The glenohumeral joint has three degrees of freedom and functions to perform the following movements at the glenohumeral articulation: flexion/extension; adduction/abduction; and internal and external rotation. Forward flexion is also known as “elevation”, and adduction is also known as “cross body abduction” or “horizontal abduction” (See figures 1 -4).
5 internal rotation
6 external rotation
1: Shoulder elevation. Patients should be able to elevate the arm such that it is parallel with the torso, i.e., about 180 degrees
Figure 2: Shoulder adduction. Patients should able to reach across the midline, and ideally to be able to touch the contralateral shoulder.
Figure 3: Shoulder internal rotation. Patients are asked to reach behind their backs. Internal rotation can be quantified by noting the approximate spinal level the patient can reach with his or her thumb, as shown.
Figure 4: Shoulder external rotation is assessed by asking the patient to place his or her arm at the side, flex the elbow to 90 and rotate externally. Because the scapular is not oriented perfectly with the torso, the glenohumeral joint is already externally rotated 30 degrees when the arm is pointing directly forward. The normal glenohumeral joint should be able to externally rotate an addition 60 degrees, as shown here.
Glenoid version refers to the relationship between the glenoid cavity and the humeral head. It is a radiographic measurement determined by the angle between the glenoid line and the line perpendicular to the scapular axis. The glenoid is normally slightly retroverted. In addition, the humeral head and neck are also retroverted from the humeral shaft (with the anterior plane defined by the position of the humeral epicondyles at the elbow). Normal humeral version is 20-30° of retroversion. Deviations from normal version can disturb normal mechanics and lead to arthritic changes.
- Rheumatoid Arthritis
- Systemic autoimmune disease of the synovium. Synovial inflammation and soft tissue break down at the shoulder results in wear of the glenoid articular cartilage and medialization of the humeral head.
- Post-traumatic arthritis
- Disruption of the articular surface can occur after a humeral fracture or dislocation. The damage with dislocation can be from the impact of the dislocation episode or from microtrauma inflicted by chronic instability.
- Crystalline arthritis
- Gout and Calcium Pyrophosphate Dihydrate Deposition Disease (CPPD) result in the deposition of crystals within the joint space which cause synovial inflammation and resultant cartilage damage.
- Morphological and arthritic changes result from loss of blood supply to the humeral head. Osteonecrosis can appear from trauma, use/abuse of alcohol or steroids, hemoglobinopathies, among other causes. It may also be idiopathic (no known cause).
- Charcot Arthropathy
- Loss of sensation and proprioception in the joint results in repetitive microtrauma and joint degeneration. Charcot Arthropathy of the shoulder is often related to cervical spine syrinx.
- Rotator cuff arthropathy
- Tears of the rotator cuff tendons disturb normal biomechanics (as the rotator cuff is an important shoulder stabilizer). Such tears produce abnormal humeral head contact, leading to breaking down of the articular surfaces.
- Septic Arthritis
- The white cell response to infection can damage articular cartilage.
Patients with glenohumeral arthritis present with shoulder pain and stiffness. Taking a thorough history with these patients is key as it can determine the etiology of the disease.
Patients with glenohumeral osteoarthritis are typically over 50 years old and present with a chief complaint of pain. The pain is usually insidious in onset, progressive, chronic, and worsens with activity. Discomfort may lead to nocturnal awakening, especially when lying on the affected side, and patient
’s patients typically have functional limitations due to a decreased range of motion. On physical exam, the affected extremity may be atrophic secondary to disuse. Patients have tenderness over the posterior joint line and crepitus with motion of the joint. The most dramatic finding is typically decreased range of motion which is most pronounced with external rotation.
Imaging of the glenohumeral joint starts with radiographs taken at three views: AP, lateral and scapular (also known as a “Y”) view. Findings on these radiographs often lead to the etiology of the arthritis (
figure 7Figure 5).
Figure 75: Osteoarthritis of the shoulder is shown, with bony sclerosis, osteophyte formation and superior migration of the humeral head. (C ourtesy
radiopedia Case courtesy of Radiopedia case 43425.
Advanced imaging such as CT and MRI are indicated for pre-operative planning as they provide the surgeon with enhanced imaging of glenoid morphology and rotator cuff pathology.
Treatment Options and Outcomes
Mainstays of non-operative treatment for glenohumeral arthritis consist of physical therapy, NSAID
SNSAIDs, activity modification, and injections.
Of note, RA can be very well controlled with disease-modifying antirheumatic drugs (DMARD). Intraarticular injections of corticosteroids act to reduce inflammation. However, arthritis is a progressive disease and medical treatment exhausts quickly.
A hemiarthroplasty involves replacing the humeral head with a stemmed prosthesis. It is indicated for patients who have failed
conservative non-operative treatment with an intact glenoid and articular damage to the humerus. The best results are seen in patients with concentric glenoids and intact rotator cuffs.
In a total shoulder arthroplasty, the arthritic humeral head is replaced with a metal ball fixed to a stem inserted into the humeral shaft and the glenoid is resurfaced with a polyethylene insert (see
figure 8Figure 6). This procedure is best for patients with a moderate to low activity level. Patients need good bone stock and an intact or repairable rotator cuff. Patients treated with total shoulder arthroplasty see good pain relief and reliable range of motion with a 10-year survival rate of 92-95%. Common complications include component loosening, infection, fracture nerve injury, and rotator cuff tear.
Figure 86: Total shoulder arthroplasty. The glenoid component is made of plastic and not readily apparent on x-ray (unless you look for it); it is outlined in the reproduction at right. (courtesy https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093753/)
Reverse Shoulder Arthroplasty
In a reverse shoulder arthroplasty, the glenoid socket is replaced with a metal ball and secured to the scapula and the humeral head is replaced with a cup attached to a stem which functions as a socket (
figure 9Figure 7). This is the opposite anatomic arrangement of the native glenohumeral joint. This arrangement provides stability in the absence of a functioning rotator cuff. It is indicated for rotator cuff arthropathy, severe proximal humerus fractures, failed total shoulder arthropathy, and glenohumeral deformities that cannot be reconstructed otherwise. This operation can dramatically increase the function of the shoulder and provide excellent pain relief.
figure 9 . Figure 7: A reverse shoulder arthroplasty
An arthrodesis involves the surgical resection and fusion of the glenohumeral joint.
The characteristic osteophyte of glenohumeral arthritis is termed a goat’s beard (
see figureFigure 108).
Figure 108: An inferior osteophyte suggestive of of a goat’s beard
Glenohumeral arthritis, Osteoarthritis, Rheumatoid arthritis, articular cartilage, Arthroplasty.