A lot of people associate a broken bone with an awkward, uncomfortable cast that puts a strain on day-to-day activities. As orthopedic innovation progresses, though, so do cast options, helping limit the inconveniences that the healing process can create.
The power of plaster
The earliest evidence of bone fracture immobilization dates to 3000 B.C., when the Egyptians used splints made of natural materials and cloth wrappings, wax or resin to fasten a cast. Other areas of the world developed similar casting techniques over time, including the Romans, who used the injured individual’s dried blood to harden cloth bandages.
One of the most far-reaching and revolutionary casting techniques in history came from Paris at the turn of the 19th century. The practice, known as plâtre coulé, entailed pouring gypsum-based plaster on the injured extremity and encasing it in wood. However, these casts were very heavy and not breathable, often tethering the individual to their bed during recovery.
In the 1850s, a Dutch military surgeon, Anthonius Mathijsen, found that soaking linen strip bandages in a water and plaster mix created a cast that dried much more quickly and was significantly less heavy than the traditional plaster casts. These casts became standard during the following century, before fiberglass reinforced plastic casts were developed. Fiberglass casts are lighter, more water-resistant and more durable than plaster casts.
Cast on, cast off
OrthoOne
Dr. Michael Rerko
When considering what type of cast to put on a patient, doctors first look at the overall condition and placement of the fracture, as well as the patient’s age. Pediatric patients generally heal faster than adults, and certain bones heal faster than others.
Some fractures require surgery to install a metal plate or screws to help hold the injured bones in place as a cast is applied. Conversely, some fractures or sprains can be protected by a thermoplastic molded splint that usually only covers some or most of the circumference of the extremity, instead of a cast that covers the entire circumference of the extremity. These splints are also easy to remove and remold.
The physician will also monitor swelling and may put a splint on the patient while waiting for the swelling to subside.
“There’s a complication called Compartment Syndrome where you can get so much swelling in a cast or a splint that it could lead to nerve and muscle damage,” says Dr. Michael Rerko, an orthopedic surgeon at Orthopedic One. “High-energy trauma, like a motor vehicle accident or a fall from a height, can create more swelling.”
Another factor to consider is the patient’s activity level. For example, someone who enjoys swimming or playing sports often would benefit from a waterproof cast.
Additionally, a physician will consider the risk of creating sores, which could become infected on the extremity while it is in a cast. Rerko says this is particularly important for older adults who may have thinner skin.
“If it’s not padded in the correct place, you can get skin breakdown, so it’s good to have an experienced cast tech that will apply the cast,” he says. “If people have a skin tear at the same time as their injury, oftentimes, we will do something removable, where they could check on the wound.”
While a removable cast could be convenient for some, it may not be the best option for all patients.
“For a lot of kids, we don’t want them to remove it,” Rerko says. “So that’s a reason kids get casts oftentimes, when adults with a similar fracture get a removable split.”
In the works
Hispanolistic/iStock
The fastest-growing trend in cast development is the 3D-printed cast. 3D-printed casts are a relatively new concept and are thermoplastic-based and porous, making them light and breathable. Many are also removable.
To create these casts, the physician takes measurements of the affected extremity and sends them to the manufacturer, which then prints a custom-fitted cast. Like all casts, 3D-printed casts have drawbacks, the most significant being its lack of flexibility.
“3D-printed casts are pretty rigid, so they don’t always allow a lot of room for soft tissue swelling, and most of them get shipped two or three days after the measurements,” Rerko says. “So, if the swelling changes in two or three days, then the cast may not fit correctly.”
Another modern cast is the Exos cast. Like 3D-printed casts, these are removable, lighter and less obstructive than traditional fiberglass and plaster casts. What sets them apart from their 3D-printed cousins is the Exos’ foam interior and easy adjustability.
The cast, which has a slit running through it, is first heated to be molded to the patient’s extremity before cooling and hardening. The slit is then laced up, crisscrossed like shoelaces, and can be loosened or tightened with a knob. The foam interior is easier to remove and clean, and may reduce the odors associated with wearing a cast for several weeks.
“That’s what the 3D-printed casts are trying to replace, but they need to get to the point where the 3D printer is in the actual (physician’s) office so the doctor can print it right at that time, and then find some sort of 3D-printed material that you can adjust later on, instead of reprinting a new cast each time,” Rerko says. “This is why you see a bunch of different companies, but none of them have taken over the market and become widely adopted.”
Maisie Fitzmaurice is an editor at CityScene Media Group. Feedback welcome at mfitzmaurice@cityscenemediagroup.com.
