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This page describes products and general use; it is not medical advice.
A boxer fracture splint is the common name for an ulnar gutter splint: a molded support that runs along the outer (pinky) side of the hand and forearm and holds the ring and little fingers still. This page explains what it is made of, which parts and sizes are named in clinical references, and how it differs from other hand and wrist splints. It is for clinic staff, buyers and students who need to know what the product is.
What a boxer fracture splint is
“Boxer’s fracture” is the name for a break at the end of the fifth metacarpal, the hand bone behind the little finger. The American Academy of Family Physicians (AAFP) describes it as the most common injury for which an ulnar gutter splint or cast is used. The splint named after it is simply an ulnar gutter splint: “ulnar” refers to the pinky side of the forearm, “gutter” to the trough shape of the molded material.
Who uses it: emergency and primary-care clinicians, orthopedic and urgent-care teams, and the staff who stock the supplies for them.
How it is built
A conventional ulnar gutter splint is a layered assembly rather than a single molded part. The Merck Manual describes these components:
- Stockinette: a tubular knit liner running from the knuckle joints (metacarpophalangeal, or MCP, joints) to the middle of the forearm.
- Roll padding: cushioning layered over the stockinette, with extra padding between the fourth and fifth fingers.
- Splinting material: plaster or fiberglass, which sets by an exothermic (heat-releasing) reaction with water.
- Elastic bandage: holds the strip against the padding.
Once set, the strip runs from the fifth finger (distal interphalangeal joint) along the ulnar side of the hand to the middle of the forearm, just short of the elbow. The thumb, index and middle fingers are left free. The AAFP describes the same overall shape.
Splint types for the wrist and hand
The ulnar gutter splint is one of several upper-limb configurations. The AAFP’s splinting reference tabulates ulnar gutter, radial gutter and thumb spica splints and casts side by side, and the same family includes volar and sugar tong forms. They differ mainly in which side of the limb carries the trough and which digits and joints they hold:
- Ulnar gutter: pinky side; holds the ring and little fingers and the wrist; leaves thumb, index and middle fingers free.
- Radial gutter and thumb spica: thumb-side configurations listed in the same AAFP table.
- Sugar tong: a different wrap-around design; see sugar tong splint materials and sizes.
- Single-finger supports: see finger splint types, which includes gutter styles.
- Wrist supports for nerve compression: see carpal tunnel splints.
For the general definition of the product class, see what a splint is.
Material and size specifications that matter
| Component | Specification | Source |
|---|---|---|
| Roll padding width | 5 cm (2 in) | Merck Manual; AAFP (“2-inch padding is used for the hands”) |
| Plaster or fiberglass splinting material width | 7.5 cm (3 in) | Merck Manual |
| Elastic bandage width | 5 cm (2 in) | Merck Manual; see elastic bandages |
| Layers of splinting material | 8 to 10 layers (single-layer rolls) | Merck Manual |
| Sheets of casting material, average adult upper extremity | 6 to 10 sheets | AAFP |
| Stockinette extent | MCP joints to mid-forearm | Merck Manual |
| Splint extent | Fifth-finger distal joint to mid-forearm, just short of the elbow | Merck Manual |
The layer counts differ slightly between the two sources because they count different things (layers of a folded strip versus sheets of casting material). Neither source gives a fixed product size chart.
Safe use and handling basics
- Heat: plaster and fiberglass set with an exothermic reaction, and Merck lists thermal injury as a complication.
- Pressure and circulation: Merck lists pressure sores, nerve injury (neurapraxia), ischemia and compartment syndrome, the last especially from a tight circumferential wrap. The AAFP adds skin breakdown, infection and dermatitis.
- Prolonged immobilization: the AAFP notes pain, stiffness and muscle atrophy.
Application, positioning and follow-up are decisions for a trained clinician.
FAQ
Is a boxer fracture splint the same as an ulnar gutter splint?
Yes. “Boxer splint” is the informal name for the ulnar gutter configuration, and the AAFP names boxer’s fracture as the most common reason it is used.
Which fingers does it hold?
The ring and little fingers, plus the wrist. The thumb, index and middle fingers are not immobilized (Merck Manual).
What materials is it made from?
Stockinette, roll padding, plaster or fiberglass splinting material and an elastic bandage (Merck Manual).
How is it different from a sugar tong splint?
The ulnar gutter splint sits along one side of the hand and forearm, while the sugar tong wraps the limb in a different configuration. See the sugar tong splint guide.
Sources
Checked 2026-10-30.
- Merck Manual Professional, How to Apply an Ulnar Gutter Splint, checked 2026-10-30.
- American Family Physician 2009;80(5):491, common splinting techniques, American Academy of Family Physicians, checked 2026-10-30.
