The shoulder is a complex joint made up of the head of the humerus and the socket of the scapula. This glenohumeral joint is supported by ligaments and a thick cartilage called the labrum as well as muscles surrounding it called the rotator cuff muscles.
Overhead sports such as throwing, swimming, weightlifting can cause repetitive strain on the soft tissues of the shoulder joint. Football tackling, wrestling, falling from a bicycle, skiing injuries, etc. can cause a sudden wrenching of the glenohumeral joint, tearing off the supporting structures mentioned above.
Traumatic injuries can occur to the bony substance of the shoulder, which causes fractures of the humeral head and the socket of the scapula. The collarbone known as the clavicle, attaches to the sternum as a strut for support. Fractures to the clavicle can disrupt this support of the shoulder to the thorax of the body.
The aging process will cause a searing of the smooth surface of the humeral head and the socket, thus creating arthritis.
Pain will occur with range of motion and use as the rough surfaces rub together. The shoulder can also develop inflammation in the bursa, which is a sac of fluid that is interposed above the rotator cuff and below the clavicle. The sac functions as an airbag to cushion the muscles from the bones above. If the sac of fluid becomes too inflamed or too distended, then the shoulder becomes painful. This is knows as bursitis.
Treatment for shoulder injuries require a thorough examination and appropriate ancillary studies such as x-rays, MRI, EMG and/ir nerve conduction studies. Once the diagnosis is made and a conservative approach would be initiated, consisting of anti-inflammatories and physical therapy. If the symptoms in the shoulder did not respond to these treatments, then it is possible that a cortisone injection or surgical intervention would be necessary. If fractures or disruption of the surface of the bone and/or the socket have occurred and have been displaced, then surgery may be required to re-establish normal anatomy.