Shoulder mobility is essential for most daily tasks. Shoulder conditions that impair range of motion can significantly impact functional abilities, such as showering, getting dressed and driving. Bone spurs -- bony outgrowths -- can develop in the shoulder joint, leading to pain and progressively decreased range of motion.
The shoulder is a ball-and-socket joint formed by the rounded head of the humerus -- the upper arm bone -- and the glenoid fossa, an indentation in the shoulder blade. The acromion, which is another part of the shoulder blade, forms a bony roof over the top of the humerus. The rotator cuff muscles -- supraspinatus, infraspinatus, teres minor and subscapularis -- stabilize the humerus, keeping it in the socket as the arm moves. The supraspinatus tendon travels under the acromion in the subacromial space to attach to the front of the shoulder. Bone spurs diminish the space between the humerus and acromion, leading to pain, inflammation and decreased range of motion.
Shoulder bone spurs are caused by osteoarthritis, a progressive disease that causes breakdown of shoulder cartilage. This smooth tissue provides padding between the shoulder bones, helping them glide smoothly with joint movement. With progressive cartilage loss, the shoulder bones begin to rub against each other during arm movement. Small bone spurs, called osteophytes, develop on the humerus as a result of this bone-on-bone friction. The cause of shoulder osteoarthritis is not always apparent. However, it can develop after trauma to the joint, repeated joint dislocations and chronic tendon damage. Bone spurs are identified with x-rays.
Range of Motion
Bone spurs that develop on the humerus affect shoulder range of motion in all directions. Decreased joint space and tightening of the joint capsule -- connective tissue that surrounds the shoulder joint to keep it stable -- contribute to progressive loss of motion. Abduction -- moving the arm out to the side, away from the body -- is often limited to less that 90 degrees of movement. Similar limitation is seen with shoulder flexion, or lifting the arm in front of the body. As the arm is raised, the joint space decreases and the bones come closer to each other. Range of motion is reduced by pain as the bones rub together. External and internal rotation -- outward and inward turning of the humerus -- are also limited due to pain caused by shoulder bone spurs. Activities such as getting dressed and self-care tasks are difficult with decreased arm rotation.
Conservative treatment methods are typically prescribed first to treat shoulder pain and range of motion limitations caused by bone spurs. Antiinflammatory medications and cortisone shots are used to decrease inflammation and reduce swelling in the joint space. Physical therapy interventions -- such as heat, ultrasound, electrical stimulation, ice and compression -- are also used to decrease pain and inflammation. Range of motion exercises are prescribed to improve shoulder function. Manual stretching is performed by the therapist to improve flexibility of the joint capsule. Surgery may be required to treat bone spurs in the shoulder joint. Arthroscopic debridement is performed using a tiny camera and bone shaver to remove bone spurs and increase space in the shoulder joint. Severe bone spurs and joint damage may require a total shoulder replacement. With this procedure, the ends of the shoulder joint bones are removed and replaced with a permanent prosthetic joint, preventing the development of bone spurs in the future.