with excellent memory may take longer to harden, so be patient!
Coating is applied to certain LTTPs to make them easier to work with and less likely to adhere together where no adherence is desired. Bonding is the ability of the material to stick to itself or to other materials. Non-Stick coated materials do not bond without having the coating removed. Non coated materials have very good bonding to themselves and other attachments. Orfit Industries calls all of its non-stick coated products “NS” (see question 9 for more info).
Conformability or drapability refers to the way the material conforms to the shape of the hand. Materials with high drapability work best with gentle handling as they conform easily to the arches or bony prominences by just placing the material on the patient. These materials work with gravity. Materials with low drapability require firm handling and are recommended for larger splints where this moldability is less important.
Resistance to stretch refers to the amount of resistance the material gives to being stretched when heated. High resistance means you must work slowly, firmly and steadily to stretch the material. Low resistance to stretch means you need to carefully control the material as it stretches. Too much pulling will make the material stretch out of control.
Activation temperature is the temperature at which the thermoplastic material becomes pliable for molding. If the water is too cool, the material will not become pliable. If it is too hot, the material will get overheated and sticky and become difficult to work with. The ideal temperature for most LTTPs is between 60-70°C or 140°-160°F. Please read the manufacturer’s instructions for use for each individual LTTP.
Perforations in the thermoplastic material allow for ventilation of the skin and make the material lighter in weight. Today we have choices ranging from percentages of perforations to various names of perforation patterns. Catalogs usually feature pictures which demonstrate the different perforation patterns. Always check to make sure the perforation style is suitable for the orthosis you are fabricating.
Thickness of an LTTP must be taken into consideration as well. Thinner materials such as 1.6 mm (1/16”) and 2.0 mm (1/12”) are better for smaller orthoses while larger orthoses may need thicker materials such as 2.5 mm (1/8”) or 3.2 mm (3/32”). Thinner LTTPs are activated more quickly and also harden more quickly than thicker materials, meaning they have a shorter working time. Thicker materials take longer to become soft and pliable but have a longer working time as well. Thicker materials can retain a lot of heat and must be cooled slightly before placing on the patient’s skin.
Working time describes the amount of time from when the material is fully heated to when it is cooled off. Novice clinicians may want to choose materials that have a longer working time while experienced clinicians can usually work quickly and accurately with LTTPs that cool and harden quickly.
Pre-cuts are ready to be heated and molded to your patient’s extremity. They are orthotic designs cut out of specific LTTPs and ordered by size (and/or Right and Left hand). Make sure you measure your patient correctly for each design.
Prefabricated and /or preformed orthoses have already been molded into a specific shape. These must be carefully fit to your patient’s extremity and some adjustments may be necessary. The advantage in these is that you may save time and effort. However, you may not get as good a fit as when you custom make your own orthoses on your patients.
LTTPs do have a limited shelf life as these materials are made from organic components that are vulnerable to environmental factors. UV rays, heat and humidity, bacteria and germs can all have a negative effect on the thermoplastic material causing breakdown. Always store your thermoplastic materials flat in a dry, dark place for maximum benefit.
Each product has a label indicating its expiration date which varies from three to five years, depending on the product. If your product has been sitting on the shelf for longer than the expiration date on the label, it may not perform as expected. It may become brittle, discolored and overly stretchy. So, it is important to carefully manage your inventory of materials and to adopt the first-in – first-out principle.
Here are some quick tips and hints to get you started!
Non-stick coated materials are excellent for orthoses that you wrap around the extremity, lightly pinch together during fabrication and then pop apart when cooled. This feature makes it easy to fabricate circumferential orthoses and allows you to use both hands for positioning while the material stays in place. Non-stick coated materials are easy for novice splinters and students to try because they will not stick to the towel, or themselves. And if mistakes occur, it is easy to correct any accidental bonding by running cold water over the product.
On the other hand, non-coated materials, or tacky materials, are best for orthoses where you plan to apply outriggers or attachments because you will be able to create a very strong bond. These also might be better for patients who are not able to sit still during the fabrication process (due to uncontrolled muscle spasms) as these adhere a bit to the skin. This might make the fabrication process easier as the splint actually stays in place!
The NS coating is also very durable: it will not tear at spots where the coating of competing products might get damaged after being stretched frequently and/or excessively. The NS coating is skin-friendly as it is water-based and not based on solvents.
The Orfit splinting materials that are currently being treated with an NS coating are: Orfit NS, Aquafit NS, Orfilight NS, Orfit Colors NS, Orfit Eco Black NS and Multifit NS.
We hope these questions and answers have you understand more about our low temperature thermoplastic materials and how to work with them. Please feel free to ask us more questions as they arise! We are here to help!
Written by Debby Schwartz, OTD, OTR/L, CHT
Physical Rehabilitation Product and Educational Specialist at Orfit Industries America.
Debby is a certified hand therapist with over 36 years of clinical experience. She completed her Doctorate of Occupational Therapy at Rocky Mountain University of Health Professions in 2010. She has worked at Orfit Industries America as Product and Educational Specialist since 2007.
Debby is also an adjunct professor at the Occupational Therapy Department of Touro University, School of Health Sciences, and at the Occupational Therapy Department at Yeshiva University, Katz School of Science and Health in NYC. She has written many book chapters in the field of hand therapy and multiple articles for hand therapy journals, including the ASHT Times and the Journal of Hand Therapy. She has published a new textbook on orthotic fabrication together with Dr. Katherine Schofield, entitled “Orthotic Design and Fabrication for the Upper Extremity: A Practical Guide”.
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