Ten Nice-to-Know Facts About the Shoulder
Peterson, James A. Ph.D., FACSM
James A. Peterson, Ph.D., FACSM,is a freelance writer and consultant in sports medicine. From 1990 until 1995, Dr. Peterson was director of sports medicine with StairMaster. Until that time, he was professor of physical education at the United States Military Academy.
Copyright © 2019 by American College of Sports Medicine.
- A CURIOUS DESIGN. The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone), as well as associated muscles, ligaments, and tendons. Unlike many of the other joints in the body that support movement (e.g., the hip, which has a deep socket), the shoulder has no socket. As such, the ball of the arm bone moves against an essentially flat surface on the shoulder blade.
- A BARE CONNECTION. The entire shoulder joint barely has any bony connection to the rest of the skeleton. In fact, the only bony connection is where the shoulder connects to the collarbone via the acromioclavicular joint, which is at the tip of the shoulder, and the sternoclavicular joint, which is at the base of the neck. In essence, the shoulder girdle is designed for very free movement of the arm and shoulder.
- EVEN MORE IMPORTANT. The shoulder is more dependent on muscles than any other joint in the body. Given the relative lack of a bony connection between the shoulder and the rest of the body, the lack of a bony socket, and the numerous directions in which the shoulder can move, the eight muscles that control the stability and movement of the shoulder and the arm play a critical role in the process.
- CAUSE AND EFFECT. Issues with any part of the architecture of the shoulder can cause a person to experience pain in the shoulder. In reality, there are numerous potential causes of shoulder pain. All factors considered, one of the easiest and most effective ways to best understand such pain is to zero in on exactly what part of the shoulder hurts. In that regard, specific areas suggest particular possible causes.
- ALL TOO COMMON. Almost eight million people visit a doctor’s office every year for a shoulder-related problem. More than half of these visits are for problems with the rotator cuff. The rotator cuff is composed of a group of muscles and tendons that act as a common stabilizer for the bones of the shoulder. The rotator cuff muscles enable an individual to lift their arm and reach overhead. If they pull an object too fast, rotate objects at awkward angles, or simply overuse their rotator cuff, they can injure it.
- MOST FLEXIBLE. The shoulder is the most mobile joint in the body. It moves up and down, as well as rotates in and out in all planes. Given that it is more mobile, it is also less stable, which makes it more susceptible to injury. It also means that rehabilitating a shoulder injury can be somewhat challenging, because the attendant motion must be restored to have a properly functioning shoulder without experiencing pain.
- THE CATALYST FOR PAIN. Shoulder pain is a common issue in the United States. In fact, according to some estimates, as many as 67% of individuals experience discomfort in their shoulder over the course of their lives. As such, there are a number of factors that might be the underlying cause of shoulder pain, including tendonitis (the most common reason), frozen shoulder, rotator cuff tears, bursitis, osteoarthritis, and dislocation/subluxation.
- A BETTER OPTION. A number of people erroneously believe that they need surgery to fix their shoulder pain/injury. As a rule, they don’t. Rather, they should engage in a plan of action of conservative treatment, including rest, ice, anti-inflammatory drugs, and a gradual return to activity, as well as a well-designed program of stretching and strengthening exercises, which can improve function and decrease pain in the affected area.
- THE REALITY OF AGING. As individuals age, their likelihood of developing osteoarthritis of the shoulder significantly increases. In fact, osteoarthritis, which is a degenerative condition that affects the smooth cartilage on the end of a bone, is the most frequent cause of disability in the United States. It is not considered as a normal part of the aging process. It can, however, be quite debilitating and impact a person’s ability to perform routine activities of daily living, including the ability to sleep.
- BY THE NUMBERS. The impact of shoulder pain entails a substantial socioeconomic burden in the United States, given the attendant health care costs and the loss of workplace productivity. Not only are 25 of 1,000 visits to family physicians related to shoulder pain, but the condition also is responsible for 13% of the sick leaves taken annually in America.