Plaster cast

A plaster cast is used to form a rigid splint and protect fractured or broken limbs, restricting movement so that your bones may heal.

The cast is applied using water and plaster-of-paris. The chemical reaction causes the plaster to feel warm, but as the water evaporates it will feel ice cold. It takes two to three days for a cast to dry and set properly. The plaster may feel tight for some time after application. It is important not to put weight on it for at least 48 hours.


  • Do not wet your plaster cast - it will become soggy.
  • Do not stand your plaster cast on a hard surface during the three days it takes to dry, e.g. on the floor.
  • Do not attempt to cut or remove your plaster cast.
  • Do not heat or paint your plaster cast.
  • Do not push anything under your plaster cast, as you may damage the skin and cause infections.
  • Do not pull out the padding under your cast. It is there to prevent chaffing and protect your injury.
  • Do not walk on a cast until your doctor has fitted a rubber heel. Use your crutches.

You should:

  • Move your fingers / toes frequently.
  • Elevate your limb on one or two pillows or in a sling for as long as instructed by your doctor.

Remember, if your fingers or toes become blue or white, as well as cold and swollen, you should:

  • Keep your limb elevated at the level of your heart
  • Move your fingers or toes frequently

When to contact the hospital

Contact the hospital if:

  • The above information does not help and you experience a tingling sensation or numbness in your finger or toes. The plaster cast may be too tight and may need to be split.
  • Your cast cracks, becomes loose or feels uncomfortable.
  • You are unable to move your fingers or toes.
  • There is a recurring burning pain.
  • There is a discharge or offensive smell.
  • You experience intense pain.


  • To ensure that you regain effective use of your limb after the cast is removed, you must keep it elevated, and exercise the joints and muscles as often as possible.

The Arm

  • Move all joints outside your plaster cast, e.g. shoulder, elbow, fingers.
  • Tighten your muscles of your arm inside your plaster cast.
  • Straighten your fingers.
  • Make a fist.

The Leg

  • Move all joints outside your plaster cast, eg hip, knee, ankle, toes.
  • Straighten your knee inside your plaster, to exercise your leg muscles.
  • Move your foot up and down inside your plaster cast, but only after two days when your plaster is dry.
  • Without assistance, lift only your leg in the plaster cast, keeping your knee straight.
  • Do these exercises ten times per hour, every day.

Be Patient

Most casts stay on for up to six weeks, but sometimes injuries require a second cast to be fitted; your doctor will monitor your progress. You will be surprised, how quickly you learn to live with your cast.