Wilderness Medical Series — Module 11

Applying Slings and Splints for Upper Extremity Injuries in the Field

How to apply slings and splints for upper extremity injuries in the field — shoulder sling and swath, humeral shaft splint, and forearm/wrist techniques.

By Joshua Enyart · Founder & Head Instructor, Gray Bearded Green Beret

Former Army Ranger, Green Beret, and full-time survival instructor · three decades of professional instructor experience

Upper extremity injuries — shoulder, upper arm, forearm, and wrist — are extremely common in the backcountry. Falls with an outstretched hand, pack-related shoulder strain, tool accidents, and impact trauma during scrambling all produce injuries that require field management.

Upper extremity injuries differ from lower extremity injuries in their survival implications. They rarely eliminate mobility in the way an ankle or knee injury does. But they are painful, they compromise function, and — in the case of humeral fractures — they can involve a significant blood loss component and nerve injury risk that makes correct field management important.

This article covers three upper extremity splinting techniques: the Sling and Swath for shoulder immobilization, the Humeral Shaft Splint for upper arm fractures, and the Forearm and Wrist Splint for wrist injuries.

Upper Extremity Injuries in the Backcountry: What to Expect

The most common upper extremity injuries in wilderness settings come from two mechanisms: falls and overuse.

Falls onto an outstretched hand (FOOSH) produce a predictable pattern of injury working up the arm. The wrist absorbs the first impact. If the force is great enough to transfer past the wrist, the forearm takes it. If the forearm absorbs without fracturing, the force continues to the shoulder. Colles fractures (distal radius/wrist fractures), radial fractures, and shoulder dislocations or clavicle fractures all result from this mechanism.

Pack-related injuries are a separate mechanism. Shoulder straps that are too thin, too long, or improperly fitted place sustained load on the shoulder girdle and can contribute to bursitis, rotator cuff injury, and in severe cases, brachial plexus compression.

Regardless of mechanism, the field management principles are the same: stabilize the injury in a position of function, protect it from further harm, and manage pain by immobilization.

Fracture Assessment for Upper Extremities

Upper extremity fracture signs and symptoms follow the same pattern as lower extremity fractures:

• Focal pain and tenderness over a specific bony site, rather than diffuse joint pain.
• Rapid swelling and bruising developing at the injury site.
• Loss of normal function: inability to grip, rotate the forearm, or move the shoulder through its normal range without severe pain.
• Crepitus: grating, popping, or grinding sensation at the fracture site.
• Deformity: visible angulation or abnormal positioning of the arm that was not present before the injury.

For humeral fractures specifically, check for radial nerve involvement. The radial nerve runs in close proximity to the humeral shaft. A fracture that displaces or compresses the nerve may produce wrist drop — the inability to extend the wrist — along with numbness on the dorsal (top) surface of the hand. Radial nerve involvement is a signal to handle the humeral fracture with particular care and to document the finding clearly for the receiving medical team.

The Sling and Swath: Shoulder and Upper Arm Immobilization

The sling and swath is the primary immobilization technique for shoulder injuries — dislocations, clavicle fractures, AC joint separations, and rotator cuff injuries significant enough to require support. It can also be applied to humeral fractures after the humeral shaft splint is in place, to provide additional stability.

The technique uses two cravats — triangular bandages. One forms the sling (supports the forearm); the other forms the swath (binds the arm to the body to limit shoulder motion).

Sling and swath procedure:

• Fold the first cravat into a triangle with the point at the elbow side. Tie an overhand knot into one corner of the base to create a pocket. This pocket captures the elbow — the elbow sits in the pocket with the rest of the forearm extending toward the opposite shoulder.
• Place the other two tails of the cravat over the injured shoulder and around the back of the neck. Tie them together to secure the sling. The forearm should be supported at a roughly 90-degree angle to the upper arm, with the wrist slightly elevated compared to the elbow.
• Fold the second cravat into a long rectangular shape — fold it lengthwise until it is four to five inches wide.
• Wrap this cravat around the torso, capturing the upper arm and the sling. Tie it to secure. This is the swath — it prevents the arm from swinging away from the body and limits shoulder girdle motion.

Check sensation in the hand and wrist after application. A sling that compresses the axilla can cause nerve symptoms. If the patient reports new numbness, adjust the swath tension.

The Humeral Shaft Splint

The humerus is the long bone of the upper arm. Fractures of the humeral shaft are painful, may involve the radial nerve, and benefit from splinting to reduce motion at the fracture site and improve comfort during evacuation.

The SAM® splint humeral shaft technique uses the aluminum core folded to create a J-shape that cups the elbow, with the rest of the splint running up the outer surface of the upper arm.

Humeral shaft splint procedure:

• Fold the SAM® splint into thirds.
• Take the bottom two sections and fold a J-shape into them. The curve of the J will cup and capture the elbow. Use the uninjured arm to model the shape before applying it to the injured arm.
• Form a C-curve into the upper section of the splint to add rigidity along the length.
• Mold the upper portion of the splint to the contour of the upper arm.
• Place the elbow in the J-shaped cup. If the splint has excess material extending above the shoulder, fold it down.
• Secure with an elastic bandage from the elbow end upward to the shoulder. The wrap should be firm but not tight enough to restrict circulation.
• Apply a sling and swath over the humeral shaft splint to provide additional support and limit motion.

Check sensation in the hand and ability to extend the wrist (radial nerve function) before and after application.

The Forearm and Wrist Splint

Wrist fractures — most commonly Colles fractures of the distal radius — are among the most common wilderness injuries. The forearm and wrist splint immobilizes the wrist by capturing the hand and running up the forearm.

The position of function for the wrist is slight extension — as though you are about to push a door open. This is the neutral anatomical position that allows the tendons and ligaments of the wrist to remain at their most comfortable tension.

Forearm and wrist splint procedure:

• Fold the SAM® splint so that one end can be rolled into a cylindrical grip that the patient holds in the palm. The roll creates the slight wrist extension needed for position of function. Use the patient's uninjured hand to model the grip size.
• Mold the rest of the splint up and along the volar (palm-side) forearm.
• Secure with an elastic bandage from the wrist end upward toward the elbow. The wrap holds the splint in position — it is not intended to provide additional compression on the wrist joint itself.
• Check grip strength and sensation in the fingers. Any numbness or weakness in the thumb and first two fingers may indicate median nerve involvement — document and report at handoff.

Upper Extremity Injuries and Evacuation Planning

Most isolated upper extremity injuries allow self-rescue or modified self-rescue with assistance. The person with a splinted wrist or a slung shoulder can walk. They cannot carry a full pack, cannot use trekking poles effectively, and need support on technical terrain — but they are not immobile.

The exceptions are humeral fractures with radial nerve involvement, any injury with significant vascular compromise, and bilateral upper extremity injuries that eliminate the ability to grip or support weight. These require more deliberate evacuation planning and urgent signaling.

For all upper extremity injuries, manage pain through immobilization, monitor CMS every thirty minutes, and make evacuation the priority once the splint is in place. An upper extremity injury that is properly splinted and monitored is manageable. An improperly splinted upper extremity injury allowed to move freely during evacuation can convert a fracture into a nerve injury.

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