Wound Care Central NewYork
 

Total Contact Cast

 

As I mentioned on the page Diabetic Foot Wounds, one of the most important things we need to do when treating these wounds is to figure out a way to protect the wound from any pressure. While there are many ways to do this, the best, the “gold standard”, is a total contact cast.

 

Unless you’re familiar with wound care, you may well be surprised that casting has a role to play in healing wounds. It does, but it’s a different type of cast than one used to treat a broken bone. The purpose of a total contact cast is to transfer weight from the bottom of the foot to the lower leg. To understand how it does this, it helps to understand how it is different from a traditional cast.

 

With a traditional cast, the first step is to apply a lot ( ¼’ – ½” or more) of padding, followed by the plaster or fiberglass casting material. With a total contact cast, there is minimal padding. This allows the casting material to be carefully configured to the patient’s foot and leg. Because of this, when a person takes a step, the rigid cast transfers the weight from the bottom of the foot to the sides of the lower leg.

 

To get an idea of how this works, imagine a one of those sugar ice cream cones with a pointed tip. If you put the tip on a hard surface, it wouldn’t take much pressure on the top of the cone to crush the tip. However, if you put one cone inside another, you can press on the top cone with quite a lot of pressure without crushing the tip. This is because the force is now distributed along the entire surface of the cone.

 

If you look at the lower leg, it is essentially cone-shaped. Because of this, a rigid, closely conforming cast can transfer weight from the bottom of the foot up along the outside of the leg. In fact, pressure measurements with and without a total contact cast show that using a cast reduces pressure on the bottom of the foot by 85%.

 

Another reason casting may be so successful is that it stays on continuously. There are other types of boots and footwear that can protect the foot and reduce pressure on a wound. Most of these don’t reduce it as much as a total contact cast will, but the bigger problem is that people take them off. While people have the best of intentions, it is very easy to forget to put the boot back on before walking or to say “it’s only a few steps and I’ll walk on my heel” and start walking without the protection. Unfortunately, even a light step or two is enough to undo a days worth of healing.

 

 

Another effect of a total contact cast is to slow people down a little. One study put pedometers on people and looked at how many steps they took before and after they had the cast applied. They found that on average people walked about half as far as they normally did once the cast was applied. While I’m big on recommend walking and exercise, when you’re trying to get a foot wound to heal, slowing down a little can be a good thing.

 

One concern with using a total contact cast is that we are putting a closely fitting cast on somebody with a neuropathy who won't be able to tell if the cast is too tight somewhere or if a pressure point is developing. For this reason, it's important that everyone, both patient and caregivers, have a high index of suspicion and a low threshold for removing the cast. If there's any question at all, the cast should be removed.

 

Also, it's important to realize that most healthcare professionals are much more familiar with traditional cast than a total contact cast. A standard cast is padded heavily everywhere so when it's time to take it off you can use saw anywhere without much concern. That isn't the case with a total contact cast.

 

Now I don't want you to be afraid of a cast saw. The blade doesn't spin like a wood-cutting circular saw. Rather it vibrates back and forth. It will really only cut rigid material. If you press against something soft and mobile the soft material will tend to move with the saw blades rather than be cut by it.

 

However, it's still good idea to only in an area that has padding underneath. This is especially true if the cast is on someone who has problems with wound healing (which by definition includes anyone who needs a total contact cast). For this reason we always give our patients with total contact cast written instructions on how to remove the cast to carry with them at all times. This is in case (God forbid) they wind up in an emergency room somewhere for whatever reason and need to have the cast taken off.

 

Fortunately, that's never happened to any of the patients at our clinic.

 

When we decide to use a total contact cast the usual routine is to perform standard wound care, cleaning and debride the wound as necessary, apply an antiseptic dressing followed by foam padding over the wound and then the cast. We do the first cast change in two days just to make sure there's no problem with the cast. Then the cast is changed once a week. This allows for inspection and cleaning of the wound and application of fresh dressing as well as assuring that there is no problem with the cast.

 

To see one way (there are many) of applying a traditional total contact cast click the link to: Total Contact Cast Application Video