How 3D Printed Casts heal Fractures

A bone fracture or broken limb needs to be set with a cast to keep bones in alignment, protect the limb, facilitate faster healing, recovery and prevent chronic pain. While healing time may vary between individuals and injuries, average recovery times are around six to eight weeks.

Healthcare providers may use computerized tomography (CT) scans, X-rays, or magnetic resonance imaging (MRI) to diagnose a patient’s condition. These methods can help determine what type of fracture the patient has and what treatment to pursue.

Traditional methods for placing casts on fractures use plaster or fiberglass. However, this type of cast has a many disadvantages that may be better addressed using a 3D printed cast.

What is a 3D printed cast? How may it help in the recovery of your fracture? This article addresses these questions and explores the benefits of this new casting method in bone fracture recovery.

What Are 3D Printed Casts?

A 3D printed cast is an orthopedic brace made to encase a part of your body, such as your arm, wrist, or ankle, to keep it stable and assist in healing.

3D printed casts can be made of different biocompatible materials, such as plastics. 3D printed casts are commercially available from ActivArmor. ActivArmor 3D printed casts are fabricated using acrylonitrile butadiene styrene (ABS), a thermoplastic commonly found in computer keyboards, electronic housings, pipe fittings and lego blocks.

Traditional casts are made from plaster or fiberglass. These materials have been effective in fixing fractures and broken bones, as they can be formed directly onto the patient. However, traditional casts have several disadvantages:

• Traditional casts are heavy – The weight of the plaster on your limb may put some strain on your muscles and make your movements uncomfortable.

• Traditional casts restrict movement – Traditional casts are often bulky and cumbersome, which can limit your movement. While having a fracture or broken limb already restricts your actions, traditional casts may limit your activities further.

• Traditional casts render the limb unreachable – Sometimes, areas enclosed by the shell will develop rashes or infections. You may encounter difficulty treating those areas as long as the cast is in place.

• Traditional casts are unsanitary – Fiberglass and plaster trap moisture and bacteria against the skin for weeks or even months.  You cannot clean areas under the cast unless the cast is removed.

• Traditional casts are not waterproof – While the shell is in place, the doctor may advise you to keep it from getting wet. Once the water gets into the cast, the plaster may break down.

• Traditional casts require saws to remove – Fiberglass and plaster require saws to be removed, which can result in burns or injuries, and can be scary.

• Traditional casts are not adjustable – Edema (swelling) and muscle atrophy are common with acute injuries like fractures. A fiberglass or plaster cast can get tight, causing pain and potentially compartment syndrome, which can result in the loss of the limb.  They may also get loose due to reduction in swelling or muscle atrophy, and not stabilize the fracture well enough for healing.

• Traditional casts are not reusable – Plaster and fiberglass have to be sawed off and re-applied at every exam/x-ray. This takes time for both the patients and staff, and adds a lot of medical waste.

ActivArmor developed 3D printed casts to address the limitations of traditional casts.

To make a 3D printed cast, you must get an accurate 3D external image of the body part. ActivArmor uses iPhone hardware and software to make this imaging process available to everyone. Then a custom design must be done for each patient – based on their doctor’s prescription for their injury, and fitted exactly to their native anatomy to ensure precise immobilization and comfort.

Once the 3D model has been designed, it is printed using a 3D printer. Thermoplastics are a common material used for this printing method. In the case of 3D casts at ActivArmor, ABS is most commonly used.

After printing, the 3D cast is then finished to ensure it is water-tight, strong, smooth, and biocompatible. 

Benefits of 3D Printed Casts

Individuals with fractures or broken bones may consider 3D printed casts over traditional plaster casts for the following benefits:

Made of Lightweight Materials

The ABS material used in most 3D printed casts weighs a lot less than plasters or fiberglass. This lighter weight allows the user to move more freely, and the strain on the limbs is reduced.

ActivArmor casts have holes or a spiderweb-like design that exposes the skin. Air passes through the holes on the casing and reaches the skin, allowing the skin to remain ventilated and letting sweat evaporate.  This feature lets the skin breathe, and water drain out so the skin can dry easily.

Ease of Access to the Affected Limb

3D printed casts provide accessibility to the affected area, especially when the injury needs to be cleaned or inspected.

For example, performing routine X-rays and checkups is easier with reusable casts made from plastic.

Comfortable Design

Because of the 3D printed cast’s lightweight material and how the shell is modeled to follow the shape of the limb or body part, this cast may be more comfortable than plaster casts.

The ability to customize the cast also means you can choose high-tech treatments like bone stimulators/ultrasound, muscle stimulators, and TENS units. It also allows for a more aesthetic design, making the cast look pleasing and unobtrusive.

Water-Resistant

ABS is known to be waterproof, unlike fiberglass or plaster. Thus, there is no need for extra caution when going around places with water, such as the pool or beach. You also do not need to worry too much if there is a sudden downpour.

Individuals with ABS casts also have an easier time taking a bath or cleaning themselves, as the plastic is sanitizable, unlike plaster and fiberglass. Being able to wash your hands during a global pandemic is a matter of safety and health!

Conclusion

When choosing the type of cast to apply on a fracture or broken limb, 3D printed ones appear to have more benefits over plaster and fiberglass.

3D printed casts are lightweight, comfortable, and waterproof. They allow easy access to the fracture for cleaning and inspection.

Designing and printing a 3D cast requires a longer process than plaster casts, so there is a 4-business-day turnaround with ActivArmor, so you’ll be in your temporary splint or half-cast that you’ll get at the emergency room or urgent care for an extra 4 days during the first phase of your injury.

3D printing is still a relatively new technology, so many providers are not aware of it or used to using it, even though ActivArmor has made it accessible nationwide via iPhone.  So the patient may have to advocate for it with their provider, as plaster or fiberglass have been used for hundreds of years and is readily available.

Some patients may not have Durable Medical Equipment (DME) coverage on their insurance plan, so a custom 3D printed cast might not be covered.  However, the cash cost is less than the 2 casts it normally replaces, so is still affordable.

Consult a physician or orthopedist for more information about fractures and the types of casts that may help heal broken bones, and contact ActivArmor to learn more about your options.