Fundamental Techniques for Splinting Extremity Fractures

4 Ways to Immobilize Broken Bones

Splinting is the way to treat broken bones (also known as fractures) until you can get to a doctor. A splint can be made from scratch out of household items or it can be commercially produced specifically for splinting fractures. In some cases, when a toe or a finger is used, an uninjured neighbor can be the splint.

Splints can also be used for sprains or dislocations (disruptions of joints, such as the shoulder or the knee). Regardless whether you're splinting a fracture or a dislocation and whether you use something designed as a splint or fashion it yourself out of sticks in the forest, the concepts are the same.

Students practicing making medical splint in training class

Caiaimage / Trevor Adeline / Getty Images

Solid as a Rock

The idea of a splint is to minimize motion of damaged bones or joints. When a bone is broken completely, pressure on the broken pieces can cause the jagged bits of bone to move and damage the softer tissues around it. For bones that are cracked, but not completely separated, external pressures on the bone can lead to increased damage and potentially even cause a broken bone to completely come apart.

The injury doesn't have to be a fracture. External pressures can cause already damaged joints to become even more unstable. Regardless of whether the damage is to hard tissue like bone or to complicated soft tissues like those found in a joint, treatment relies on immobilization.

To avoid external pressure from further damaging a broken bone, it is necessary to immobilize—otherwise known as splint—the area. Most fractures occur to extremities (arms and legs), but there are bones all over the body (about 206 altogether). Even when the broken bone is not in an extremity, such as the ribs or the pelvis, it is vital to immobilize it as much as possible to reduce the potential for further injury. Most of the examples used here will be of extremity fractures.

Fundamentals of Splinting

An extremity splint will not work unless you completely encapsulate the injury within the splint. That means you must immobilize joints above and below the fracture. If, for example, an arm is broken in the middle of the forearm, more than just the forearm will need to be splinted. Because a moving wrist or elbow will exert pressure on the bones of the forearm, a break in that area necessitates immobilization of the wrist and the elbow as well. If they can't move, they won't twist and tweak the radius and ulna (bones of the lower arm).

In the case of a dislocation or sprain, not only will the joint need to be immobilized but so will the structures (usually bones) on either side of the joint. In the case of a knee, for example, the thigh (femur) and the lower leg (tibia and fibula) will have to be splinted to keep the knee from moving. Some say dislocations are actually much more painful than fractures, and the patient is likely not to move the extremity without any encouragement at all.

Assess the Function

The reason to splint an injury, especially to an extremity, is not to cure it. In many cases, severe fractures will require significant, even surgical, treatment to repair the damage.

A first aid splint is used to get the patient to the hospital or doctor. Sometimes, a splint may facilitate moving the injured patient, either by making it possible to move the patient without further injury or by making it possible for the patient to move on their own.

While helping to get the patient to a doctor, it's important not to make things worse. First and foremost, splints must not further the injury to the extremity. Proper immobilization usually inhibits additional damage and that can be measured by assessing the function of the extremity. Circulation, sensation, and motion are the hallmarks of function in all extremities.

Be sure to assess the function of an extremity at least twice. Check once before any treatment is applied, and then again after the splinting is done. If any of the functionality (circulation, sensation, and motion) has disappeared or gotten worse, try to adjust—or even remove—the splint. Loss of function is a big deal that can lead to permanent damage if left unchecked.

Assessing Blood Flow

Blood flow to the injured area (circulation) can be interrupted if damage to the surrounding tissues includes blood vessels. Anything strong enough to break a bone is strong enough to disrupt arteries, veins, and capillaries. To assess circulation, feel the extremity and its twin (if the right arm is broken, compare the right arm to the left arm) for warmth. The injured extremity should be as warm as the opposite extremity. If it's cooler, that's a sign that blood flow in the area is compromised.

Compare the color. Purple, blue, splotchy, or pale are all signs of decreased blood flow to the extremity.

If you know how to take a pulse, compare pulses at the ends of the extremities. If the injured extremity's pulse is absent or very weak, it's an indicator of circulatory problems.

The gold standard has always been to use capillary refill (put a little pressure on the fingernails or toenails to "blanch" them or squeeze the color out of them and then let go, the color is supposed to return in less than two seconds), but there is very little evidence that capillary refill is a reliable measurement.

Assessing Sensation

Sensation is the second measurement of function. In this case, the test is simple: "Can you feel that?"

Without letting the patient see what toe or finger you're touching, ask them to tell you which one it is (keep it simple and use pinkies or big toes, as middle toes and fingers aren't always easy for patients to describe). If the patient cannot feel you touching an extremity (or gets confused about what you're touching), it's an indicator that either the extremity doesn't have enough circulation, causing the nerves to malfunction, or that there's actual nerve damage.

Assessing Motion

The last measurement of function is motion. Can the patient move the extremity?

A loss of motion is an indicator of either a loss of circulation, damage to motor nerves, or structural failure. Bones and muscles are just levers and pulleys designed to make things move a certain way. If you break the supporting structure, sometimes the machine doesn't move the way it's supposed to move.

Slings and Swaths

Broken bones in different areas of the body require different techniques to immobilize them. Starting at the top, let's take a look at the different types of splints and where they might be used most effectively.

Injuries to the shoulder girdle (clavicle and scapula) or to the upper arm (humerus) can only be properly treated with a sling and a swath. Lower arm injuries should be splinted with one of the techniques below, but can still be placed in a sling to help manage the injury. It's also easier for the patient to move around if the splinted arm is in a sling.

A sling is basically a hammock for your arm. It provides some support for the weight of the arm rather than letting it dangle and pull on the injured bones and tissues. A swath is used to strap the arm, still in the sling, to the patient's body.

Slings can be commercially produced (typical after surgery) or they can be fashioned out of a triangular bandage or even a long shirttail.

Cardboard Splints

The most economical of all commercial splints is the cardboard splint. A cardboard splint is just as it sounds, a splint made of cardboard and designed for first-aid use. Cardboard splints can also be fashioned out of any sort of thick-walled box. With a piece of cardboard, a roll of tape, a towel, and a pair of scissors, almost any extremity fracture can be splinted.

Cardboard splints can be bulky and difficult to apply, plus they don't work if they get wet. Also, a cardboard splint might make it difficult to see an injured extremity in order to reassess function or to treat open wounds and control bleeding.

Aluminum Splints

Malleable aluminum splints usually come in a roll, but can also come in flat, padded versions. Aluminum splints can be shaped to fit an injured extremity very easily and they hold their shape in the rain. They're more expensive than cardboard, but take up much less room and can be applied more easily and with much less bulk once they're attached.

With practice, aluminum splints can be applied quickly, without hiding as much of the extremity as a cardboard splint. Aluminum splints are also commonly used for finger splints and come in small, ready-made packages.


Ankle injuries can be properly splinted using nothing more than a bed pillow and a roll of tape. A decent pillow (down just doesn't really work for this) can be wrapped around the foot on an injured ankle and taped around the leg. It effectively creates a soft 'boot' to hold an injured ankle.

A wide enough pillow can also be used to splint arm or lower leg injuries, although it's not ideal.

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  • Gray K, Briseno MR, Otsuka NY. The association between capillary refill time and arterial flow in the pediatric upper extremity. J Pediatr Orthop B. 2008;17(5):257-60. doi:10.1097/BPB.0b013e32830b6209