Summarize this article:

A homemade sling may be a good choice for minor arm injuries, but it's not enough to ensure proper healing in the case of serious fractures or dislocations. Allow a doctor to examine the injury, take x-rays, and discuss a treatment plan with you. A doctor's final treatment plan may involve the use of a sling – but your injury might also require a cast or surgery. If you use a homemade sling to set a broken bone or a dislocated limb, your arm might heal poorly. You may experience lasting discomfort, and you may need further medical attention.  Common symptoms of broken arms include: Intense pain Tenderness Swelling Loss of motion or decreased sensation Possible open wound with bone sticking out Difference in appearance relative to the uninjured arm   Common symptoms of dislocated arms (most commonly in the form of a dislocated shoulder) include: Pain in the arm, shoulder, and/or collarbone Deformation (a bump on or near the shoulder) Swelling Bruising When a broken bone sticks through the skin—or a wound forms in which bone is visible following a fracture—this is called an "open fracture" or "compound fracture." These fractures are exceptionally painful, dangerous, and difficult to treat. Be aware that the types of injuries that cause compound fractures can also cause other serious trauma. It is essential that you get yourself prompt, effective medical treatment. Do not try to realign compound fractures without the help of a qualified medical professional. The only exceptions to this rule are rare, special cases: when you will not be able to secure immediate medical treatment, and setting a compound fracture by hand is preferable to the alternative of doing nothing at all. You should only ever attempt to realign broken bones when signs of poor circulation appear. Again: if possible, wait for a doctor to reset your broken bones. The exception is when it appears that a fracture is preventing blood from circulating through the limb. Your limb may not be receiving any blood if the area of the limb past the fracture looks pale or blue, has no pulse, loses sensation, or grows cold. In these cases, the potential loss of the limb outweighs the dangers of having an amateur re-set the bone – or of doing the job yourself. If this is the case, visit How to Realign a Fractured Bone for more information.

Summary:
Seek medical attention for broken bones or dislocations. Head straight to the emergency room if you can see a bone in the wound. Only try to reset a bone if you are at risk of losing a limb.