The shoulder is a rather incredible part of the human anatomy. As the most flexible and mobile joint in the body, the shoulder allows the arm to move in a wide range of directions, which is necessary for performing many of the dexterous tasks needed in daily life. Unfortunately, this extreme flexibility comes at a price, as repetitive use of the shoulder joint can damage it and cause pain over time.
Often thought of as a single joint, the shoulder is actually a ball-and-socket made up of both the glenohumeral and acromioclavicular joints. Forming these shoulder joints are the upper arm bone (humerus), shoulder blade (scapula), and the collarbone (clavicle), as well as a number of associated tendons, ligaments, and muscles. The humerus and scapula are surrounded and connected by the rotator cuff, which is a group of muscles and tendons that keeps the shoulder stable and allows for its wide range of rotation. There is also a fluid-filled sac called the bursa between the rotator cuff and a bony prominence on the top of the scapula (acromion), which provides cushioning during movement.
The shoulder is one of the most common locations in the body to be affected by pain, with as much as 26% of the general population dealing with shoulder pain at any given point in time. Shoulder pain can come about immediately or develop gradually, and the type of condition that’s responsible is related to several factors, including age.
The rotator cuff is commonly involved in many cases of shoulder pain
Injuries involving the rotator cuff are among the most common causes of shoulder pain in people of all age groups. In general, younger individuals with a rotator cuff injury usually have a history of repetitive overhead activities that involve the shoulder, like athletes involved in baseball, tennis, or swimming. On the other hand, older individuals usually show signs of a gradual onset of shoulder pain that is often the result of sustained damage to the rotator cuff that has taken place over time.
There are a number of injuries that are collectively referred to as “rotator cuff disorders” because they all include damage to rotator cuff tendons and share similar features and symptoms. These terms are often used interchangeably, but each one should be understood independently because of its unique characteristics:
- Rotator cuff tendinitis: irritation and swelling of one or more of these tendons
- Rotator cuff tear: a partial or complete tear of one of these tendons
- Shoulder impingement syndrome/subacromial impingement: term used to describe when the tendons become compressed—or “impinged”—as they pass through the narrow space beneath the acromion and the humerus
The most common symptoms of rotator cuff disorders are pain, swelling, tenderness, loss of strength, and impaired flexibility, which can together cause various degrees of disability, especially for athletes. These types of injuries can occur from age-related changes, trauma, or both, and the likelihood depends largely on a patient’s age and activity levels. Older age-especially being older than 40-and regular participation in overhead occupations or sports both increase the risk for damaging the rotator cuff. Shoulder impingement syndrome can be further broken down into the following three stages, which provides a clearer picture of the role that age can play in this process:
- Stage 1: normally affects younger patients under the age of 25; at this stage, the condition can still be reversed with treatment
- Stage 2: affects individuals between ages 25-40 and represents a continuation of the process that began in stage 1, as it grows worse and becomes less reversible
- Stage 3: typically affects people over the age of 40; at this stage, the damage has resulted in either a partial or complete rotator cuff tear
The likelihood of frozen shoulder also increases with age
Another fairly common cause of shoulder pain is a condition called adhesive capsulitis, or frozen shoulder. Frozen shoulder occurs when scar tissue forms within the shoulder capsule, which is made up of strong connective tissue that helps keep the shoulder stable. This causes the shoulder capsule to thicken and tighten around the shoulder joint, which means there is less room to move the shoulder normally, eventually causing it to “freeze”.
Frozen shoulder affects up to 5% of the population, but the reasons it develops are not clearly understood. In general, it’s believed that not moving the shoulder joint normally for a long period of time is one of the leading factors, as most people who get frozen shoulder have kept their shoulder from moving due to a recent injury, surgery, pain, or some other condition. Age also plays a part, as frozen shoulder most commonly affects people between the ages of 40-60, which could be due to sustained damage to the shoulder over time or lack of shoulder movement. Women and individuals with arthritis, diabetes, cardiovascular disease, and other health conditions are also more likely to develop frozen shoulder.
Another common shoulder injury seen in many age groups is called a labral tear. The labrum is a cup-shaped rim of cartilage that lines the inside of the shoulder joint. It is the attachment site for the ligaments and supports the joint along with the rotator cuff tendons and muscles. If the labrum is pushed beyond its limits, either from a single injury or due to repeated damage over time, it can get torn and cause symptoms like pain, a feeling of instability, a catching or locking sensation, and/or a loss of shoulder strength and flexibility. Labral tears are most commonly seen in athletes of sports that involve overhead motions-like baseball pitchers-but older adults are also at an increased risk because the labrum becomes more brittle with age.
When the labrum gets damaged or torn, it puts the shoulder at risk for looseness and dislocation, which can lead to shoulder instability. This condition occurs when the structures of the shoulder joint become stretched, torn, or detached, which allows the ball of the shoulder joint to move either partially or completely out of the socket. Like labral tears, shoulder instability can either be caused by a single, traumatic event or develop gradually over time, and the primary symptom is a persistent feeling that the shoulder is loose or slipping in and out of the joint. People of any age can experience shoulder instability, but young, active patients that dislocate their shoulder are at an increased risk for experiencing regular instability later in life