Bone spurs, also known as osteophytes, are outgrowths of bone along bone edges. While common in various joints, they frequently occur in the shoulder, potentially causing pain or discomfort. Their presence often indicates an underlying response to joint conditions.
What Are Shoulder Bone Spurs?
Shoulder bone spurs are new bone tissue that develops in response to joint stress or degeneration. These growths are essentially extra bone produced by the body. In the shoulder, common locations include beneath the acromion (tip of the shoulder blade), and along the edges of the glenoid (shoulder socket) or humerus (upper arm bone). While bone spurs can be smooth and might not always cause symptoms, they can lead to pain and restricted movement if they press or rub against surrounding soft tissues like ligaments, tendons, or nerves.
Key Causes of Shoulder Bone Spurs
Shoulder bone spurs commonly arise from conditions affecting joint integrity and function. Osteoarthritis, a degenerative joint disease, is a frequent cause. As protective cartilage in the shoulder joint wears down, bones may rub together.
Rotator cuff tendinopathy or tears also contribute to spur formation. Chronic inflammation or injury to these tendons can lead to bone growth on the acromion or humerus as the body tries to repair or protect the affected area. Shoulder impingement syndrome, characterized by repetitive compression of soft tissues, can likewise trigger reactive bone growth. Persistent inflammation within the joint, such as from bursitis, can also stimulate bone formation. An acute injury or trauma to the shoulder can sometimes result in bone spur development as part of the body’s healing process.
Factors Increasing Bone Spur Risk
Several factors increase the likelihood of developing shoulder bone spurs by predisposing individuals to their causes. Advancing age is a significant risk factor, as natural wear and tear on joints contributes to degenerative changes. Genetic predisposition also plays a role; individuals with a family history of bone spurs or certain types of arthritis may be more susceptible.
Occupations or activities involving repetitive overhead movements, such as those performed by painters, swimmers, or baseball players, place increased stress on the shoulder joint, raising the risk. Poor posture can also contribute by placing undue stress on shoulder joints, narrowing the space where tendons and bone interact. Obesity can also add to overall joint stress, potentially increasing risk, though less directly than for weight-bearing joints. A history of previous shoulder injuries or surgeries can alter joint mechanics, making the area more vulnerable.
How Bone Spurs Form
Bone spurs are part of the body’s natural healing and protective response to joint stress, injury, or degeneration. When a joint experiences chronic friction, inflammation, or damage, specialized bone-forming cells called osteoblasts become activated. These osteoblasts deposit new bone tissue at the site of stress, particularly at the margins of joints or where tendons and ligaments attach to bone, essentially attempting to stabilize an injured or degenerating joint by adding extra bone. In some cases, bone spurs can also develop as ligaments or tendons calcify where they insert into bone. This process is typically slow and progressive.