There are several different kinds of plaster casting material available.
The choice depends on the particular injury.
In a Stable fracture the cast is often only needed to protect the bone from further injury and limit movement a little at the fracture site. (A little movement stimulates healing, too much movement slows it down.)
Hence the moulding and fit is not as critical. It is also possible to make a removable cast or use pre made splints.
In an unstable fracture treated just with a cast, here the plaster cast is critical in holding the bone ends in a good position and as such the fit and moulding is very important.
Following an acute fracture swelling can be a problem and as such a "Backslab" is used, this does not have to go on the back of the limb.
This is made up of an underlayer of orthopaedic wool, with a slab of usually old fashioned white plaster of paris.
It does not encircle the limb, usually covering half or 3/4rs of the circumference of the limb. A bandage is applied to keep it well applied to the limb.
The "cut away" completed by the bandage allows for swelling.
"Backslabs" are usually temporary, used for a few days. They usually do not last longer than 2 weeks.
Plaster of Paris (Gypsum)
Plaster of paris is often used in acute , fresh fractures. The reason Plaster of paris (Gypsum) is often used in this setting, is because it is a lot easier to mould to get a snug fit without creating any pressure areas.
It is heavier and not as resilient as synthetic casts but still the prefered casting material for fractures requiring a snug fit and "moulding" over the fracture to keep the bones in a good position.
You should not get plaster of paris wet once the cast has set.
Often called fibreglass casts, this is a slight misnomer not all synthetic casts are made of fibreglass, some are made of polyester.
There are two main synthetic casting groups.
Standard synthetic casts (hard)
Softcast - Softcasts are used mostly for support or stable fractures in kids. Benefits of softcast include the ability to remove by unwrapping or cutting off the cast without the need for a plaster saw.
It is also possible to manufacture a "swimming cast" using softcast.
Plaster of paris (Gypsum) should not be placed in water it softens the cast and it will disintegrate.
Synthetic casts (hard) will normally not fall apart if they get wet or splashed. The problem is if the padding or underlay remains wet for a long time the skin may macerate. If you do get your hard synthetic cast moist or wet, dry it out with a hairdryer.
Wrapping your arm or leg in a plastic bag and sealing with tape or elastic bands should be avoided they often leak.
Commercially available cast covers (eg. Limbo) are available often within 24 hrs of ordering. They are very good in keeping the limb watertight and enabling showering, bathing and swimming on the surface of a pool eg. hydrotherapy.
It is possible to manufacture a truly swimming cast with softcast and a thin terry cloth underlay, this is only suitable for stable fractures.
Looking after your swimming cast.
The problem with swimming softcasts and water is not that the cast will disintegrate but that the skin will become soggy and macerate.
Ensure you flush out the limb with clean water to get rid of any dirt and wash out any pool chemicals. Dry out the limb if not in a warm climate use a hairdryer and ensure the cast dries totally.
Give the skin a break do not keep it soaked in water all the time
Flying in a cast
It is important if you are due to fly in a cast that you let your treating doctor and plaster technician know.
The two major issues when flying are swelling of the limb in the cast and the increased risk of deep venous thrombosis DVT (clots in the legs that can break off and go to the lungs). (DVT see below)
If you have flown before you may have noticed that your ankles and feet swell a little. This is due to changes in the air pressure and sitting for prolonged periods of time.
If you are in a complete cast the swelling may lead to increased pressure in the cast and circulation problems.
The different airlines all have different policies and advice, it is best to contact the airline you are travelling with and inform them if you are in a cast and enquire if they have any set protocols/ policies.
In general it differs if you are a short haul flight for 2-4 hours or a long haul flight. It differs if it is your arm or leg and if it is your leg, if the cast goes above the knee or is below the knee
In general for short haul flights most airlines will allow you to fly with a full cast (plaster of paris or synthetic) if the cast has been in place for more than 48 hours.
If you need to fly before this it is possible to prepare a cast for flight (see below).
If your cast is on your leg it depends if the cast starts above the knee or below the knee. ie if you can sit in a normal airline seat.
If the cast is above the knee and you are unable to bend the knee some airlines will insist you pay for 2 to3 seats to be able to elevate the limb on the seats. They say it is not possible to sit in the exit seats as you may obstruct the exit.
Preparing a cast for flight
If a full cast has been applied and you need to fly within 48 hours then it can be prepared for flight by splitting it the full length of the cast.
We often bivalve the cast then overwrap it with a self adhesive bandage that can be easily unwrapped if needed.
Note: if you are flying with an aircast boot or simialr ensure you let out a little air, as a drop in cabin pressure often leads to the air cells expanding in flight.
Deep venous thrombosis (DVT)
A DVT is a clot normally in the leg that can break off and go to the lungs.
It is rare, but in severe cases it can be deadly.
Your risk of developing a DVT is increased following any injury or surgery. Restricted mobility due to a cast on your leg and further restriction by the confnes of an aircraft increase the risk of DVT.
The way to reduce these risks is to remain well hydrated with water, avoid alcohol, keep as mobile as possible, keep wiggling your toes to help pump the blood out of the leg.
Your doctor may prescribe something to thin the blood.