CASTING TECHNIQUES for DO-IT-YOUR-SELFERS

Materials:

I have always used plaster of paris for my casts. Plaster bandages can sometimes be found at craft supply stores but they may be more expensive than buying them by the box from a medical supply distributor. You can also order by mail from Grogans or the Cast-Shop. I use rolls that are 4 to 8 inches wide and then cut them, if necessary, with a hacksaw. The rolls are easy to cut to various widths; you do have to trim the loose threads with scissors. In this way you save money by getting wider rolls and you can customize the bandage for different regions. For example, around your hand, you will need bandages that are only 2 or 3 inches wide for the first wraps. For longer regions, such as the calf or upper leg, you'll need bandages 4-6 inches wide. See what widths work the best for you.

Padding can be used to cushion the bony prominences around your foot, ankle and knee. There is a trade off between comfort and a snug fit. I like a snug fit myself, so I always use minimal padding. Some adhesive tape and cotton batting is usually enough around the ankle. If you're making a walking cast, the ankle bones are the most likely parts to be irritated when you put your weight on that leg, so some experimentation is necessary to find the right amount of padding that suits you. If you use a lot of padding, the cast will be heavier for a given strength because you have to use more plaster for each layer.

To cover the limb initially, stockinette is the ideal material but if you don't want to invest in that, other materials like long socks will work fine. The size of the stockinette refers to its width when it lays flat. For example if your ankle is 6 inches around (circumference) then 3 inch stockinette will just surround it without being stretched. It's best if the stockinette is stretched a little bit so that it will not have wrinkles when the cast material is applied. The maximum amount that stockinette can be stretched is about twice its initial size. For example, three inch stockinette can be used over a limb up to 12 inches around.

Measure around your foot, ankle, calf and thigh with a tape measure (or a piece of string). Refer to the chart below to find the proper size of stockinette. For arm casts, measure around your wrist and upper arm. Call this length L.

Stockinette Size Chart Dimensions in parens are (cm)
Minimum L	Maximum L	Stockinette Size
4"   (10.2)	8"   (20.3)	2"   (5.1)
6"   (15.2)	12"   (30.5)	3"   (7.6)
8"   (20.3)	16"   (40.6)	4"   (10.2)
12"   (30.5)	24"   (61.0)	6"   (15.2)

Since the thigh and ankle tend to differ by a large amount, you may need to use two different sizes of stockinette for long leg casts.

I have made some casts with no cloth covering at all by wrapping my leg first with crape paper. Crape paper is slightly elastic so you can wrap it like an elastic bandage. When it gets wet, it looses its elasticity and shapes exactly to your limb in a thin layer. Wet plaster will not soak through. Crape paper comes in very handy for long leg casts too, as I'll explain later.

For a walking cast, the walking heel is important. My first try was to use a piece of wood but that doesn't work very well because it's flat. You need something that is rounded on the bottom so it pivots when you walk. A thick stack of cardboard works good. Use the solid type of cardboard, not corrugated. Use tape to bind the layers together tightly so they don't slip when you put weight on it. By using varying sizes of cardboard for each layer, you can build up a heel that looks and functions like a real one. I have also made heels using silicone rubber (available at hardware stores). Make a mold out of plaster of paris using a form which can also be made from plaster of paris or wood. Coat the piece your using for the mold with a thin coat of grease or Vaseline. Pour in the silicone rubber and let it set for a few days. Now you have a nice rubber heel. The best way to get a professional heel is by mail-order from Grogans. For just a few dollars this will make a big difference in the quality of your walking cast.

Application:

A key thing is to not wet too much plaster at once so you can apply it carefully and smoothly. Apply the bandages in small section. I make two smaller rolls from each of the large ones, so I'm not pressured by the fast setting time. Only a modest amount of bandage is wetted at one time. This allows you to place the layers more carefully and smooth each one so that all layers are fused together. Smoothing is done with light pressure to avoid making a dent in the soft plaster. All layers must be well fused to make a strong cast. Plaster comes in several setting-speed categories. Get what they call 'fast setting', which is actually the slowest setting version and is easier to control.

Use a large bowl or a small bucket for the water. If you put a plastic bag, like a laundry bag or a garbage bag in the container, you won't have to clean the loose plaster off of it when you're finished. Just pour off the water that's left, lift out the plastic bag and throw it away.

To wet the bandage, first put your thumb under the loose end before putting the roll in the water. If you don't, the end is hard to find and you'll loose valuable setting time. Hold the bandage under water until the air bubbles stop rising. This takes only a matter of seconds. Pull the roll out and squeeze it gently to force out the excess water. Some of the plaster will be left behind in the container, but that's okay. If you don't leave the bandage in the water quite long enough, you can tell that the plaster looks partially dry as you roll the last part of the bandage. Moisten this part with water on your finger tips and smooth it down.

You can wrap the bandage in either direction but the roll must always be on the outside, away from your limb. When you are wrapping a tappered region, like your leg, start at the smaller part and work toward the larger part. Overlap the bandage about 50% as you go. Roll the bandage gently without putting tension on it. It should fit your contours but it must not squeeze your limb. You don't want to restrict circulation. By carefully rolling the bandage on, you will get a good snug fit but the diameter of your limb will still be the same as it was without the cast, so the blood flow is not affected.

Usually, leg casts are applied with the foot at a right angle to the leg. The medical reason is to keep the tendons between the leg and foot from getting shorter when the cast is worn for several months. This reduces the rehab time. You'll also find it is easier to walk, even with crutches, if your foot is at a right angle because you can put your foot down without jamming your toes in the floor.

The number of layers of plaster to use depends on several factors such as your weight and whether the cast is for walking or not. A walking cast needs to be reinforced on the bottom of your foot with extra plaster cut in pieces as long as your foot and applied like a plaster splint. Depending on your weight, you might need 15-20 layers in all. If you don't use enough, the bottom will collapse and the cast becomes uncomfortable because your foot is squeezed. Also, the cast will not be reusable. The proper thickness takes some experimentation. For a long leg cast, reinforce the bottom side of the knee and bottom part of your upper leg. When you sit in a chair there will be a lot of force on the back of your leg. If you want a heavy cast, you can just wrap more layers around your upper leg. I like to use plaster splints on the back and sides, so the total weight of the cast is not too great but I have strength where it's needed.

The outer layer of plaster can be made very smooth by wiping it while it's still damp with a soft cloth, like an old tee-shirt.

Long Leg Casts:

Its easier to make and remove a long leg cast by yourself if you do it in two steps. First make a short leg cast and finish it. This is hard to do with a full leg cast because you have to be able to reach all the way around the bottom of your foot, not just touch your toes. After the short leg portion is done, wrap the calf with crepe paper and then apply the upper leg portion. Overlapping these two sections makes the cast strong and the crepe paper allows you to remove the upper section easily without damage so it can be reused.

Drying the Cast:

It takes about one or two days for a complete cast to dry. Until it is dry it is not nearly as strong, so you have to be careful during this time not to crush any part of it. The drying can be speeded up by using a hair dryer. Put a plastic bag, such as a clothes bag or a garbage sack with a hole in the end, over your leg and aim the hair dryer into the bag. The warm air will flow through the bag and stay close to the cast instead of being dispersed. Even with this procedure, it will take several hours to dry, but it helps.

Removing the Cast:

The ultimate tool is a cast saw, but if you don't want to invest in that, a hacksaw blade works quite well. Get one with coase teeth so the plaster won't clog it. Also, get a good quality blade because the plaster will quickly wear out a cheap one. You can wrap one end of the blade with tape to get a good grip and protect your hand. There are also special handles for holding a hacksaw blade by one end for sawing in tight places. The end of the blade is rounded, so it won't cut your skin. Turn the blade so it cuts as you pull it out of the cast. After cutting through the plaster, the cloth inside will probably not be cut completely. Start at the top end of the cast with scissors and cut the cloth as you start to pry the halves of the cast apart. I find it takes about 45 minutes to remove a short leg cast with this procedure. The ankle region is the tricky part. As you cut around the ankle, make the cut rounded rather than two lines that intersect at a sharp point. The rounded corner makes the cast stronger when you reuse it.

Others have reported that a Dremel tool works well for removing a cast. That would probably be ok as long as the cast wearer is the one operating the saw so he/she can feel where the blade is. Watch the motor rpm and don't get in a hurry. Even doctors have been known to cut patients when they used improper techniques.

Reuseable Casts:

Since it takes so long to apply a good cast, it's nice to be able to reuse it. I make my initial cast with only six or eight layers. Then I wait a few hours until it has a chance to partially dry so I can remove it without changing its shape. After removing it I can finish reinforcing it easily and it will dry faster when it's not on my leg. A short leg cast can be placed in an oven at about 200 degrees to bake it in an hour or two (don't put on the rubber heel yet). Then saw it apart again and you're ready to wear your completed and dried cast. A long leg cast can be dried faster when it's not on your leg by directing a hair dryer to blow through the cast instead of on the outside.

The cast can be reapplied in a few minutes with elastic bandages. If you don't like the color of the bandages (I like white better), they can be whitened using a product that you find in the grocery store where dyes for cloth are sold. This product is designed to bleach brightly colored cloth before it's dyed another color. It works much better than ordinary bleach. After whitening the bandages, they can be used for years. If you want to wear the cast for an extended time, you can use narrow strips of plaster to hold the halves together. Pieces about an inch wide and two layers thick will hold very well. This avoids increasing the weight of the cast each time you reuse it. The small pieces along the edges can be whittled down with a knife or hacksaw blade every once in a while to restore the basic shape of the cast along the seam.

Another way to reapply the cast with a 'like new appearance' is to hold the halves of the cast in place temporarily with a few small pieces of plaster. Then wrap the whole cast with crepe paper and wrap a plaster bandage over the paper. Overlap the plaster just as if this were a new cast and a single wrap will be very strong. When you remove it, the outer layer can be separated from the main cast and you can reuse again without having the weight build up.

Some of my casts I have had for several years. The size can be adjusted as required by building up the edge with narrow strips of plaster, or a thin piece can be sawed off to make the cast smaller. If it develops a crack someplace, that can be repaired too.

Happy casting -- JD