My shoulder hurts...is it osteoarthritis?

Osteoarthritis is a very common problem. Most people know someone who is dealing with arthritis of at least one joint. Spine, hips, knees, and hands are the most common places for osteoarthritis to cause symptoms. However, any joint can be affected and a common question I hear when a patient presents with shoulder pain is: Do I have arthritis?

First, a bit of anatomy -- the shoulder is composed of two separate joints:

(1) the acromioclavicular...