Shoulder Arthritis: Overview

Shoulder Arthritis: Overview

Arthritis of the shoulder, also referred to as osteoarthritis, results from a loss of articular cartilage in the joint. Articular cartilage is the smooth connective tissue, which covers the ends of bones and allows for our joints to move easily and pain-free. Cartilage does not have pain receptors, whereas bone does.

This is why over time, as the cartilage wears away, there is now bone contacting bone, which results in pain and stiffness of the joint. Arthritis can affect many joints in the body, and according to the CDC, 1 in 4 Americans are affected by arthritis. Shoulder arthritis accounts for a large portion, with up to 33% of adults age 60 and older being impacted.

The prevalence of shoulder arthritis increases with age, with women being more susceptible than men. Osteoarthritis is the most common form of arthritis and can be classified into two categories. Primary osteoarthritis is caused by normal wear and tear on the joint as patients age.

Secondary osteoarthritis means the wear and tear results from an underlying cause. These include, but are not limited to, autoimmune disorders like rheumatoid arthritis, prior trauma or injuries sustained to the shoulder, osteonecrosis, also known as bone death, or massive rotator cuff tears that have gone untreated.

Although it is not possible to prevent arthritis, there are steps patients can take to lower their risk. Avoiding overuse and high-risk activities results in less stress across the joint. In addition, maintaining a healthy lifestyle, including a well-balanced diet and participating in physical therapy to stretch and strengthen the shoulder, can also help lower a patient's risk.

Looking at the anatomy of the shoulder, the deltoid and pectoralis major muscles can be seen. These large complexes help provide strength and power to the shoulder joint. Underneath these muscles, we find the rotator cuff muscles, including the supraspinatus, infraspinatus, teres minor, and subscapularis.

Collectively, the rotator cuff contributes to stability of the shoulder joint, along with help from the glenohumeral ligaments and joint capsule. There are 3 bones that make up the shoulder, the upper arm bone, known as the humerus, the shoulder blade, known as the scapula, and the collarbone, known as the clavicle.

The scapula has a pear-shaped extension lined with articular cartilage that acts as the socket of the shoulder, called the glenoid. The glenoid socket contacts the rounded portion of the humerus, known as the humoral head, during movement and is also lined with articular cartilage. Together, the humeral head and glenoid are referred to as the glenohumeral joints.

It is the loss of cartilage within this joint that results in shoulder arthritis. Patients with shoulder arthritis may experience symptoms such as pain, which is aggravated by activity, and stiffness, particularly in the morning, that may inhibit their normal shoulder motion.

Common complaints include no longer being able to reach for objects high on a shelf, reaching behind one's back, or difficulty combing one's hair. In addition to pain and stiffness, some patients may also experience symptoms of catching or clicking within their shoulder. These symptoms tend to come on gradually over a long period of time but can also occur rather suddenly.

When a patient sees a health care professional, they will perform a physical examination of the shoulder. The doctor may look at the patient's range of motion, test the strength of the muscles that surround the shoulder joint, evaluate for signs of previous injuries or surgeries, and ensure the patient's nerves around the shoulder are functioning.

A doctor will order x-rays to verify the diagnosis of shoulder osteoarthritis, which allows them to assess the loss of cartilage in the glenohumeral joint. Although cartilage is not visible on an x-ray, doctors can evaluate for its loss by assessing the amount of space in between the humeral head and glenoid. They may also look for other signs such as bone spurs.

In addition to an x-ray, a surgeon may also order an MRI to evaluate for the soft tissue structures of the shoulder, mainly the rotator cuff tendons. After review of the imaging tests and correlation with the patient's symptoms, the doctor will determine and communicate whether nonoperative or surgical management is best for the patient.