Osteoarthritis, also known as "wear and tear" arthritis, occurs when the cartilage that cushions and protects the ends of your bones gradually wears away. This leads to pain and stiffness that worsens over time, making it difficult to do daily activities.| orthoinfo.aaos.org
In a shoulder dislocation, the head of the upper arm bone (humerus) may come either partially or completely out of the socket. To treat a dislocation, your doctor will place the ball of your upper arm bone back into the shoulder socket, a procedure called a "reduction."| orthoinfo.aaos.org
Rheumatoid arthritis is a chronic autoimmune disease that attacks multiple joints throughout the body. Although there is no cure for rheumatoid arthritis, there are a number of treatments that can help relieve joint pain and improve functioning.| orthoinfo.aaos.org
Your arm is kept in your shoulder socket by your rotator cuff. The rotator cuff is a group of four muscles that come together as tendons to form a covering around the shoulder. When one of these tendons is torn, it may be painful to lift or rotate your arm.| orthoinfo.aaos.org