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, or alcoholism. Chronic oral exogenous glucocorticoids account for about 10% of arthroplasties performed annually in the United States; variation exists among practitioners as to what doses are considered “high dose.” Other causation such as intravenous drug use, trauma, Gaucher disease (lipid storage disease), and metabolic disease of bone may also play a role. It is worth noting that the epidemic of intravenous drug use, especially heroin, has resulted in a higher incidence of femoral avascular necrosis (AVN) and while humeral head AVN is not as widely reported, it is certainly a documented etiology. 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 versus 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 does seem to suggest that it may be more complex interaction between event and genetic predisposition than previously thought.

Osteoarthritis of the shoulder.

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 (chronic lymphocytic lymphoma or immunocytoma), or prior capsulorrhaphy for anterior instability can predispose to glenohumeral arthritis.

Acute septic arthritis should not be heedlessly ruled out in the face of severe osteoarthritis, especially with a history of intravenous drug use. 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. The pain is generally characterized as dull and aching; however, it may become sharp at the extremes of range of motion and is typically worse in the supine position if attempting to sleep on the arthritic side. Pain may interfere with the sleep-wake cycle and may be worse in the morning, as with all arthritic complaints. 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 to 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 performed by experienced clinicians provide better accuracy, but marginally so. As with all musculoskeletal complaints, the physical exam should be approached in a systematic fashion based on functional, not just regional, complaints. Beginning with observation (e.g., winging, skin atrophy), palpations, neurosensory, active, and passive range of motion, motor, and special tests (apprehension, acromioclavicular shear, Yergason, drop-arm, etc.). 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. 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.

Functional Limitations

The shoulder is richly innervated, so patients may complain of severe pain that limits functional activities. 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. As with any chronic pain syndrome, sleep may be interrupted; sleep-wake cycle disruption may occur, which affects sleep architecture and hormonal cycles. Situational reactive depression is common. This may lead to amotivational syndromes, poor therapy response, exaggerated pain behaviors, and an overall poor clinical outcome even with good surgical results.

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.

Radiograph typical of glenohumeral osteoarthritis.

Conventional magnetic resonance imaging (MRI) is the “gold standard” to assess soft tissues for rotator cuff tear. However, comparison of three-dimensional MRI osseous models have been shown to be statistically equivalent to three-dimensional computed tomography (CT), suggesting the more economical of the two may be adequate in clinical practice. 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 subtle findings. Paralabral cysts (extraneural ganglia), which can result in posterior labral capsular complex tears and cause suprascapular nerve compression, have only been shown to be visualized on MRI.

CT may have a unique role in finding posterior humeral head subluxation relative to the glenoid in the absence of posterior glenoid erosion. 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, and diagnostic ultrasonography would play a minimal role in the diagnosis of glenohumeral arthritic conditions.

Electrodiagnostic studies help rule out neurologic conditions (e.g., cervical radiculopathy, axillary neuropathy). The sensory irritative component of spinal or peripheral nerve irritation will usually yield a normal result, but H reflexes to median nerve stimulation at the level of the elbow may be suggestive of C5-C6 radiculitis, whereas findings on needle electromyography would be normal.

Complete blood counts, coagulation profile, erythrocyte sedimentation rate, and blood cultures may be in order. In addition, the author encourages that any woman with shoulder pain recalcitrant to seemingly appropriate treatment be considered for mammography.

Differential Diagnosis

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