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 joint where the collarbone meets the shoulder bone
(2) the glenohumeral joint where the ball of the humerus articulates with the shoulder blade (scapula). Both joints can be affected by osteoarthritis. It is relatively uncommon for osteoarthritis to develop in the glenohumeral joint without a history of trauma or previous injury. We'll discuss that in a minute. First, let's review the acromioclavicular joint.

Causes of Shoulder Pain Besides Arthritis
The glenohumeral joint is the most mobile joint in the body. As a trade off for being so mobile, however, the glenohumeral joint is also less stable than other joints. One of the most common causes of shoulder pain is rotator cuff tendonitis. Other common causes of shoulder pain include:

• Biceps tendonitis: One of the tendons of the biceps muscle attaches at the top of the glenohumeral joint. This condition will often manifest with pain in the front of the shoulder that is worse with carrying heavy objects.
• A tear in the lining (labrum) of the glenohumeral joint (labral tear): This condition may present with pain that feels more "inside" the shoulder. However, a labral tear can feel very similar to biceps tendonitis, bursitis, rotator cuff tendonitis, and glenohumeral arthritis. For this reason, your doctor needs to perform a comprehensive physical examination and may need imaging studies to help precisely diagnose the cause of shoulder pain.
• Shoulder bursitis : This condition typically is exacerbated with overhead movements such as brushing one's hair. It presents very similarly to rotator cuff tendonitis and the two often occur at the same time.

The acromioclavicular joint is a more common place for osteoarthritis (wear-and-tear arthritis) to affect the shoulder, but glenohumeral osteoarthritis is significantly less common than the other causes listed above. Glenohumeral osteoarthritis usually occurs years after a significant shoulder injury, or pattern of repetitive injuries (such as recurrent shoulder dislocation). Often, the patient will have a history of athletics as a youth or heavy weight-lifting. A history of acromioclavicular injury (such as an acromioclavicular separation caused by trauma) will predispose a person to future osteoarthritis in this joint.

However, acromioclavicular arthritis may develop in anyone. When acromioclavicular osteoarthritis is the cause of shoulder pain, pressing on the joint will typically (but not always) hurt.

In addition to taking a full history and performing a comprehensive physical examination, your doctor can help determine if your shoulder pain is coming from osteoarthritis by taking x-rays of the shoulder joint. Typical x-ray findings of osteoarthritis include decreased joint space and bone spurs.