Rotator cuff problems are the most common source of shoulder pain seen in a primary care practice; they are typically seen in patients aged 40 years or greater. Degenerative and attritional changes in the tendons are expected with age. The role of impingement of the rotator cuff between the greater tuberosity and the acromion is debated. As the degenerative process advances, a defect may appear in the tendons near their insertion into the proximal humerus. Use of the word tear in this context is commonplace, but misleading. The word tear implies damage that should be repaired, whereas most rotator cuff defects are unrelated to injury and asymptomatic. Furthermore, many patients with a symptomatic rotator cuff defect manage well without surgery. Rotator cuff defects are common with age even in asymptomatic shoulders. Defects are also common in the asymptomatic contralateral shoulder among patients presenting with unilateral shoulder symptoms.

Large defects of the rotator cuff affect shoulder function and can contribute to shoulder dysfunction and even arthrosis of the glenohumeral joint. It is important to identify large defects of the rotator cuff when evaluating patients with shoulder pain. Fatty degeneration of retracted rotator cuff muscles that occurs within a few months of a large tear makes the results of repair much less predictable.

The diagnosis of rotator cuff tendinitis may be a misnomer because it is a degenerative rather than an inflammatory process. A better term may be rotator cuff tendinosis or tendinopathy.
This illness is best considered one of the many tendinoses and enthesopathies with onset in middle age. The diagnosis should be applied with caution to patients younger than 40 years of age. In younger patients, rotator cuff tendinitis is usually secondary to some other process, such as instability. A defect of the rotator cuff tendon in a younger person—including an isolated tear of the subscapularis tendon—is typically a relatively high-energy injury. Such tears are rare but important to identify and repair. Careful physical examination can verify that the rotator cuff is unlikely to have a large defect (see later discussion). Any doubt merits referral to an experienced shoulder surgeon.

Most patients with pain due to rotator cuff tendon dysfunction are older than age 40 years. Pain over the deltoid, especially during overhead activities and internal rotation, and weakness of shoulder elevation and external rotation are diagnostic features. Superior shoulder pain suggests acromioclavicular joint problems. Muscle atrophy over the scapula (supraspinatus and infraspinatus) suggests a large tendon defect extending posteriorly.

Biceps tendinitis of the shoulder is best considered part of rotator cuff tendinopathy. Rupture of the long head of the biceps results in a “Popeye” deformity of the arm but does not affect function. This contrasts with a rupture of the distal insertion of the biceps tendon into the radius, which causes weakness of supination. Operative treatment of proximal biceps ruptures is for pain relief alone and is controversial.

The glenohumeral joint has little inherent stability; stability is heavily dependent on static capsuloligamentous and dynamic musculotendinous restraints. Two general categories of glenohumeral instability constitute the majority of such problems: traumatic unidirectional instability and atraumatic multidirectional instability.

Traumatic dislocation of the glenohumeral articulation almost always results in anterior dislocation of the humeral head from the glenoid articular surface of the scapula. Posterior glenohumeral dislocations are uncommon and are often related to a seizure or electric shock injury. Traumatic posterior dislocations are often fracture dislocations of the glenoid articular surface.

Traumatic anterior dislocation nearly always disrupts the anterior attachment of the glenoid labrum to the glenoid articular surface (Bankart lesion). The labrum is a ring of fibrous cartilage that helps to deepen the relatively shallow glenoid articular surface and is the site of attachment of the all-important glenohumeral ligaments. The likelihood that a patient who has had one traumatic anterior dislocation of the shoulder will have recurrent dislocations is related to the age of the patient at the time of the first dislocation. As many as 80% of patients younger than 20 years at the time of first diagnosis will have another dislocation. Older patients are less likely to have a recurrent dislocation, but tearing of the rotator cuff may occur. Recurrent anterior dislocation usually requires surgical treatment consisting of reattachment of the anterior portion of the labrum to the glenoid margin in addition to tightening of any redundant anterior capsule.

Atraumatic instability is usually related to laxity of a number of capsular restraints. In many cases, the patient may have a connective tissue disorder. Other patients, such as competitive swimmers, may develop multidirectional instability. This type of instability usually responds to a program of specific exercises intended to strengthen the dynamic muscular stabilizers of the shoulder. Athletes may also need to modify their technique; a good coach or trainer can be useful in this regard.

Patients who can actively and voluntarily dislocate their shoulder should be approached with caution. Often, a subtle underlying psychiatric condition is present. Cases in which the voluntary dislocation is habitual—often, the patient has derived some attention or reward from the ability to dislocate a shoulder—can be difficult to manage. This should be distinguished from situations in which the voluntary dislocation is positional—the patient can reproduce the instability by placing the arm in certain position but is averse to doing so.

Idiopathic adhesive capsulitis, or frozen shoulder syndrome, is a characteristic symptom complex of pain and tenderness located diffusely about the anterior and posterior regions of the shoulder joint capsule. It is more common among diabetic patients. The term “frozen shoulder” has, unfortunately, become imprecise. Idiopathic adhesive capsulitis should be distinguished from other forms of shoulder stiffness—posttraumatic stiffness in particular. Active and passive motions of the glenohumeral joint are limited and painful. The condition is self-limiting, although improvement of motion can take months to years. Operative treatment is controversial.

Osteoarthritis of the glenohumeral joint is relatively uncommon. It causes symptoms at rest that are exacerbated by shoulder use. The patient may note a “grinding” sound with motion. Pain, crepitation, and diminished motion may be noted on examination. Rheumatoid arthritis frequently involves the glenohumeral joint and usually gives a picture of symmetric bilateral inflammatory changes.

Degenerative changes of the acromioclavicular joint are common, even in asymptomatic individuals. Symptoms should be ascribed to the radiographic changes with care. The pain is typically superior rather than anterolateral as with rotator cuff tendon problems. Examination and diagnostic injection are described later.

Shoulder sepsis is typically hematogenous but may also be postoperative or, rarely, postinjection. Laboratory analysis of the aspirate confirms the diagnosis. Operative débridement and parenteral antibiotics are required.