Arthritis can be a factor in causing a rotator cuff tear, and conversely, a long-standing rotator cuff tear can cause a severe form of arthritis. The relationship between the two conditions in the shoulder is complex and circular, where one condition can lead to the other. Shoulder arthritis, particularly the “wear-and-tear” type known as osteoarthritis, involves the breakdown of the smooth cartilage lining the glenohumeral joint. The rotator cuff is a group of four tendons and their muscles that surround this joint, providing stability and allowing the arm to rotate and lift. When arthritis is present, it directly changes the mechanical environment of these tendons, placing them under abnormal stress that can lead to degeneration and tearing.
The Mechanical Link Between Arthritis and Tendon Failure
Chronic inflammation from shoulder arthritis, known as synovitis, contributes to the weakening of the rotator cuff tendons. This inflammation releases enzymes that can degrade the collagen structure within the tendons, causing them to become brittle and more susceptible to tearing over time. The tendons become biologically compromised, often leading to a degenerative tear.
Osteoarthritis can also mechanically interfere with the tendons’ movement. As the cartilage wears away, the underlying bone attempts to repair itself by forming bony growths called osteophytes, or bone spurs. These irregular growths change the space through which the rotator cuff tendons must glide, causing friction and direct wear. The loss of the joint’s smooth surface alters the shoulder’s normal biomechanics, forcing the tendons to work harder and in an unnatural path, which accelerates their failure.
This chronic friction and abnormal loading place the tendons under mechanical overload, increasing the likelihood of a tear, especially in the supraspinatus tendon, the most commonly affected. The combination of structural changes, such as osteophyte formation, and the generalized inflammatory environment creates a hostile joint space. This environment predisposes the already vulnerable tendons to fraying and eventual full-thickness tears.
Rotator Cuff Tear Arthropathy
A distinct and severe condition, known as rotator cuff tear arthropathy, illustrates the opposite direction of this cause-and-effect relationship. This specific form of arthritis develops when a massive, long-standing rotator cuff tear is left untreated. The primary job of the rotator cuff is to keep the head of the humerus, or the “ball” of the joint, centered within the shallow glenoid “socket” during arm movement.
When the tendons are significantly torn and non-functional, they lose the ability to stabilize the joint. This failure allows the unopposed action of the powerful deltoid muscle to pull the humeral head upward, a process called superior migration. The humeral head then rubs directly against the undersurface of the acromion, which is the bony roof of the shoulder.
This abnormal grinding and contact rapidly destroys the remaining articular cartilage, leading to a unique pattern of advanced degenerative arthritis. The condition is characterized by a distinctive lack of large osteophytes, which are common in typical osteoarthritis, and the severe superior displacement of the humeral head. Rotator cuff tear arthropathy results in a rapidly deteriorating joint with significant pain and loss of function, creating a vicious cycle of instability and destruction.
Recognizing the Signs of Combined Shoulder Damage
When a patient has both significant arthritis and a rotator cuff tear, the symptoms are typically more severe and debilitating than either condition alone. A person will often experience persistent, deep-seated pain that is not relieved by rest and frequently worsens at night, interfering with sleep. The pain is often accompanied by a noticeable weakness in the arm, particularly when trying to lift it overhead or away from the body.
A common sign of combined damage is crepitus, a grating, clicking, or grinding sensation felt or heard when the shoulder moves. This noise is caused by the rough, damaged cartilage surfaces of the arthritic joint rubbing together and the displaced humeral head grinding against the acromion. The patient also exhibits a severely restricted active range of motion, meaning they cannot lift the arm themselves. This loss of active movement, sometimes called pseudoparalysis, is a direct result of the non-functioning rotator cuff.
Treatment Options for Arthritis-Associated Tears
Treating the combination of shoulder arthritis and a rotator cuff tear presents a complex challenge because standard treatments for one condition are often ineffective for the other. Initial management typically involves non-surgical approaches to manage pain and inflammation, such as non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroid injections. Physical therapy is also utilized to maintain the remaining range of motion and strengthen the surrounding muscles, though it cannot repair the underlying structural damage.
For advanced cases, especially those with rotator cuff tear arthropathy, surgical intervention is often necessary. Traditional total shoulder replacement, which mimics the shoulder’s normal anatomy, is usually not an option because the irreparable rotator cuff tendons cannot power the new joint. Instead, a specialized procedure called Reverse Total Shoulder Arthroplasty (RTSA) is employed.
The reverse shoulder replacement fundamentally changes the shoulder’s biomechanics by reversing the ball and socket components. The socket is placed where the ball used to be, and a new ball is fixed to the shoulder blade. This design allows the large, healthy deltoid muscle to take over the function of the failed rotator cuff, providing the necessary leverage to lift the arm. RTSA is highly effective at relieving pain and restoring functional arm elevation for patients with this debilitating combination.