The joint is supported by ligaments. These ligaments can get stretched or torn with a dislocation. Sometimes a dislocation can break a piece of your bone. Treatment depends on the severity of damage, and can range from splinting, special exercises, or surgery. It is very common to have swelling in the joint for many months after a dislocation.
This was an open dislocation--the bone had torn open his skin!
The top of his bone, or the joint, is seen to the right. The rope-like structure on the left is his tendon. It had gotten stuck behind the bone so the joint could not be pushed back into position until the tendon was moved over with surgery.