Plaster cast for an arm: what to know

A cast can support a fracture or protect an area after a reduction or another injury treatment. For example, a distal radius fracture may need the wrist and forearm held still while the bone settles. Plaster of Paris can be moulded around the limb; fibreglass cast material is another option. The choice depends on swelling, the injury, the required support, and the clinician’s plan. A cast may be changed as swelling falls or healing progresses. It should feel supportive, not painfully tight, and the fingers should remain warm with expected colour and sensation.

Keep the cast dry unless the treating team gives different instructions, and never push objects inside to scratch. Rest the arm elevated above heart level when swelling is present, especially early on. Move the free fingers gently and regularly if allowed, but do not lift, lean, or drive against the instructions you were given. Check the skin at the edges for rubbing and keep follow-up appointments so alignment and fit can be reviewed. After the cast is removed, physiotherapy may help restore wrist, elbow, hand, and shoulder movement and strength.

Seek urgent assessment if fingers become blue, pale, cold, increasingly numb, difficult to move, or much more swollen, or if pain is severe despite elevation and prescribed relief. Contact the cast team for cracks, softening, wetness, foul odour, new rubbing, or a cast that becomes loose or tight. Do not cut, pad, or reshape the cast yourself. Sudden chest symptoms or breathlessness also need emergency care.

How long should I wear this cast, and when is the next check? Which finger and arm movements are safe? How should I manage bathing, sleep, work, and driving? What changes mean the cast is too tight, and when will rehabilitation begin?