If you have shoulder pain or recently just had surgery on your shoulder, you may be referred to physical therapy. Similar to the hip, the shoulder is a complex ball and socket joint. It is made up of your scapula (shoulder blade), clavicle (collar bone) and the humerus (arm bone). The shoulder is an extremely mobile joint, but with this mobility comes a risk of instability. Pain in the shoulder could be caused by poor posture, repeated overhead movements which can cause pinching of the rotator cuff tendon or biceps tendon, or even trauma from a fall or an accident.