The rotator cuff is a group of 4 muscles that are responsible for stability of the shoulder. Unfortunately, rotator cuff injuries are very common, either from repetitive overuse or from trauma to the shoulder. These injuries can occur at any age, but are more prevalent later in life. We often think of athletes or heavy laborers as being the most commonly affected, but older adults can injure the rotator cuff when they fall or strain their shoulder, such as when walking a dog on a leash and the dog lurches. If left untreated, this injury can cause significant pain and severely hamper your ability to use your arm.