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
- Thermal injury (caused by the exothermic reaction between plaster or fiberglass and water)
- Excessive pressure causing skin sores and/or ischemic injury
- Excessive tightness of circumferential wrapping may contribute to compartment syndrome
- 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).
- Check the distal neurovascular status (eg, capillary refill, distal sensation, finger flexion and extension).
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.