Definition

Osteoarthritis of the glenohumeral joint occurs when there is loss of articular cartilage that results in narrowing of the joint space (Fig. 19.1). Synovitis and osteocartilaginous loose bodies are commonly associated with glenohumeral arthritis. Pathologic distortion of the articular surfaces of the humeral head and glenoid can be due to increasing age, overuse, heredity, alcoholism, trauma, Gaucher disease (lipid storage disease), or metabolic disease of bone.

In looking at glenohumeral arthritic conditions, one must consider osteonecrosis both as an etiologic entity and as a related endpoint to the disease. Most of the information about osteonecrosis of the humeral head is extrapolated from the research findings of the disorder of the hip. The major difference between osteonecrosis of the hip and osteonecrosis of the humeral head is that the shoulder bears less weight than the hip. Risk factors are corticosteroid use, radiation therapy, and sickle cell anemia, but its presence in a medically uncomplicated adolescent competitive swimmer [1] does seem to suggest that it may be more common than previously thought.

Shoulder osteoarthritis is most commonly seen beyond the fifth decade and is more common in men. Long-standing complete rotator cuff tears, multidirectional instability from any cause, lymphoma [2] (chronic lymphocytic lymphoma or immunocytoma), or prior capsulorrhaphy for anterior instability [3] can predispose to glenohumeral arthritis.

Acute septic arthritis should not be heedlessly ruled out in the face of severe osteoarthritis [4]. The medical history should include any history of fracture, dislocation, rotator cuff tear, repetitive motion, metabolic disorder, immunosuppression, chronic glucocorticoid administration, and prior shoulder surgery.

Symptoms

Symptoms include shoulder pain intensified by activity and partially relieved with rest. Pain is usually noted with all shoulder movements. Major restriction of shoulder motion and disuse weakness or pain inhibitory weakness are common and potentially progressive. Resultant adhesive capsulitis may be the primary clinical presentation. Pain is typically restricted to the area of the shoulder and may be felt around the deltoid region but not typically into the forearm. Pain is generally characterized as dull and aching but may become sharp at the extremes of range of motion; it is typically worse in the supine position and in attempting to sleep on the arthritic side. Pain may interfere with sleep and may be worse in the morning. Neurologic symptoms, such as numbness and paresthesias, should be absent.

Physical Examination

Restriction of shoulder range of motion is a major clinical component, especially loss of external rotation and abduction. Both active and passive range of motion is affected in shoulder arthritis, compared with only active motion in rotator cuff tears (passive range is normal in rotator cuff injuries unless adhesive capsulitis is present). Pain increases when the extremes of the restricted motion are reached, and crepitus is common with movement. Tenderness may be present over the anterior rotator cuff and over the posterior joint line.

Several well-described tests for examination of the shoulder are commonly used in clinical practice (e.g., Neer, Hawkins-Kennedy, Yergason, painful arc, and compression-rotation test). Pooled sensitivity and specificity range from 53% to 95%, yet meta-analysis has demonstrated that use of any single shoulder examination test to make a diagnosis cannot be unequivocally recommended. Combinations of tests provide better accuracy, but marginally so. These findings seem to provide support for stressing a comprehensive clinical examination [5].

If acromioclavicular joint osteoarthritis is an accompanying problem, the acromioclavicular joint may be tender. There may be wasting of the muscles surrounding the shoulder because of disuse atrophy. Sensation and deep tendon reflexes should be normal. In patients with inconsistent physical examination findings and questionable secondary gain issues, the American Shoulder and Elbow Surgeons subjective shoulder scale has demonstrated acceptable psychometric performance for outcomes assessment in patients with shoulder instability, rotator cuff disease, and glenohumeral arthritis [6]. Additional scoring systems, such as the Hospital for Special Surgery score and the validated Western Ontario Osteoarthritis of the Shoulder Index, may be of clinical or research utility [7].

Functional Limitations

Any activities that require upper extremity strength, endurance, and flexibility can be affected. Most commonly, activities that require reaching overhead in external rotation are limited. These include activities of daily living (such as brushing hair or teeth, donning or doffing upper torso clothes) and activities such as throwing or reaching for items overhead. If pain is severe and constant, sleep may be interrupted, sleep-wake cycle disruption may occur, and situational reactive depression is not uncommon, especially with a shoulder pain syndrome that has exceeded 3 months [8].

Diagnostic Studies

Routine shoulder radiographs with four views (anteroposterior internal and external rotation, axillary, and scapular Y) are generally sufficient for evaluating loss of articular cartilage and glenohumeral joint space narrowing (Fig. 19.2). Varying degrees of flattening of the humeral head, marginal osteophytes, calcific tendinitis, subchondral cysts in the humeral head and glenoid, sclerotic bone, bone erosion, and humeral head migration may be seen. Specifically, if there is a chronic rotator cuff tear that is contributing to the destruction of the articular cartilage, the humeral head will be seen pressing against the undersurface of the acromion. Associated acromioclavicular joint arthritis can be seen on the anteroposterior view.

Conventional magnetic resonance imaging is the “gold standard” to assess soft tissues for rotator cuff tear; but when more sensitive evaluation of the labrum, capsule, articular cartilage, and glenohumeral ligaments is required or when a partial-thickness rotator cuff tear is suspected, magnetic resonance arthrography with intra-articular administration of contrast material may be required to visualize these subtle findings [9]. Paralabral cysts (extraneural ganglia), which can result with posterior labrocapsular complex tears and cause suprascapular nerve compression, may be visualized on magnetic resonance imaging [10].

Computed tomography may have a unique role in finding posterior humeral head subluxation relative to the glenoid in the absence of posterior glenoid erosion [11]. A rise in popularity of diagnostic ultrasonography in musculoskeletal medicine is undeniable. The modality may play a role in the diagnosis of full-thickness rotator cuff tear in experienced hands, but significant inter-rater reliability has been called into question [12,13], and diagnostic ultrasonography would play a minimal role in the diagnosis of glenohumeral arthritic conditions.