Shoulder problems, including pain, are some of the more common reasons for physician visits for musculoskeletal symptoms. The shoulder is the most movable joint in the body. However, it is an unstable joint because of the range of motion allowed. This instability increases the likelihood of joint injury, often leading to a degenerative process in which tissues break down and no longer function well.

Shoulder pain may be localized or may be referred to areas around the shoulder or down the arm. Other regions within the body (such as gallbladder, liver, or heart disease, or disease of the cervical spine of the neck) also may generate pain that the brain may interpret as arising from the shoulder.

Shoulder structures and functions

The shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) (see diagram). Two joints facilitate shoulder movement. The acromioclavicular (AC) joint is located between the acromion (part of the scapula that forms the highest point of the shoulder) and the clavicle. The glenohumeral joint, to which the term "shoulder joint" commonly refers, is a ball-and-socket joint that allows the arm to rotate in a circular fashion or to hinge out and up away from the body. The "ball" is the top, rounded portion of the upper arm bone or humerus; the "socket," or glenoid, is a dish-shaped part of the outer edge of the scapula into which the ball fits. Arm movement is further facilitated by the ability of the scapula itself to slide along the rib cage. The capsule is a soft tissue envelope that encircles the glenohumeral joint. It is lined by a thin, smooth synovial membrane.

The bones of the shoulder are held in place by muscles, tendons, and ligaments. Tendons are tough cords of tissue that attach the shoulder muscles to bone and assist the muscles in moving the shoulder. Ligaments attach shoulder bones to each other, providing stability. For example, the front of the joint capsule is anchored by three glenohumeral ligaments.

The rotator cuff is a structure composed of tendons that, with associated muscles, holds the ball at the top of the humerus in the glenoid socket and provides mobility and strength to the shoulder joint.

Four filmy sac-like structures called bursa permit smooth gliding between bone, muscle, and tendon. They cushion and protect the rotator cuff from the bony arch of the acromion.

<big><u>Mechanisms of Injury</u></big>

Injuries to the rotator cuff can present in many different ways, it could involve damage to one or multiple of the rotator cuff muscles. These muscles are the supraspinatus, infraspinatus, teres minor, and the subscapularis. The acronym S.I.T.S can be used to remember each muscle of the rotator cuff. These muscles help to stabilize the glenohumeral joint as well as movement of the humerus in space. The supraspinatus is the most commonly injured RC muscle. The supraspinatus is responsible for assisting in abduction of the shoulder joint, it can be damaged in repetitive overhead motions, subacromial impingement, or falling on outstretched arms. The infraspinatus is an external rotator of the humerus and often injured through overhead throwing motions and eccentric deceleration of the arm after a throwing motion.  The teres minor is another external rotator, though it is less commonly injured than the infraspinatus it is stressed due to excessive external rotation of the humerus which is common in overhead throwing athletes. The subscapularis is an internal rotator of the humerus, it can be injured in forced external rotation due to overstretching of the muscle. The degree of severity varies greatly in rotator cuff injuries, it can range from instability to mild tendonitis to full tears requiring surgical intervention.

Diagnosis

Following are some of the ways doctors diagnose shoulder problems:

Medical history and physical exam

  • Medical history (the patient tells the doctor about an injury). For shoulder problems the medical history includes the patient's age, dominant hand, if injury affects normal work/activities as well as details on the actual shoulder problem including acute versus chronic and the presence of shoulder catching, instability, locking, pain, paresthesias (burning sensation), stiffness, swelling, and weakness. Other salutary information includes OPQRST (onset, palliation/provocation, quality, radiation, severity, timing) and a history of issues that could lead to referred pain (pain felt at the shoulder but actually coming from another part of the body) including cervical spine disorders, heart attacks, peptic ulcer disease, and pneumonia. Standardized questionnaires like the Penn Shoulder Score that assess shoulder pain and function can aid in eliciting the required history to make a diagnosis and monitor condition progression.
  • Physical examination of the shoulder to feel for injury and discover the limits of movement, location of pain, and extent of joint instability. The steps to elicit this information are inspection (looking), palpation (feeling), testing range of motion, and performing special maneuvers. Evidence suggests that recovery of shoulder function is not solely dependent on structural healing but heavily relies on restoring range of motion, strength, and coordinated motor control through rehabilitation. Emerging approaches, such as virtual reality–based therapy, have been shown to enhance patient engagement and may improve specific outcomes like shoulder abduction range of motion, while achieving comparable improvements in pain and overall function to traditional therapy.

Diagnostic tests

  • Tests to confirm the diagnosis of certain conditions. Some of these tests include:
  • X-ray
  • Arthrogram—Diagnostic record that can be seen on an X-ray after injection of a contrast fluid into the shoulder joint to outline structures such as the rotator cuff. In disease or injury, this contrast fluid may either leak into an area where it does not belong, indicating a tear or opening, or be blocked from entering an area where there normally is an opening.
  • MRI (magnetic resonance imaging)--A non-invasive procedure in which a machine produces a series of cross-sectional images of the shoulder.
  • Other diagnostic tests, such as injection of an anesthetic into and around the shoulder joint.

Dislocation

Separation

Sternoclavicular separation

Description

While not directly a shoulder problem, this may affect shoulder functionality due to problems with sternoclavicular rotation. A sternoclavicular separation occurs when the sternum separates from the clavicle at the sternoclavicular joint. Sternoclavicular separations (dislocation and subluxation) are rare and generally caused by accident. If the clavicle is separated posteriorly (i.e. the clavicle separates and goes behind the sternum) the situation can be dangerous and the clavicle can cause damage to interior arteries, veins or organs.

Signs and diagnosis

An X-ray or CT Scan may be necessary to accurately diagnose a sternoclavicular separation.

Treatment

Treatment consists of the standard use of plenty of rest, icing, NSAIDs and a sling. The joint may need to be reduced (i.e. put back in place), especially after posterior separations. In severe cases, surgery may be advised.

Rotator cuff tendinopathy (tendinitis, bursitis, impingement syndrome, and rotator cuff tears)

Anatomy

The "rotator cuff" is a group of four tendons that blend together as they attach to the upper end of the arm bone (humerus). These tendons transmit the force of muscles originating on the shoulder blade (scapula) to the arm providing rotational motion and centering or stability of the joint.

Pathology

The rotator cuff tendons degenerate with age. A 2013 liturature review of evidence suggested the Hypothesis that degeneration is related to pinching (or impingement) between the head of the humerus and the acromion is not the cause. Rotator cuff pathology is similar in non-dominant compared to dominant and symptomatic compared to asymptomatic shoulder. About two-thirds of all humans develop rotator cuff tendinopathy if they live to 70 years of age.

Tendinitis is inflammation (redness, soreness, and swelling) of a tendon. In tendinitis of the shoulder, the rotator cuff and/or biceps tendon become inflamed, usually as a result of being pinched by surrounding structures. The injury may vary from mild inflammation to involvement of most of the rotator cuff. When the rotator cuff tendon becomes inflamed and thickened, it may get trapped under the acromion. Squeezing of the rotator cuff is called impingement syndrome.

Subacromial bursitis

Rotator cuff tear

Signs

Signs of these conditions include the slow onset of discomfort and pain in the upper shoulder or upper third of the arm and/or difficulty sleeping on the shoulder, similar condition can have sharp pain or discomfort when the upper shoulder is positioned at certain angles. Tendinitis and bursitis also cause pain when the arm is lifted away from the body or overhead. If tendinitis involves the biceps tendon (the tendon located in front of the shoulder that helps bend the elbow and turn the forearm), pain will occur in the front or side of the shoulder and may travel down to the elbow and forearm. Pain may also occur when the arm is forcefully pushed upward overhead.

Diagnosis

Diagnosis of tendinitis and bursitis begins with a medical history and physical examination. X-rays do not show tendons or the bursae but may be helpful in ruling out bony abnormalities or arthritis. The doctor may remove and test fluid from the inflamed area to rule out infection.

Ultrasound scans are frequently used to confirm a suspected tendinitis or bursitis as well as rule out a tear in the rotator cuff muscles.

Impingement syndrome may be confirmed when injection of a small amount of anesthetic (lidocaine hydrochloride) into the space under the acromion relieves pain.

Treatment

Anti-inflammatory medicines such as aspirin, naproxen or ibuprofen among others can be taken to help with pain. In some cases the physical therapist will use ultrasound and electrical stimulation, as well as manipulation. Gentle stretching and strengthening exercises are added gradually. If there is no improvement, the doctor may inject a corticosteroid medicine into the space under the acromion. However, recent level one evidence showed limited efficacy of corticosteroid injections for pain relief. While steroid injections are a common treatment, they must be used with caution because they may lead to tendon rupture. If there is still no improvement after six to 12 months, the doctor may perform either arthroscopic or open surgery to repair damage and relieve pressure on the tendons and bursae.

In those with calcific tendinitis of the shoulder high energy extracorporeal shock-wave therapy can be useful. For a rotator cuff tear, tentative evidence suggests exercise may reduce pain in the short-term. Combination of exercise and joint mobilization can result in long term benefits. Known gentle exercises include warm water therapy pool exercises that are provided by a trained and licensed physical therapist; approved land exercises to assure free movement of the arthritic area; cortisone injections (administered at the minimum of every six months according to orthopedic physicians) to reduce inflammation; ice and hot moist pact application are very effective. Moist heat is preferred over ice whereas ice is preferred if inflammation occurs during the daytime hours. Local analgesics along with ice or moist heat are adequate treatments for acute pain.

In the case of rheumatoid arthritis, specific medications selected by a rheumatologist may offer substantial relief.

When exercise and medication are no longer effective, shoulder replacement surgery for arthritis may be considered. In this operation, a surgeon replaces the shoulder joint with an artificial ball for the top of the humerus and a cap (glenoid) for the scapula. Passive shoulder exercises (where someone else moves the arm to rotate the shoulder joint) are started soon after surgery. Patients begin exercising on their own about three to six weeks after surgery. Eventually, stretching and strengthening exercises become a major part of the rehabilitation programme. The success of the operation often depends on the condition of rotator cuff muscles prior to surgery and the degree to which the patient follows the exercise programme.

In young and active patients a partial shoulder replacement with a non-prosthetic glenoid arthroplasty may also be a consideration

Arthritis or osteolysis of the AC (acromioclavicular) joint

Description

The acromioclavicular articulation consists of the acromioclavicular ligament and a small disk of cartilage located in between the acromion and the clavicle. This disk can wear down through injury, extreme joint stress (via bodybuilding) or normal wear.

Signs and diagnosis

Pain is perceived on shoulder motion, especially on certain movements. Often a crossover arm test is utilized in diagnosis because this compresses the AC joint, exacerbating the symptoms. X-rays of the shoulder joint may show either arthritic changes of the ac joint or osteolysis.

Treatment

Conservative treatment for this joint is similar to treatments for other types of arthritis, including restricting activity, anti-inflammatory medications (or supplements), physical therapy, and occasionally cortisone shots. If the pain is severe, surgery may be an option. The most common surgical treatment, known as resection arthroplasty, involves cutting a very small portion off the clavicle end and letting scar tissue fill in its place. Some portions of the acromioclavicular ligament may still remain attached.

Treatment

A mnemonic for the basic treatment principles of any musculoskeletal problems is PRICE: Protection, Rest, Ice, Compression, and Elevation:

  • Protection: Guard the shoulder to prevent further injury.
  • Rest: Reduce or stop using the injured area for 48 hours.
  • Ice: Put an ice pack on the injured area for 20 minutes at a time, 4 to 8 times per day. Use a cold pack, ice bag, or a plastic bag filled with crushed ice that has been wrapped in a towel.
  • Compression: Compress the area with bandages, such as an elastic wrap, to help stabilize the shoulder.
  • Elevation: Keep the injured area elevated above the level of the heart. Use a pillow to help elevate the injury.

If pain and stiffness persist, see a doctor.

According to the American Academy of Orthopaedic Surgeons (AAOS) visits to orthopedic specialists for shoulder pain has been rising since 1998 and in 2005 over 13 million patients sought medical care for shoulder pain, of which only 34 percent were related to injury.

References

This article contains and extends text from the public domain document "Questions and Answers about Shoulder Problems", NIH Publication No. 01-4865, available from URL [https://web.archive.org/web/20010910133321/http://www.niams.nih.gov/hi/topics/shoulderprobs/shoulderqa.htm]