thermoplastic orthotics

How to Use Low Temperature Thermoplastic Orthotics to Improve Patient Results

Orthotics, traditionally called splints, are used to protect, support and/or immobilize a body part (Static Orthotic) and to increase PROM or facilitate AROM (Dynamic Orthotic). Typically these orthotics are made from low-temperature thermoplastic materials. The material is heated in a 160F water bath for one minute which makes the plastic moldable. Once removed from the bath, the plastic remains moldable for approximately 3 minutes, at which point it returns to a rigid state and hopefully the desired shape.

Sounds simple, doesn’t it!

As you start your career, it may be appropriate to go back to the beginning. Back to the point in time when you decided to pursue a degree in physical therapy. Regardless of the impetus that led you to your decision, hopefully, a significant part of the reason you’re receiving your degree is the desire to have a positive influence on the lives of the patients you’ll be treating.

Coach yellingA challenge to that desire is current trends that reduce the time and/or number of treatments paid by insurers. Unfavorable change has resulted in the clinician becoming more of a coach for the patient, such as instructing in the proper exercises the patient needs to perform at home, to achieve optimal results.

The reality is that much of the rehabilitative process needs to occur outside of the clinic. Fostering patient compliance is key to achieving optimal results.

The scope of practice within physical therapy is broad. One area, orthotic fabrication, spans all age groups and includes the orthopedic and neurologic populations. An orthotic can provide a therapeutic effect between treatment sessions and long after a patient has been discharged.

A brief history of orthotics and splints

Low-temperature thermoplastic orthotics were preceded by splints made from high-temperature thermoplastics, leather, metal, and plaster of Paris. Regardless of the material, the process was time consuming and modifications to the splint, as the patient’s condition changed, were challenging. The introduction of low-temperature thermoplastics in the 1970’s allowed the therapist to quickly fabricate a splint that provided an intimate fit.

hiWhat makes splint fabrication challenging is accurately assessing what style orthotic will provide the best treatment for the patient while still having the orthotic dovetail with the patient’s lifestyle. An orthotic that doesn’t address both concerns will either be ineffective or will not be worn.

Case Study:

The first patient on your schedule this morning is a 78-year-old female with a diagnosis of carpel tunnel syndrome (CTS). The referring physician has requested a “thermoplastic wrist splint”. The patient’s history reveals a history of RA, otherwise unremarkable. She is active in a variety of local volunteer organizations, loves gardening and spends, “more time than I care to admit” emailing her seven grandchildren. She reports that her right hand “goes numb and aches” while using the computer, during the night, and often when she first wakes up.

After explaining the probable cause of her symptoms you also explain how an orthotic can help to alleviate them by reducing pressure over the median nerve. She immediately responds that she doesn’t want to wear a “heavy, bulky brace”. You let her know that the splint will be form fitted to her hand and as a result will not be bulky. You also inform her that there are options to decrease the weight of the orthotic. After she looks at a sample wrist orthotic in your clinic and realizes how light it is, she agrees to having one made for her.

Case study analysis: Splint properties

Material Handling Properties: There are two broad categories for thermoplastic handling: isoprene rubber and plastic. In general, the plastic materials are more conformable and have a high degree of stretch, while isoprene rubber is less conformable but has more control due to its resistance to stretching once it is heated.

Discussion/Decision: The patient reported that if she was going to wear any type of splint it needed to be comfortable. A plastic material, with a high degree of conformability, was chosen so that the orthotic provided an intimate, comfortable fit.

Thickness: thermoplastics are available in 1/16th, 3/32nd, 1/8th and 3/16th (Most wrist orthotics are fabricated from 1/8th-inch material.)

Discussion/Decision: Considering the activities of daily living the patient performs, the rigidity of either the 3/16th or the 1/8th-inch material provides was not needed. At the same time, the 1/16th inch material may not be supportive enough for her gardening chores. The compromise, 3/32nd inch, was chosen. While most wrist splints are made from 1/8th-inch material, the 25% weight savings of the 3/32nd-inch material would make the orthotic lighter, improving compliance.

Perforations: thermoplastic materials can be solid or have perforations. Perforations will reduce the weight of the orthotic and may provide ventilation, making it more comfortable to wear. Highly perforated materials will also reduce the amount of rigidity. Perforation patterns typically have a number associated with them: 1%, 2%, 13%, 19%, 42% etc. This number refers to the amount of material removed from the sheet.

Discussion/Decision: The patient was in favor of using a perforated material because the splint would “breathe”. A perforation pattern of 13% was chosen. The rationale for this decision was based on the patient wanting a thinner material (3/32nd) which compromised the rigidity of the material by 25%, while the 13% perforation pattern will reduce the rigidity/strength by another 13%. (Total of 38% reduction in the total mass of material compared to the typical 1/8th inch solid orthotic) A higher perforation pattern may not have given enough support during her more strenuous ADLs.

 Color: Splint materials are available in a wide variety of colors, such as charcoal (black) or lavender. Materials with printed patterns such as camouflage are also an option. The original, and most common color, for orthotics, is white. Color options are primarily for improving wearing compliance.

Discussion/Decision: The patient declined a white orthotic saying, “It would look like I just walked out of the Emergency Room.” The patient did like the Charcoal (black) material saying it wouldn’t be as noticeable out in public and it wouldn’t show the dirt as readily after gardening.

Case study analysis: Fabricating the splint

A pattern was cut from the splinting material: long enough to have the distal border reach the distal palmar crease, the proximal border 2/3rds the length of the forearm and the width enough to be semi-circumferential. A hole was cut approximately 50% the diameter of the thenar eminence. The pattern was heated, removed and the thumb-hole edge rolled back one fold to create a smooth edge. The material was reheated to allow the full working time of 3 minutes. Placing the heated material on the patient’s UE, the thumb hole was large enough to see a portion of the thenar crease, allowing the thumb free AROM. The distal border was folded back so it was ¼th inch proximal to the distal palmar crease, allowing full AROM of the metacarpal phalanges.

At the same time, the palmar area of the orthotic was molded to reflect, and support, the transverse metacarpal arch. The wrist was placed in 5 degrees of extension and the forearm area was molded to create a semi-circumferential trough. The proximal border was flared to just lift the edge off the patient’s skin, avoiding a potential point of pressure. Once the material was rigid enough to remove without losing its shape, the edges of the orthotic were dipped in the splint pan and rough surfaces smoothed to avoid any skin irritation. To secure the splint to the patient, three hook and loop straps were applied: one at the most distal, one most proximal areas of the orthotic and the third strap was placed so it was over the wrist.

The patient was instructed to wear the splint at night when using her computer and gardening. The follow-up therapy appointment was three days later and the patient reported a 75% reduction in symptoms. She stated the splint needed no adjustments and that it “really seems to be helping me.” The patient was discharged from therapy, with a scheduled doctor’s visit in two weeks.

Summary:

A properly fitted orthotic, fabricated with input from the patient and her lifestyle, resulted in her wearing the splint as prescribed and ultimately resolved the symptoms of her CTS. Orthotic fabrication is one of the most impactful tools therapists have in their treatment regime. The art and science of splint making is challenging and highly rewarding. More likely than not, your “Best Practice” in the coming years of your career should include the use of low-temperature Thermoplastic Orthotics.

About Bruce Curtis

Bruce Curtis

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