Both glenohumeral and acromioclavicular arthritis are common causes of pain in the shoulder

The glenohumeral joint is the third most common joint requiring replacement for end stage arthritis after the hip and knee respectively ¹

Primary osteoarthritis is a diagnosis of exclusion as inflammatory arthritis, crystal arthropathy, post-traumatic arthropathy, neuropathic arthropathy, or avascular necrosis can all lead to end stage shoulder arthritis

The true incidence of arthritis of the shoulder is unknown:

1. 
   

   Glenohumeral arthritis:

   
   
   
   
   1. 
      

      More common in women than men

      
      
   2. 
      

      Higher incidence after the age of 60 ²

      
      
   3. 
      

      Increased risk of developing osteoarthritis with past history of shoulder dislocation ³

      
      
   4. 
      

      Genetic contribution is poorly understood, although primary osteoarthritis of the shoulder is likely due to an interplay between genetic predisposition and environmental factors. ⁴

   
   
2. 
   

   Acromioclavicular arthritis:

   
   
   
   
   1. 
      

      More common than glenohumeral arthritis

      
      
   2. 
      

      Common in overhead manual laborers, weight lifters, and overhead athletes

      
      
   3. 
      

      Increased incidence in individuals performing manual labor ⁵

      
      
   4. 
      

      Can also be due to a post-traumatic etiology after dislocation or distal clavicle fracture.

Clinical symptoms include progressive upper extremity pain, trouble sleeping, and difficulty performing work-related tasks or activities of daily living:

1. 
   

   Often complain of deep aching within or on top of the shoulder, and catching or popping with certain motions.

Commonly associated conditions include biceps tendonopathy, glenoid bone wear, rotator cuff tear, and labral degeneration:

1. 
   

   Rotator cuff tears are often seen in conjunction with arthritis but can be difficult to appreciate clinically due to overall loss of motion and pain with examination maneuvers.

Treatment:

1. 
   

   Operative and nonoperative management options depending on the degree of disability and loss of function.

Osteology:

1. 
   

   The shoulder consists of the glenohumeral, acromioclavicular, scapulothoracic, and sternoclavicular joints

   
   
2. 
   

   The shoulder itself is a ball and socket joint consisting of the glenoid medially and the humeral head laterally:

   
   
   
   
   1. 
      

      Hyaline cartilage covers the articulating portions of the joint

      
      
   2. 
      

      The humerus is 20–30 degrees retroverted

      
      
   3. 
      

      The glenoid is generally neutral to several degrees retroverted.

   
   
3. 
   

   The shoulder includes the scapula (the superior portion), the acromion (the articulating portion), the glenoid, and the coracoid process anteriorly:

   
   
   
   
   1. 
      

      The coracoid serves as the attachment site for the coracobrachialis, pectoralis minor, coracoclavicular ligaments, coracoacromial ligament, coracohumeral ligament, and the short head of the biceps.

   
   
4. 
   

   The acromioclavicular joint is a diarthrodial joint

   
   
5. 
   

   The distal clavicle attaches to the acromion with fibrocartilage joint surfaces and a disc separating the two bony ends with a capsule surrounding the joint.

Vasculature:

1. 
   

   Blood supply to the humeral head is provided by the posterior and anterior humeral circumflex vessels. The posterior circumflex is believed to provide most of the blood supply: ⁶

   
   
   
   
   1. 
      

      The ascending branch of the anterior circumflex artery is the arcuate artery, which runs lateral and parallel to the bicipital groove.

      
      
   2. 
      

      Branches of the suprascapular artery also contributes blood supply to the shoulder.

   
   
2. 
   

   The acromioclavicular joint blood supply derives from the suprascapular artery and the thoracoacromial artery.

Nerves:

1. 
   

   Shoulder joint:

   
   
   
   
   1. 
      

      Axillary nerve

      
      
   2. 
      

      Suprascapular nerve

      
      
   3. 
      

      Lateral pectoral nerve.

   
   
2. 
   

   Acromioclavicular joint:

   
   
   
   
   1. 
      

      Suprascapular nerve

      
      
   2. 
      

      Lateral pectoral nerve.

Definition:

1. 
   

   Loss of articular cartilage between the humeral head and glenoid fossa

   
   
2. 
   

   Diagnosis is made by history and clinical examination in conjunction with radiographs.

Clinical presentation:

1. 
   

   Age of onset typically in patients older than 50 but can present earlier in patients with a prior traumatic shoulder injury

   
   
2. 
   

   Common complaints include deep aching in the shoulder that is worse with activity:

   
   
   
   
   1. 
      

      May have minimal to no pain at rest.

   
   
3. 
   

   Difficulty sleeping, especially on the affected shoulder

   
   
4. 
   

   Normally pain begins with no inciting event and tends to worsen with time

   
   
5. 
   

   Loss of range of motion (particularly external rotation).

Evaluation:

1. 
   

   Physical examination:

   
   
   
   
   1. 
      

      Neurovascular upper extremity examination:

      
      
      
      
      • 
        

        i. Sensation, strength, and pulses to rule out cervical spine pathology.

      
      
   2. 
      

      Shoulder examination:

      
      
      
      
      • 
        

        i. Loss of range of motion passively and actively with end range-of-motion pain

        
        
      • 
        

        ii. Forward flexion

        
        
      • 
        

        iii. Abduction

        
        
      • 
        

        iv. External rotation

        
        
      • 
        

        v. Internal rotation (behind the back).

      
      
   3. 
      

      Pain to palpation throughout the shoulder is common. Palpate:

      
      
      
      
      • 
        

        i. Acromioclavicular joint

        
        
      • 
        

        ii. Biceps groove

        
        
      • 
        

        iii. Lesser and greater tuberosities

        
        
      • 
        

        iv. Acromion

        
        
      • 
        

        v. Scapular spine

        
        
      • 
        

        vi. Scapular medial border.

      
      
   4. 
      

      Joint effusion is sometimes present

      
      
   5. 
      

      Crepitus with range of motion

      
      
   6. 
      

      Anterior shoulder may appear flattened because of posterior subluxation:

      
      
      
      
      • 
        

        i. It is often difficult to determine the integrity of the rotator cuff secondary to patient’s pain with range of motion and overall limitation of range of motion (especially internal and external rotations):

        
        
        
        
        • 
          

          Test strength in internal/external rotation, Jobe test.

   
   
2. 
   

   Imaging:

   
   
   
   
   1. 
      

      Shoulder radiographs are normally diagnostic:

      
      
      
      
      • 
        

        i. A full series of shoulder radiographs include an anteroposterior (AP) view, a Grashey view, a lateral (Scapular Y) view, and an axillary view:

        
        
        
        
        • 
          

          AP view may show loss of joint space (although this is better visualized in a Grashey view) with osteophytes of the proximal humerus or loose bodies. The humeral head should be concentric within the glenoid (▶ Fig. 15.1 ).

          
          
        • 
          

          Grashey view is the true AP view of the shoulder and best shows the glenohumeral joint.

          
          
        • 
          

          Axillary view should be examined to determine wear of the glenoid. Often the humeral head is posteriorly subluxed in osteoarthritis.

          
          
        • 
          

          Scapular Y view is helpful to identify locations of loose bodies and to evaluate the bony architecture of the shoulder further.

        
        
      • 
        

        ii. Features common to osteoarthritis of the shoulder include loss of joint space, loose bodies, osteophytes along the humeral head (goat’s beard), subchondral cysts, and glenoid bone loss which is generally posterior and often accompanied by posterior humeral head subluxation.

      
      
   2. 
      

      Further evaluation of the glenohumeral joint bone structure can be done with a computed tomography (CT) imaging series to examine the degree of arthritis present and rotator cuff integrity versus a magnetic resonance imaging (MRI) which better visualizes the rotator cuff at the expense of bone detail.

      

   
   
3. 
   

   Classification:

   
   
   
   
   1. 
      

      Walch classification system of glenoid bone wear is commonly used (▶ Table 15.1 ).

Treatment:

1. 
   

   Nonoperative:

   
   
   
   
   1. 
      

      Avoidance of activities that exacerbate pain

      
      
   2. 
      

      Physical therapy and at-home stretching with goal to maintain range of motion and strength of periscapular muscles

      
      
   3. 
      

      Ice or heat

      
      
   4. 
      

      Medications:

      
      
      
      
      • 
        

        i. Nonsteroidal anti-inflammatory drugs

        
        
      • 
        

        ii. Acetaminophen

        
        
      • 
        

        iii. Oral steroid dose pack.

      
      
   5. 
      

      Corticosteroid joint injections versus joint lubrication injections (hyaluronic acid) versus biologics (minimal evidence of efficacy).

   
   
2. 
   

   Operative:

   
   
   
   
   1. 
      

      Surgery is indicated when nonoperative measures fail

      
      
   2. 
      

      Treatment depends on patient factors which include age, degree of glenoid bone wear, glenoid version, medical comorbidities, associated pathology (i.e., rotator cuff tears), and work status

      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      

      Table 15.1 Modified Walsh classification

      Type A Concentric wear with a well-centered humeral head	A1 Minor central erosion of the glenoid
      	A2 Deep central erosion with line connecting the anterior and posterior glenoid bisecting the humeral head
      Type B Asymmetric posterior glenoid wear with posterior subluxation of the humeral head	B1 Posterior joint space narrowing with no posterior bone loss
      	B2 Biconcave glenoid with retroversion of the glenoid and bone loss present
      	B3 Posterior wear with retroversion >15 degrees or humeral head subluxation >70%
      Type C Dysplastic glenoid retroversion present	Glenoid retroversion of >25 degrees
      Type D	Glenoid anteversion or anterior humeral head subluxation

      

      
      
   3. 
      

      In early arthritis, arthroscopic debridement and capsular releases can be performed:

      
      
      
      
      • 
        

        i. Modest early results are common, with a high reoperation rate in both the short and long terms. ⁷

      
      
   4. 
      

      Hemiarthroplasty is considered in young patients with end stage arthritis or patients with severe glenoid bone loss with an intact rotator cuff:

      
      
      
      
      • 
        

        i. Hemiarthroplasty has a higher revision rate than primary total shoulder arthroplasty secondary to pain from glenoid-sided arthrosis, which commonly develops. ⁸

      
      
   5. 
      

      The most effective treatment for advanced arthritis of the glenohumeral joint is total shoulder arthroplasty, in which the glenoid and humeral head are resurfaced with metal and polyethylene. Anatomic total shoulder arthroplasty is the traditional treatment for shoulder arthritis but there are increasing indications for which reverse shoulder arthroplasty is more appropriate due to severe bone wear or accompanying pathology. Total shoulder arthroplasty requires the rotator cuff to be intact (▶ Fig. 15.2 ):

      
      
      
      
      • 
        

        i. Among patients who undergo total shoulder arthroplasty, 90% experience complete or nearly complete pain relief with improved range of motion after surgery. ⁸