In the case of acute trauma to the forearm and hand, or lower leg and foot, which is accompanied by pain and swelling in or near the joint and for which a definitive treatment cannot yet be administered, application of a plaster splint can be considered.
For example, in the case of a sprained ankle, it is often impossible to clinically establish whether it is a second degree (partial rupture) or third degree sprain (total rupture) or a fracture. In both cases, the RICE approach should be applied, followed by immobilisation using a (plaster) splint providing the position of the limb is normal. If subsequent radiodiagnostic investigation reveals there is a fracture with no dislocation, the splint can be left in place for some time. If this investigation reveals that, despite considerable loss of function, there is no fracture, the splint can also be left in place for one week or longer, depending on the clinical progress.
The plaster splint is also suitable for treatment of stress injuries such as tendonitis (golfer or tennis elbow) and severe inflammation (acute rheumatoid arthritis, jaundice, other forms of arthritis).
Situations may arise where a circumferential plaster cast is contraindicated, for example in the case of a combined injury such as one caused by the spokes of a bicycle wheel: deep abrasions and a greenstick fracture. In these situations, a removable gutter splint needs to be used to permit wound care. As well as providing maximum immobilising comfort, the use of a plaster splint prevents vascular congestion and nerve damage upon further post-traumatic swelling. After resorption of the swelling, usually within 3 to 7 days, a circumferential plaster cast or tape bandage can be applied, if indicated.
In other cases, the plaster splint can be left in place a while longer. If the injury involves the lower leg, the ankle or the foot, the leg should be elevated just above the height of the pelvis for 24 to 48 hours. If the injury is to the forearm, wrist or hand, the arm should be supported in an elevated sling or collar’n’cuff, with the wrist higher than the elbow.
Circumferential Plaster Cast
In terms of practical use, it is important to distinguish between an arm cast and a lower leg cast.
The indications for a circumferential plaster cast for the arm are:
- Replacement of a plaster splint (after swelling subsides, usually 1 week) for a fracture with no dislocation.
- Replacement of a plaster splint (after swelling subsides, usually 1 week) for a severe wrist sprain.
- Replacement of a circumferential plaster cast that has broken or become loose.
- De Quervain’s syndrome (short plaster cast with immobilisation of the thumb).
- Dislocated fracture in the wrist or forearm following repositioning.
The indications for a circumferential plaster cast for the lower leg (weight-bearing cast) are:
- Fractures, without shifting, of the metatarsal bone or the first toe.
- For malleolus fractures, the first cast that is applied is one which is non-weight bearing; walking is permitted with crutches. This is followed by a short-leg, weight-bearing cast for a few more weeks.
- Fractures involving toes II through to V can be treated by buddy splinting, in which the injured toe is taped to an adjacent toe, or a rigid support is placed under the sole of the shoe at the site of the MCP joints.
- For conditions involving the Achilles tendon (tendonitis or traumatic injury), replacement of a plaster splint with a grade 2 or 3 ankle sprain (refer to “Support bandaging”).
Follow-up for a Circumferential Plaster Cast
In the case of a fracture involving the wrist or carpal bones, a circumferential forearm plaster cast is applied for four weeks following any necessary repositioning. After one week, an x-ray should be taken to evaluate the position. After four weeks, an x-ray should be taken after removal of the cast to assess callus formation. If this is deemed sufficient, the arm can be remobilised. If there is insufficient callus formation, a new plaster cast should be applied for another 2 to 3 weeks, after which the radiographic assessment should be repeated.
In the case of a forearm fracture, a circumferential upper arm plaster cast, i.e. including the elbow, will be applied following any necessary repositioning. For the first two weeks, weekly radiographic monitoring is necessary to check that the position has remained acceptable. After four to six weeks, an x-ray should be taken after removal of the cast, to assess callus formation. If this is adequate, the arm can be mobilised again. If not, a new forearm cast should be applied for two to four weeks. In children aged 4 years or below, the immobilisation period may be slightly shorter.
In the case of an ankle fracture, a circumferential non-walking plaster cast will be applied for four weeks. Walking is permitted with crutches. After four weeks, callus formation should be assessed by x-ray. If there is sufficient callus formation, a small heel can be applied to the bottom of the plaster cast for a period of two weeks, allowing weight to be put on the leg. For non-dislocated fractures of the mid-foot and the tarsus, a walking plaster cast can be applied immediately for four weeks once the swelling has subsided. Once sufficient callus has formed, use of function can be resumed with or without support bandaging.
Material
- Plaster of Paris and plaster of Paris-resin bandage rolls (6, 8, 10, 12 and 15 cm wide). Plaster of Paris bandages seem to be the most suitable for use in a general practice setting.
- Stockinette (4, 6, 12 and 20 cm wide).
- Synthetic wadding (6, 10 or 15 cm wide). If using flattened cotton wool, a padding bandage should be used to properly fix the cotton wool.
- Absorbent bandage roll. This is used to fix the plaster cast, particularly if a splint is being used. It is advisable to make this bandage wet before use to allow pre-shrinkage. If used in this way, there is a lower risk of the bandage being too tight. This will also make the bandage easier to handle.
- Cambric roller bandage or crepe roller bandage. This can be used to finish the splinting, if necessary.
- Bandage scissors.
- Adhesive plasters.
- Sling or collar’n’cuff.
- Walking heel or plaster cast shoe, available in different sizes
- Tools required to remove the plaster cast are discussed in the section “Instruments”.
How to Apply a Plaster Splint
The following points are important to note:
- Try to achieve maximum immobilisation and comfort using a minimum of material.
- The more plaster of Paris used, the heavier the cast will be and the more difficult removal will be. The aesthetic aspect is also important.
- When using resin or synthetic compounds, gloves should be worn to protect the skin.
- The descriptions for the techniques assume the use of (synthetic resin) plaster bandage.