Merck Manual

Please confirm that you are a health care professional

honeypot link

How To Apply a Thumb Spica Splint


Miranda Lewis

, MD, University of Washington

Reviewed/Revised Jul 2021 | Modified Sep 2022
Topic Resources

Thumb spica splints are devices applied to immobilize the thumb and adjacent structures.


  • Thumb metacarpal fracture

  • Scaphoid fracture

  • Lunate fracture

  • Thumb ulnar collateral ligament injuries

  • De Quervain's tenosynovitis


  • None



  • Stockinette (one piece to cover the area from MCP joints to mid-forearm and a second piece to cover the thumb from the tip to the base of the metacarpal)

  • Roll padding (eg, cotton roll) 5-cm (2-inch) width

  • Plaster or fiberglass splinting material 7.5-cm (3-inch) width—enough to cover from the DIP joint of the thumb to the mid-forearm

  • Strong scissors and/or shears

  • Elastic bandage 5 cm (2-inch) width

  • Lukewarm water and bucket or other container

  • Nonsterile gloves


  • The patient should be positioned so that the operator has appropriate access to the patient's affected hand.

  • Maintain the thumb in a slightly flexed and abducted position as if holding a narrow cup or the stem of a wine glass.

  • Extend the wrist at 10 to 20°.

  • Unless there is additional injury, the splint should allow unrestricted motion of the 2nd through 4th MCP joints.

Step-by-Step Description of Procedure

  • Wear nonsterile gloves.

  • Apply stockinette to cover the thumb.

  • Cut a hole in the second stockinette to allow for protrusion of the thumb.

  • Apply second stockinette to cover the area from the MCP joints to the mid-forearm

  • Wrap the padding from the MCP joint to the mid-forearm slightly beyond the area to be covered by the splint material; overlap each turn by half the width of the padding and periodically tear the wrapping across its width to decrease the risk of tissue compression

  • Wrap the padding around the thumb.

  • Smooth the padding as necessary. Ensure there are no folds in the padding. Tear away any excess padding to prevent areas of localized pressure on the skin.

  • Lay out a length of splint material matching the distance from just past the DIP joint of the thumb to the mid-forearm.

  • Unroll additional splint material, folding it back and forth along the first length until there are 6 to 8 layers (when using single-layer rolls).

  • Alternatively, if using ready-made splint material, cut a single piece to the above length.

  • Immerse the splinting material in lukewarm water.

  • Squeeze excess water from the splinting material (do not wring out plaster).

  • Apply the splint material around the thumb and radial side of the forearm.

  • Fold the extra stockinette and cotton padding to cover all edges of the splinting material.

  • Wrap the elastic wrap over the splinting material distally to proximally and overlap each revolution by half the width of the elastic wrap.

  • Smooth out the splinting material using your palms rather than your fingertips to conform to the contour of the arm to fill in the interstices in the material.

  • Maintain the thumb in a slightly flexed and abducted position and the hand and wrist in a position as if holding a narrow cup or the stem of a wine glass until the splinting material hardens (see figure Thumb spica splint Thumb spica splint Thumb spica splint ).

  • Check the distal neurovascular status (eg, capillary refill, distal sensation, finger flexion and extension).

How to Apply a Thumb Spica Splint

Thumb spica splint

Thumb spica splint


  • Advise the patient to keep the splint dry.

  • Arrange or recommend appropriate follow-up.

  • Instruct the patient to watch for complications such as worsening pain, paresthesias/numbness, and color change to the fingers.

  • Instruct the patient to seek further care if pain cannot be controlled with oral drugs at home.

Warnings and Common Errors

  • Ensure padding and elastic wraps are not applied too tightly.

  • The base of the thumb is a common site for excess plaster folds in this splint.

  • Additional padding may be needed over the radial styloid.

Tips and Tricks

  • Cutting the splinting material lengthwise along the length of the thumb portion of material (from tip to the MCP joint) can allow for better molding around the thumb.

  • Alternatively, small notches can be cut at the base of the thumb perpendicular to the length of the splint to prevent bunching of the plaster in this area.

  • Warm water makes plaster set more quickly, so if you are unfamiliar with applying splints use cooler water to increase your working time.

  • For larger patients, 3-inch cotton padding may be used for the forearm portion of the wrap.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!