Shoulder Pain

The shoulder is a complex network of muscle, ligaments, and tendons. Some have described the shoulder as a ball and socket, but in reality, it is more like a ball on seal’s nose that is carefully balanced. Because of the wide range of mobility and forces imposed on the joint, it is a common source of pain. Besides the humerus (ball) fitting into the glenohumeral joint (socket), the rotator cuff is pivotal in maintaining stability yet flexible enough to maintain range of motion.

Other joint surfaces in the shoulder complex involve the sternal clavicular joint, acromioclavicular joint, glenohumeral joint, and scapulothoracic surfaces. Classically the glenohumeral joint (humerus into the socket) is what most people refer to as the shoulder joint. Only 25% of the humerus is in contact with the joint, the rest is surrounded by a thick fibrinous cartilage called labrum. Because of the small area of contact, the shoulder has significant instability. Multiple ligaments stabilize the bone into the socket. Pain can originate anywhere from the bones, ligaments, or muscles that surround the joint.

Acromioclavicular and sternoclavicular joints also are important in shoulder range of motion. Coordination between the scapula is important for shoulder function and this largely depends on proper rotator cuff muscles. There are also a group of muscles referred to as scapular stabilizers that help the scapular bone glide over the ribs when the shoulder is moving. These muscles include latissimus dorsi, pectoralis major, and teres major.

In conditions of acute pain after trauma, diagnosis can usually be done with a history, exam, and x-ray. If the pain is not related to acute trauma, it is defined as chronic. Chronic shoulder pain can be caused by a pinched nerve in the cervical spine, inflammation of surrounding bursa, tears in the tendons or ligaments of the rotator cuff, arthritis in the joint.

When diagnosing shoulder pain, it is important to look for the root cause, the history is important with respect to onset, duration, better or worsening factors, location, and radiation. The doctor must also inquire about specific activities that bring the symptoms on such as pitching, throwing, lifting, or doing overhead activities. Past surgeries are also important for diagnosing the cause.  Shoulder pain can range anywhere from dull ache to sharp stabbing symptoms.

If pain is located in the anterolateral shoulder it may signal the beginning of rotator cuff tendinopathy. If untreated it will eventually lead to a tendon tear which will result in weakness and instability of the shoulder. Frozen shoulder (adhesive capsulitis) usually occurs when pain is accompanied by stiffness with lack of mobility. Labral tears can also occur in the front or side part of the shoulder and frequently cause a “catching sensation.”

Pain in the back of the shoulder can be related to teres minor or infraspinatus muscle dysfunction which is a type of rotator cuff tear.  More diffuse areas could involve the trapezius or cervical spine problems. When the cervical spine has a pinched nerve that travels down the shoulder to the arm, a radiating and electrical sensation can be felt shooting down to the fingers.  When patients decrease activity because of pain, frozen shoulder results.

Sports trauma to the shoulder can involve dislocations or fractures. Acromioclavicular joint separation and glenohumeral fractures are only some of the examples that occur with various sports activities. In the non-acute setting, fractures are less likely. If pain is gradual in onset , or lasts for more than 2-4 weeks MRI imaging would be useful for diagnosis.

Medical conditions can correlate with shoulder pain such as heart attack or pathology under the diaphragm.  These internal organs share common entry points of nerve roots into the spine and therefore can be felt as shoulder pain when in fact they are related to something else.

The patient’s age can help suggest causes of pain. For example, older patients are more prone to arthritis which leads to decreased mobility and frozen shoulder. Middle-aged patient’s usually have rotator cuff lesions. These can include full-thickness tears or tendinitis. Patient’s in sports usually suffer with acromioclavicular ligament sprain or subluxation of the joint.

Bursitis shoulder involves inflammation of the bursa.  The bursa if a fluid filled sac in multiple areas of the shoulder joint.  Some lie underneath the rotator cuff, others are near the bony joints.  Bursitis shoulder issues frequently respond well to injection therapy.

Rotator cuff tear.The rotator cuff is composed of 4 muscles: subscapularis, supraspinatus, infraspinatus, teres minor.

Injury to the rotator cuff is particularly common because of the compression forces that it withstands from various activities. Improper athletic technique, lack of exercise, poor posture all induce further injury and degeneration of the joint. The rotator cuff muscles rotate the arm inside and outside. The subscapularis muscle is responsible for generating force for external rotation. The deltoid muscle overlies the entire rotator cuff and is used for lifting the arm up over the head.

Impingement syndrome. Shoulder impingement frequently occurs when part of the rotator cuff gets caught under a bone called the acromion. When the patient tries to lift the arm up, part of the tendon or bursa in the shoulder will get irritated and caused pain shooting to the side of the arm. These symptoms are usually reproducible on a physical exam with the physician and also can be seen using ultrasound in real time. Most of the time the physician will ask a patient to reach upwards in order to reproduce the symptoms.

Tendinitis.  The tendon serves to connect muscles to bones.  Tendinopathy (or injury to the tendon) usually occurs after repetitive activity which leads to excessive strain on the tendon. Eventually the tendon begins to crack and tear causing inflammation. Symptoms usually are worse when the patient is pushing, pulling, extending the arm out, or laying down on the painful side.  Eventually the tendon will tear because it is unable to heal itself without therapy to help correct underlying issues such as mechanics or modifying activities.  Once the tendon thickens, shoulder impingement occurs.

Tendon tear.As tendinitis progresses it eventually leads to tendon tear. As this happens the shoulder becomes weak with diffuse pain along the entire joint. Many patients are unable to sleep at night because symptoms are much worse at that time. Usually tears occur from falls or patients over 40. The patient will have pain with direct pressure. Unfortunately, this results in dramatic loss of function unless corrected or treated.

Biceps Tendon injury.The biceps tendon is used by the arm to help lift objects. Degenerative conditions can cause biceps injury or tear such as through repetitive lifting. A biceps rupture causes pain in the front of the shoulder followed by a noticeable bump in the biceps muscle. Weakness can follow.

Arthritis.  Arthritis in the shoulder usually is referred to as glenohumeral arthritis. The cartilage begins to degenerate from wear and tear. Previous injury predisposes the patient to arthritis development. And frozen shoulder.  Injuries such as dislocation, rheumatoid arthritis, and fractures can result in osteoarthritis. The pain slowly develops over a period of months to years and occurs with nonspecific range of motion.

Tests. Tests to determine cause of pain may include injections or imaging. One example is injecting local anesthetic such as lidocaine into the suspected area of involvement. If the pain improves then the diagnosis can be made. For example, if one suspects supraspinatus injury, injecting lidocaine under ultrasound guidance to the supraspinatus tendon may relieve the pain. If the pain does not improve then it is possible another source of injury is the cause.

X-rays are useful to determine shoulder dislocation, fracture, arthritis. Calcified tendons will also appear on x-ray views.

MRI imaging is particularly useful because it allows visualization of soft tissues such as rotator cuff and tendons.  It is also useful in diagnosing conditions such as tendon rupture, inflammation, tumors, and bone injury such as avascular necrosis.

Ultrasound is used to help diagnose issues with rotator cuff tears, labral tears, tendon damage.  The ultrasound is very useful not only for diagnosis but also during treatment. Your physician is able to see where medication is injected using ultrasound guidance.

In conclusion, the shoulder is a complex network of bones, ligaments, and tendons.  Pain in the joint must be carefully evaluated by your physician.  This includes eliciting a detailed history, reviewing appropriate scans, and conducting a physical exam.  Treatment is highly successful when a combination of rehabilitation and injection techniques are used.

Treatment options for shoulder pain is best achieved through a combination of injection in conjunction with graded rehabilitative exercise.  Individual programs may include a cortisone shot, regenerative medicine, PRP injection, PRP treatment or stem cell therapy which boosts the body’s natural ability to heal.

If your pain does not resolve after a brief period, contact us so that we may help diagnose the problem and treat the underlying cause.  Do not let pain persist or else it may become chronic.