Shoulder Arthritis

The shoulder is one of the most complex joints in your body and allows your arm to rotate and move in many different directions. The shoulder joint is described as a “ball and socket” joint, however, the socket is very shallow and is similar to a golf ball resting on a tee. The shoulder is made up of three bones: the humerus (upper arm bone), the clavicle (collarbone), and the scapula (shoulder blade). The outer portion of the scapula bone is called the glenoid and is the golf tee where the ball of the humeral bone rests to make up the shoulder joint. Articular cartilage covers both ends of the bones in the joint and allows the bones to glide easily as the joint is moved.

Shoulder arthritis occurs when the cartilage becomes worn or damaged, resulting in loss of joint gliding and increased bone on bone contact. X-rays can show narrowing of the joint space, bone spurs, and dense bone around the shoulder joint.

Types of Shoulder Arthritis

Shoulder arthritis can be due to several different factors, including genetics, previous injuries to the shoulder, chronic rotator cuff injury, or from other disease that increase joint inflammation.

• Osteoarthritis is the most common type of shoulder arthritis and is generally due to natural wear of the shoulder over time. The chance of developing osteoarthritis increases with age and is common in patients over 50 years old.

• Post-traumatic arthritis is due to previous injuries to the shoulder that damage the cartilage. Patients with a history of shoulder fracture or with multiple shoulder dislocations can develop this type of arthritis.

• Rotator cuff arthritis/arthropathy is found in patients who have a massive, chronic rotator cuff tear. The loss of rotator cuff muscles for a prolonged period of time leads to overuse of other muscles that cause abnormal wear of the shoulder joint.

• Inflammatory arthritis is due to any condition that leads to joint inflammation. The most common cause is rheumatoid arthritis, but can be due to any autoimmune disease.

Symptoms

Patients with shoulder arthritis generally have pain with movement of the shoulder, with a dull or toothache-like pain at rest. There can be an increase in pain at night as well. Patients may also notice a decrease in range of motion, or the ability to move the arm, which is due to the bone spurs that form around the joint and loss of the joint gliding surface. Clicking or grinding of the joint can also be felt (or heard).

Diagnosis

Shoulder arthritis is diagnosed using physical examination and imaging studies to confirm the diagnosis. The physical examination is used to identify areas of pain, weakness, and changes in range of motion of the shoulder. X-rays help evaluate for the presence of a bone spur or any arthritic changes of the shoulder joint. MRI (magnetic resonance imaging) allows us to evaluate the soft tissue and non-bony parts of your shoulder and specifically look at the cartilage surface of the shoulder joint and the rotator cuff tendons. CT (computed tomography) is used to evaluate the bones of the shoulder joint, in particular, to look for any change to the bony architecture of the shoulder.

Treatment

Treatment of shoulder arthritis can be done with non-surgical or surgical means. The goal of treatment is to reduce pain and regain function of the shoulder. Non-surgical treatment is used first and can be used to manage symptoms for the majority of patients with shoulder arthritis. These therapies are used to reduce inflammation associated with injury and allow you to strengthen the shoulder muscles and regain function. Non-surgical treatment options include:

• Rest

• Change in activities: Avoiding activities that irritate the shoulder, specifically overhead motions

• Non-steroidal anti-inflammatory medications (NSAIDs) can help decrease inflammation

• Injections:

  • Steroid injections can help decrease inflammation in the shoulder joint.

  • Viscosupplementation injections provide a lubricant to the shoulder joint. These injections may not be covered by insurance.

  • Platelet-rich plasma injections (PRP) is currently being studied as another treatment for shoulder arthritis. The current research shows a modest improvement in pain in patients with knee arthritis, but there is no evidence that shows reversal of the arthritis. These injections are not covered by insurance, as they are considered experimental.

There is a group of patients who do not improve with non-surgical treatment and may require surgical treatment. Surgery for shoulder arthritis involves replacing the ball and the socket of the shoulder with a shoulder replacement. There are two different types of shoulder replacement that are used for specific types of arthritis.

• Anatomic shoulder replacement: This surgery replaces the ball and socket of the shoulder joint with a plastic socket and a metal stem that goes into the humerus (upper arm bone) with a metal ball. This type of replacement is used in patients with uninjured rotator cuff tendons and those with minimal change to the bony architecture of the shoulder

• Reverse shoulder replacement: The procedure is designed to replace the arthritic shoulder with metal and plastic implants and allow another large muscle in your shoulder, the deltoid, to move the shoulder joint. The difference with a reverse shoulder replacement, is that the socket of the shoulder is replaced with a metal ball and the ball of the shoulder is replaced with a metal socket. This allows the muscular mechanics of the shoulder to change and move the shoulder without the need for the rotator cuff muscles.