How to Make a Thumb Spica Splint

A thumb spica splint is a partial cast designed to immobilise the thumb. Commonly used in emergency rooms, the splint combines hard plaster and bandages, which treat injuries like sprains and minor fractures. For severe injuries, it temporarily immobilises the thumb until surgery is performed. After surgery, a thumb spica splint helps in the healing process.

Place the stockinet over the hand and pull it down to the middle of the forearm. Cut openings for the fingers and the thumb. Wrap Webril cotton padding around the thumb, palm and to the middle of the forearm. Apply extra padding around the bony protrusions of the thumb and wrist joints.

Measure plaster sheets. An average-sized adult splint requires 10 plaster sheets, 3-inches wide. Lay the plaster from the tip of the thumb to the middle of the forearm. Cut the top section of the plaster into two stripes using a scissor to allow for easier moulding of the thumb.

Submerge the plaster in a bucket of water. Remove the wet plaster, squeeze out excess water and place on a towel to remove wrinkles and folds.

Apply the wet plaster to the top of the thumb and forearm. Mold the plaster around the thumb, making sure to smooth the edges, so they do not become sharp.

Apply a bandage wrap over the wet plaster, starting at the thumb, wrapping around the hand and finishing at the middle of the forearm. Refrain from wrapping too tightly. Secure the end of the wrap with either bandage tape or clips.

Finish moulding the plaster while it is still wet. During this time, the patient remains still while placing his hand in a position similar to holding a glass. This should be done until the plaster has dried.

Check if the splint is too tight by inspecting the thumb and fingers for any redness or swelling. Ask the patient if he can move his fingers freely without discomfort.


Remove the splint if there are signs of weakness, numbness, severe pain or bluish skin colour. If so, immediately contact a physician.

Things You'll Need

  • Stockinet
  • Webril cotton padding
  • 10 sheets of plaster
  • Scissors
  • Water bucket
  • Towel
  • Bandage wrap
  • Bandage tape
  • Bandage clips
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About the Author

Deborah Lundin is a professional writer with more than 20 years of experience in the medical field and as a small business owner. She studied medical science and sociology at Northern Illinois University. Her passions and interests include fitness, health, healthy eating, children and pets.