The shoulder is a ball-and-socket joint. The ball of your upper arm bone fits into a socket in your shoulder blade. If the ball slips out, your shoulder has "dislocated."
You can dislocate a shoulder if you fall on your arm, or get hit hard. It can happen during a road accident. You can dislocate a shoulder playing football or volleyball. Skiers and gymnasts also have a higher risk.
A dislocated shoulder causes pain. You may not be able to move your arm. Your shoulder may swell or bruise. And you may see a bump under your skin where the ball has shifted.
A doctor resets the joint by moving your arm into different positions to put the ball back in place. Medication and an arm splint or a sling may help the shoulder heal. Physical therapy may help. If you have a severe dislocation, or if it happens a lot, you may need surgery. Your healthcare provider can create a care plan that is right for you.