Casting & Splinting

Casting and splinting is a non-surgical treatment that holds a broken bone or injured joint in the correct position so that it can heal properly.

When a bone breaks or a joint is badly sprained, the pieces or structures need to stay still and properly aligned so the body can repair them. A cast is a rigid shell — usually made from plaster or fibreglass — that completely surrounds the injured area and keeps it from moving. A splint is a partial shell that leaves one side open; it is often used in the first days after an injury when swelling is still increasing, because the open side allows the limb to expand without cutting off circulation. Both devices work by immobilising (keeping still) the injured area so that new bone or tissue can form safely.

Casting and splinting is used whenever an injured bone or joint needs to be held still to heal correctly. It is one of the most common treatments in orthopaedic (bone and joint) and trauma care.

• Fractures (broken bones) of the arm, forearm, wrist, hand, leg, ankle, or foot that do not require surgery
• Fractures that have been surgically corrected and need extra protection during recovery
• Severe sprains or ligament tears — particularly around the ankle or wrist — where joint stability is needed
• Dislocations (when a joint is forced out of its normal position) after the joint has been put back in place
• Tendon injuries that need the affected area kept still during healing
• Stress fractures (tiny cracks caused by repeated force) in athletes or active individuals
• Buckle fractures or greenstick fractures in children, where the bone is only partially broken

Casting or splinting is generally not suitable in certain situations. Your doctor will assess whether another approach is needed.

• Open fractures (where the broken bone has pierced through the skin) — these usually require surgery first
• Fractures with severe misalignment that cannot be corrected without an operation
• Injuries with significant damage to blood vessels or nerves that need immediate surgical repair
• Active skin infections or open wounds directly under where the cast would sit
• Severe swelling or circulatory problems that make a rigid cast unsafe from the start

Casting and splinting is generally very safe, but like any treatment that keeps a limb still for a period of time, it carries some recognised risks.

• Pressure sores or skin irritation under the cast, especially if the padding shifts or the cast becomes too tight
• Swelling after application that makes the cast feel uncomfortably tight, or rarely, dangerously tight (compartment syndrome — a build-up of pressure inside the limb that cuts off blood flow and requires urgent treatment)
• Skin itching, rash, or allergic reaction to the casting material or padding
• Muscle weakness and joint stiffness from the limb being kept still for several weeks
• Joint contracture (a shortening of muscles or tendons that limits movement) if immobilisation is prolonged
• Cast becoming wet, cracked, or loose, which can allow the bone to move out of position
• Deep vein thrombosis or DVT (a blood clot forming in a leg vein) when a lower limb is immobilised for a long time — more common with leg casts
• In children, very rarely, growth disturbance if a fracture involves the growth plate (the area at the end of a growing bone)
• Malunion (the bone heals in a slightly incorrect position) if the cast loosens without being noticed

Because casting and splinting is usually applied after an acute (sudden) injury, formal preparation is often minimal. However, your care team will take several steps before and during the procedure to make sure the bone is correctly positioned and the cast fits safely.

Before the cast or splint is applied, the doctor will usually order one or more of the following assessments.

• X-ray of the injured area to confirm the exact location and type of fracture and to check the alignment of the bone
• Neurovascular check — the doctor or nurse tests the circulation, sensation (feeling), and movement of the fingers or toes beyond the injury to make sure there is no nerve or blood vessel damage
• Assessment of the skin around the injury for any open wounds, blisters, or bruising that could affect where the cast sits
• In complex fractures, a CT scan (a detailed cross-section X-ray) may be requested to see the full picture before deciding on treatment

If a bone is out of alignment, the doctor will perform a reduction (a manoeuvre to move the bone back into the correct position) before applying the cast. This may be done under local anaesthesia (numbing medication injected near the injury), sedation (a relaxing medication given through a drip), or in some cases a brief general anaesthetic (medication that makes the patient fully unconscious). The patient will be asked not to eat or drink for a period of time beforehand if sedation or general anaesthesia is planned — the care team will advise on the exact timeframe.

The procedure itself follows a consistent sequence of steps, though the exact number and details may vary by the body part involved and the type of cast used.

• 1. The injured limb is gently cleaned and any open wounds or abrasions are dressed.
• 2. A stockinette (a soft tubular sleeve) is pulled over the limb to protect the skin.
• 3. Soft cotton or synthetic padding is wrapped around the limb to cushion pressure points and protect bony areas.
• 4. The casting material — wet plaster bandages or fibreglass tape — is wrapped in overlapping layers over the padding.
• 5. The limb is held in the position the doctor has chosen until the material sets firm. Plaster usually sets within minutes but continues to harden over the next day or two; fibreglass hardens faster.
• 6. The edges of the cast are trimmed or padded to prevent them from digging into the skin.
• 7. A final X-ray is usually taken to confirm the bone remains in the correct position inside the cast.
• 8. The care team checks circulation, sensation, and movement of the fingers or toes once more before the patient leaves.

Most patients go home the same day with clear instructions on what to watch for. The recovery period varies considerably depending on which bone was broken, how severe the fracture was, and the patient's age and overall health — your doctor will give a more specific timeframe.

• Elevation: keeping the casted limb raised above heart level — usually for at least the first 24 to 48 hours — helps reduce swelling and discomfort.
• Weight-bearing restrictions: for leg or foot casts, the doctor will specify whether the patient can put any weight through the limb; crutches or a walking frame are often needed.
• Keeping the cast dry: plaster casts must not get wet, as moisture weakens them and causes skin problems. Fibreglass casts may tolerate limited moisture in some situations — the care team will advise. Waterproof covers are available in most pharmacies.
• Checking circulation: the patient or a family member should regularly watch for signs that the cast has become too tight — increasing pain, numbness or tingling in the fingers or toes, the fingers or toes turning pale or bluish, or the limb feeling cold. These signs need urgent medical attention.
• Do not push objects under the cast to scratch itching skin, as this can cause wounds or infections.
• Skin and wound care: once the cast is removed, the skin underneath is often dry and may be scaly; gentle washing and moisturising is usually all that is needed.
• Follow-up X-rays: in most cases the doctor will schedule one or more check-up appointments with repeat X-rays to confirm the bone is healing in the correct position and to decide when the cast can safely come off.
• Cast removal: the cast is cut off by a technician or nurse using a special vibrating saw designed to cut the hard shell without harming the skin. The process is not painful, though the saw is noisy.
• Physiotherapy (exercises to restore movement and strength) is often recommended after the cast is removed, especially for fractures near a joint or for casts worn for several weeks.
• Smoking slows bone healing significantly; patients who smoke are usually advised by their doctor to cut down or stop during the healing period.
• Alcohol can interact with some pain medications and may impair judgement about pain levels — the care team will advise on what is safe.