A sling is a medical device made from cloth or webbing which is designed to help a patient keep an injured body part immobile. Typically, a sling is used to support a broken or sprained arm, and consists of a loop to go around the neck and a wide swath of cloth to hold the arm in. If a patient is advised to use a sling, his or her doctor will decide when the sling can be removed. Many patients find slings useful, especially since the immobilization of an injured limb can greatly reduce pain.

The most common instance in which a sling is used is after orthopedic surgery, or before a surgery has been undertaken on a broken bone. On occasion, a doctor will set a broken wrist, for example, in a temporary soft cast, with the intention of operating on it within a short period of time. By wearing a sling, the patient prevents further injury to the area, and reduces the amount of movement, which will in turn reduce the amount of pain felt.

In post surgical applications, a sling helps promote healing. While immobilized, the limb cannot strain stitches or pins which may be an important part of the healing process. In addition, it gives tendons a chance to heal if they have been torn or stretched too far. In extreme cases of orthopedic surgery which require that a patient be held in traction, a sling is frequently used on the legs to lift them up.

A sling may also be used by amputees or people with birth defects, to keep the impacted limb out of the way. Especially when learning how to use a prosthetic device, the muscles of the limb are often heavily strained. A sling allows the limb to rest when it is not in use, so that the patient can slowly develop skills with a prosthesis and the muscles to control it with.

The downside to a sling is that prolonged use is more likely to lead to muscle atrophy. After a sling is removed, a patient may be referred to a physical therapist to regain his or her full range of motion. In physical therapy, the tendons and muscles will be slowly stretched and lengthened so that the limb can be fully extended and contracted. In addition, exercises with light weights will be undertaken to build up the musculature so that it is even with the other side of the body.