Back slabs are commonly used as a first-line treatment when the fracture is swelling or following a surgical procedure.

A back slab consists of plaster (usually plaster of Paris), wool and bandages. The plaster will set in 3 minutes but can take 48 hours to completely dry, it will feel cold and damp. The elevation of your limb is important when following a surgical procedure or injury.

Following a period of elevation, your back slab may begin to feel loose, a bandage can be wrapped over the top of your cast to make it secure.

Back slabs available

Below Knee, Below Elbow and Above Elbow

For every back slab

  • Keep your cast clean and dry

  • Arm: Making a fist and stretching fingers out will also help relieve swelling. It is very important to keep the joints, not in the cast moving. If struggling to make a fist, the opposite hand can be used to help fingers flex and extend.

  • Leg: It's important to keep your toes and knees moving. Clench your toes and open them for 10 minutes every hour – this will help keep the muscles active and help the circulation.

  • Leg: When you are either laying down or sitting, rest your leg on a cushion or pillow with your heel higher than your hip and your knee.

  • In order to alleviate swelling/symptoms of swelling, the arm must be elevated with the hand above the ear whilst making a full fist and releasing fingers for up to five minutes each hour.

For every back slab

  • Don't remove your cast

  • Do not put plastic bags around the cast, these are not waterproof and can cause skin issues under the cast

  • Never attempt to trim your cast


Further information regarding the care of your cast can be found here


For further information please contact the plaster room.

Cheltenham General Hospital

Tel: 0300 422 3148

Gloucestershire Royal Hospital

Tel: 0300 422 8411

Monday to Friday from 8:30am to 4:30pm