How To Apply a Thumb Spica Splint

Thumb metacarpal fracture

Scaphoid fracture

Lunate fracture

Thumb ulnar collateral ligament injuries

De Quervain's tenosynovitis

None

Thermal injury (caused by the exothermic reaction between plaster or fiberglass and water)

Compartment syndrome (sometimes caused, in part, by excessive tightness of circumferential wrapping)

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.

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).

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

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 medications at home or if the patient develops paresthesias/numbness and/or color change distal to the splint.

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.

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 and can prevent wrinkles once hardened.

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 and to prevent wrinkles when hardened.

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.