An ulnar gutter splint is a temporary orthopedic device used to immobilize and stabilize the hand and wrist following injury. Healthcare providers apply this splint primarily to stabilize fractures or severe soft tissue damage affecting the little-finger side of the hand and forearm (the ulnar aspect). Since it is non-circumferential, the splint accommodates the swelling that often occurs immediately after injury. Restricting movement reduces pain and provides a secure environment for healing.
Anatomy and Purpose of the Splint
The ulnar gutter splint is designed to cradle injured structures along the ulnar side of the arm. It typically begins at the proximal forearm, just below the elbow, and extends down to the ends of the ring and little fingers. The splint material follows the natural curve of the arm, wrist, and hand.
The splint covers the entire length of the fourth (ring) and fifth (little) metacarpal bones, as well as their corresponding phalanges. This coverage achieves immobilization, which helps maintain the correct alignment of fractured bone fragments and protects damaged ligaments or tendons from further strain. The stability provided is crucial for reducing inflammation and pain in the acute phase.
Common Injuries Requiring Immobilization
This splint is used for injuries involving the two most ulnar-sided digits and their hand bones. The most common indication is a fracture of the fifth metacarpal neck, widely known as a Boxer’s fracture. This injury frequently occurs when a person strikes a hard object with a closed fist.
The splint is also the standard temporary treatment for other fractures of the fourth or fifth metacarpals. It is applied for certain non-displaced fractures of the proximal or middle phalanges of the ring and little fingers. Furthermore, soft tissue injuries, such as severe sprains or ligament damage affecting the ulnar side of the hand and wrist, may require this splint for rest and protection. The goal is to prevent rotational or angular movement that could displace the injury or impede healing before definitive treatment, such as casting, can be applied.
Essential Positioning During Application
The precise positioning of the hand within the ulnar gutter splint is important for long-term function. Healthcare providers must set the hand in the “intrinsic plus” position, designed to prevent stiffness and contractures. The wrist is typically positioned in slight extension, usually between 10 to 20 degrees, to help maintain the functional length of the hand tendons.
The metacarpophalangeal (MCP) joints—the knuckles—of the ring and little fingers are flexed significantly, ideally between 70 and 90 degrees. Maintaining this flexion prevents the collateral ligaments from shortening, a common cause of permanent stiffness. In contrast, the proximal and distal interphalangeal (PIP and DIP) joints are placed in a nearly straight or slightly flexed position, often only 5 to 15 degrees of flexion. This positioning ensures the hand heals in the safest and most functional anatomical alignment possible.
Care and Maintenance Instructions
Once the ulnar gutter splint is applied, patients must follow specific instructions to ensure proper healing and prevent complications.
The most important rule is to keep the splint completely dry; water can weaken the material and cause the underlying padding to break down, leading to skin irritation or infection. Patients should never attempt to remove the splint, even temporarily, unless instructed by a healthcare professional.
Inserting objects, such as pens or rulers, into the splint to scratch an itch must be avoided, as this can break the skin and introduce bacteria. To manage swelling, the hand should be elevated above the level of the heart as often as possible, particularly in the first 48 to 72 hours following the injury.
Patients must monitor the hand for signs of complications, such as increased pain, persistent numbness, excessive tightness, a foul odor, or changes in the color of the exposed fingers. Should any of these signs appear, patients must contact their provider immediately for a re-evaluation.