What Causes Shoulder Pain?
The shoulder is one of the most complex joints in the human body; made up of bones, cartilage, ligaments, muscles, and tendons. All of the components of the shoulder work together to move the arm freely through 360-degrees of motion and perform specialized tasks, such as accurately throwing a baseball and lifting heavy loads above your head. However, the same mobility and flexibility that allows the shoulder to be so versatile also leaves it less stable than other joints of the body, making it more susceptible to injury. Shoulder pain, one of the most common orthopaedic conditions, stems from damage caused by disease, chronic overuse or acute injury to one or more of the components of the shoulder. Oftentimes these are soft tissue injuries, like tendinitis or rotator cuff tears, but the three major bones of the shoulder—the humerus, scapula and clavicle—can also be damaged through overuse or injury.
Common Causes of Shoulder Pain
Bursitis - Shoulder bursitis is caused by inflammation of the bursa, a small, fluid-filled sac in the shoulder that reduces friction between the different components of the joint. When placed under repeated stress, as happens during repetitive motions like throwing or overhead lifts, the bursa can overfill with fluid, leading to pain and stiffness.
Tendinitis - Tendinitis occurs when the tendons and muscles that comprise the shoulder are injured, typically from chronic overuse. This condition generally develops gradually over time and is very prevalent in people who perform a lot of repeated, overhead movements, like swimmers, pitchers and tennis players, and laborers. It can also have postural origin, since keeping the arm in the same position for an extended period of time, like sleeping on the same shoulder night after night, can lead to tendinitis.
Bicep Tendon Tears - There are three biceps tendons in each arm; two that connect the biceps muscle to the shoulder and one that connects the biceps muscle to the elbow. Biceps tendon tears occur when chronic overuse causes repeated stress to continually degrade the tendon, or when a sudden, traumatic injury overloads the tendon and it tears.
Rotator Cuff Tears - The rotator cuff, a group of four muscles that attach the humerus (upper arm bone) to the shoulder blade, is one of the most crucial components of the shoulder. It allows the muscles and tendons of the shoulder to lift and rotate the humerus and is essential to almost every basic and complex movement we require of the joint. The rotator cuff can be injured through acute injury or it can tear gradually over time; in any case, injury to the rotator cuff is very painful and severely limits the shoulder's ability to move and function as intended.
SLAP - The labrum is a ring of firm, fibrous tissue that surrounds the shoulder socket (glenoid) and stabilizes the joint. When the top (superior) portion of the labrum is torn, it is commonly referred to as a SLAP tear, an acronym meaning "superior labrum anterior and posterior." This literally translates into a tear at "the top part of the labrum, from the front to the back."
Acromioclavicular Joint Separation - The acromioclavicular (AC) joint is the point in the shoulder where the collarbone (clavicle) and the acromion of the shoulder blade are connected by ligaments. An AC joint separation occurs when these ligaments are strained or separated, typically from a sharp blow to the shoulder, and can be "graded" on a scale of one to six, with six being the most severe. Grade 1 separations generally involve a sprain of the AC ligament, while Grade 6 separations involve total tears of the ligaments and noticeable deformity in the shoulder.
Impingement - Shoulder impingement occurs when the rotator cuff tendon and the bursa are squeezed between the acromion and humerus bones in the subacromial space. Over time, this pressure on the soft tissues of the shoulder can cause micro-tearing of the rotator cuff and degeneration of the tendon. If left untreated, this can progressively lead to a full tear of the rotator cuff.
Instability - Shoulder instability is a degradation of the stability of the ball and socket joint that makes up the shoulder. A chronic condition in which the head of the humerus (the "ball") repeatedly slips out of the glenoid cavity (the "socket"), shoulder instability can lead to lasting damage to the soft tissues of the shoulder if untreated. These repeated dislocations can reduce on their own, in which case they are known as subluxations, but a complete dislocation requires medical intervention to be corrected.
Shoulder Arthritis - Arthritis literally translates to "inflammation of the joint," and describes any disease process which leads to cartilage loss. Cartilage serves an incredibly important role in joints of the body, as it "cushions" the space and prevents bone-on-bone contact. Arthritis occurs in every major and minor joint and can be very painful, because the wearing down of cartilage causes bones to grind against one another. This leads to increasing stiffness, pain, swelling and decreased use of the shoulder. The three principal forms of shoulder arthritis are osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis.
Fracture - Fractures occur when sufficient force acts upon a bone to break it. The three bones of the shoulder most susceptible to fractures are the clavicle (collarbone), proximal humerus (upper arm bone), and the scapula (shoulder blade). Generally speaking, these fractures can affect people of any age and are often the result of falls, but they can also be frequently found in young athletes injured during sport.
Adhesive capsulitis - Colloquially known as frozen shoulder, adhesive capsulitis is a painful condition in which the thin, flexible capsule surrounding the shoulder develops adhesions and becomes rigid and thick. This hardening of the capsule makes it increasingly difficult to move the shoulder and can result in pain and significant loss of range of motion in the joint.
How is the cause of shoulder pain diagnosed?
Given the wide variety of common shoulder conditions discussed above, one might wonder how to possibly narrow down the cause of their pain. The first step in determining what is causing shoulder pain is to schedule an appointment with an orthopaedic surgeon and allow them to help diagnose your issue. An orthopaedic surgeon will take a detailed individual and family medical history; conduct a physical examination during which he or she will manipulate your shoulder to assess its range of motion, strength and resilience; and order any necessary diagnostic tests, such as x-ray studies, an MRI or a CT scan. Armed with this information, a physician will then use their knowledge and experience to narrow down your shoulder pain to its most likely cause and work with you to develop a plan of action.
When should I seek medical help?
Generally speaking, it is advisable to seek medical treatment as soon as you start experiencing consistent pain and discomfort in your shoulder. While it is likely that your injury is manageable with non-invasive or minimally-invasive treatments, some conditions of the shoulder require immediate surgical intervention for optimal outcomes, so waiting to seek treatment is not in your best interest. You should always seek medical treatment if you experience shoulder pain that is not alleviated by several days of rest, ice, and anti-inflammatory medications. There is no reason to live with shoulder pain when there are so many effective treatment options available; delaying medical treatment may only prolong your suffering.
What are the treatment options for shoulder pain?
When properly diagnosed, most shoulder pain can be treated without surgery. There are an array of surgical and non-surgical treatment options for shoulder pain. Based on your history, physical exam and applicable diagnostic test results, a physician could recommend lifestyle changes, like activity modification and diet; medication; physical therapy; minimally-invasive treatments like orthobiologics or corticosteroid shots; and, if necessary, surgery. Regardless of which treatment option is deemed best for you, a physician will also work with you to develop preventative techniques to stop an injury from returning after treatment, and to prevent the same issue from affecting the other shoulder.