The shoulder is the most flexible joint in your body, and given the number of everyday activities it’s involved in—from brushing your hair to reaching up into the cupboard—it’s easy to see why shoulder pain is something you’d want to get to the bottom of right away. Shoulder pain can be due to osteoarthritis, muscle tears, tendonitis, and several other causes. The many possibilities are owed to the anatomy involved in allowing your shoulder to do what it does.
Shoulder pain, also called deltoid pain, is an extremely common problem. Given the shoulder’s complex anatomy, there are many potential causes. To best understand them, it’s easiest to explore the possibilities by zeroing in on exactly what part of the shoulder hurts.
Outside of the Shoulder
The most common cause of pain over the outside of the shoulder is a rotator cuff problem.
Rotator Cuff Problem: Rotator cuff problems are usually painful with activities such as reaching or throwing. In addition, the deep, aching shoulder pain from a rotator cuff problem tends to be worse or flare at night. The reasoning is unclear, but it’s not unusual for patients with rotator cuff tendonitis or a rotator cuff tear to be awakened from sleep or have difficulty falling asleep because of shoulder pain.
In terms of mobility, a limited active range of motion is typical of a rotator cuff problem. Since the injured or inflamed muscle will not do the appropriate work, the shoulder often feels stiff. But if someone does the work for you by lifting your arm, the shoulder moves normally.
Frozen Shoulder: Frozen shoulder is a common condition that leads to stiffness of the joint and sometimes constant pain, or just discomfort when reaching behind your back or head. While any shoulder pain can eventually progress to a frozen shoulder, the most common cause is a rotator cuff tendonitis. Finally, with a frozen shoulder, there is a loss of passive range of motion (what the doctor can do when manipulating the arm), as well as a loss of active range of motion (what the patient can do alone).
Front of the Shoulder
Pain in the front of the shoulder is most commonly related to the biceps tendon—that which attaches deep inside the shoulder. Problems of the biceps include biceps tendonitis, SLAP tears, and biceps tears.
Bicep Tendonitis: People with bicep tendonitis usually develop gradual pain at the front of the shoulder that moves down over the biceps muscle. The pain is often worse with repetitive lifting, carrying heavy bags, or overhead activities. Problems with the biceps tendon may also cause a clicking sound when the shoulder is rotated in an arc, and like rotator cuff problems, the pain may be worse at night.
Bicep Tendon Rupture: More seriously, a bicep tendon rupture may occur, which means that the bicep muscle breaks free near the joint. The symptoms of a bicep tendon rupture include a sudden “pop” along with an acute worsening of pain, as well as bruising, swelling, and often the formation of a lump that forms just above the antecubital fossa (your elbow pit).
SLAP Tears: A superior labrum anterior posterior tear, more commonly referred to as a SLAP tear, is a specific type of glenoid labrum (shoulder joint) tear. The most common cause is a fall on an outstretched hand. It’s also a common tear in athletes who throw overhead (for example, baseball pitchers) or workers involved in repetitive overhead activities. Symptoms may include a deep shoulder pain, a catching sensation, and a popping sound with movement (called crepitus).
Shoulder Osteoarthritis: With shoulder osteoarthritis, a person often describes a deep shoulder pain or a pain at the front of the shoulder, along with stiffness. There is generally a loss of both active and passive range of motion. Shoulder arthritis is relatively uncommon and is usually preceded by an injury to the arm, neck, or shoulder that occurred years prior.
Top of Shoulder
The most common cause of pain in the top of the shoulder is an abnormal acromioclavicular joint (AC) joint. Problems of the AC joint include AC arthritis and AC separation.
AC Arthritis: Shoulder arthritis is less common than knee and hip arthritis, but when severe, may require a joint replacement surgery. It can cause bone spurs and rough cartilage that limits mobility, as well as a wearing away of smooth cartilage. Exposed bone and uneven cartilage surfaces may cause a grinding sensation (crepitus), especially when reaching overhead or across the chest.
AC Separation: People who develop an AC separation (also called a shoulder separation) usually report a history of falling right onto their shoulder, the result of which is an injury to the ligaments that surround the AC joint. Depending on the severity of the ligament injury, a bump may form above the shoulder due to the separation of the shoulder blade from the collarbone.
All Over the Shoulder
Your shoulder depends on strong tendons, ligaments, and muscles to keep it stable. If these tissues become loose or torn, shoulder instability or dislocation may occur.
Shoulder Instability: Instability is a problem that causes a loose joint. Instability can be caused by a traumatic injury (dislocation) or from overuse. Shoulders that feel unstable may feel as though they will pop out of joint.
Some people have loose ligaments that result in a chronically unstable shoulder called multidirectional instability. These are usually young, athletic women who feel their shoulder not staying tightly in position (subluxation of the shoulder). They often describe a “dead arm” and have excessive range of motion of their shoulder.
Shoulder Dislocation: A dislocation is an injury that occurs when the top of the arm bone becomes disconnected from the scapula. If someone has dislocated his shoulder, then the normal ligaments that hold the shoulder in position may be damaged, and the shoulder has a tendency to pop out of the joint again.