Glenohumeral arthritis is characterized by destruction of the articular cartilage of the glenohumeral joint. Etiologies of shoulder arthritis include osteoarthritis, inflammatory arthritis, rotator cuff arthropathy, postraumatic arthritis, and osteonecrosis.
The clinical presentation depends on the underlying cause of the arthritis.
Patients with GH 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 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.
Patients with rheumatoid arthritis present with pain, decreased ROM, crepitation, and effusions in multiple joints. The effects typically evolve slowly and insidiously. The shoulder is rarely the first joint affected and it is never the only affected joint.
In cuff tear arthropathy, patients are usually significantly disabled and are unable to raise their affected arm. Inspection may show hollowing around the scapula secondary to cuff muscle atrophy.
A number of other disease processes, including osteonecrosis, recurrent GH dislocations, and posttraumatic articular incongruity can lead to destruction of the GH articular cartilage. In most cases, this results in secondary osteoarthritis and has symptoms similar to primary osteoarthritis although the clinical course may be altered by the inciting process.
Although less common than hip and knee arthritis, osteoarthritis of the glenohumeral joint is thought to occur in up to 20% of adults.
More common in women and increasing age.
Only 5% of patients with shoulder pain have arthritis.
It is estimated that 1.5 million adults have rheumatoid arthritis. Glenohumeral joint involvement in patients with long-standing rheumatoid arthritis is 55%. Half of those develop severe destruction of the joint.
Only 4% of rotator cuff tears progress into rotator cuff arthropathy.
Pathology and pathophysiology
The pathogenesis of GH osteoarthritis is not clear. The pathognomic finding of osteoarthritis in the GH joint is the presence of osteophytes along the inferior margin of the humeral articular surface (“goats beard osteophyte”). These osteophytes increase the tension within the anterior joint capsule, leading to hypertrophy of the anterior capsule and a decrease in external rotation.
Rheumatoid arthritis is a systemic autoimmune disorder thought to be secondary to a combination of genetic and environmental factors. The cause of cartilage destruction in RA is secondary to a proliferative inflammatory process of the synovium. This inflammatory process affects the surrounding soft tissue and bone leading to attenuation and may rupture the rotator cuff, joint capsule, and the long head of the biceps.
Rotator cuff arthropathy starts with a failure of the rotator cuff causing diminished compressive forces of the humeral head into the glenoid. This allows superior humeral head migration leading it to articulate with the superior margin of the glenoid and the undersurface of the acromion which causing accelerated articular wear.
Osteonecrosis of the glenohumeral joint is a relatively uncommon process in which vascular compromise of the humeral head occurs leading to collapse, joint incongruity, and arthritis.
Rotator cuff Disease
Cervical spine disease
Rotator cuff arthropathy
Radiographic and laboratory findings
Radiographic workup begins with true AP (in plane with the scapula), scapular Y, and axillary views.
Osteoarthritis demonstrates humeral osteophytes, joint space narrowing, subchondral sclerosis, and subchondral cystic changes. Posterior glenoid bone loss is typical of osteoarthritis. Bone loss and posterior humeral suluxation are best seen on the axillary view.
Rheumatoid arthritis demonstrates concentric central glenoid wear, diffuse osteopenia, periarticular boney erosions, and subchondral cysts.
Rotator cuff arthropathy demonstrates superior humeral translation, osteophytes, joint space narrowing, rounding of the greater tuberosity, and superior glenoid wear.
CT scan is useful in assessing the glenoid bone stock prior to operative treatment.
Risk factors and prevention
Risk factors of osteoarthritis of the glenohumeral joint include previous shoulder surgery, history of shoulder trauma, and shoulder overuse.
Risk factors of rheumatoid arthritis are thought to include genetic factors and/or an infectious or environmental “triggers”.
Risk factors of osteonecrosis include chronic steroid use, alcoholism, sickle cell disease, caisson’s disease, hyperuricemia, Gaucher’s disease, pancreatitis, hyperlipidemia, lymphoma, and organ transplantation.
The treatment of arthritis depends on the patient’s discomfort and ability to function. Initially, conservative therapy should be attempted including activity modification, anti-inflammatory medications, steroid injections, or hyaluronic acid injections. Physical therapy may be useful in maintaining range of motion, but it can also aggravate symptoms.
As pain worsens and disability increases, surgical treatment is often needed. Total shoulder arthroplasty (TSA) is an excellent treatment for patients with an intact rotator cuff. TSA involves replacing the humeral head with a metal sphere and replacing the glenoid surface with a polyethylene disc.
Occasionally, the amount of posterior glenoid bone loss will preclude the placement of a glenoid component, in which case the glenoid can be reamed to create a smooth surface and a hemiarthroplasty can be placed. Hemiarthroplasty is also favored in patients under 40-50 years old with osteoarthritis.
In cuff tear arthropathy, glenoid replacement is contraindicated because the humeral head is no longer concentrically articulating with the glenoid. The patients are most commonly treated with a reverse shoulder arthroplasty. In this device, a sphere is place on the glenoid side of the articulation while the concave surface is placed on the humeral side.
Shoulder arthrodesis (fusion) is an alternative in patients with arthritis accompanied by muscle paralysis or severe infection, or for failed previous surgery.
Pain relief after a TSA is significant with 85-90% good to excellent results reported at 10-15 years.
Functional results of TSA for rheumatoid arthritis is inferior to TSA done for osteoarthritis because of the damage to the surround soft tissues.
Osteoarthritis of the GH joint is relatively protective of the rotator cuff, which is intact in 90% of these patients.
Glenohumeral arthritis, glenohumeral arthrosis, osteoarthritis, rheumatoid arthritis, osteonecrosis, cuff tear arthropathy, total shoulder arthroplasty, shoulder hemiarthroplasty, reverse shoulder arthroplasty, posttraumatic arthritis.
Lehtinen JT, Kaarela K, Belt EA, Kautiainen HJ, Kauppi MJ, Lehto MU. Incidence of glenohumeral joint involvement in seropositive rheumatoid arthritis: a 15 year endpoint study. J Rheumatol 2000;27:347--50.
Orthopaedic Surgery: Principles of Diagnosis and Treatment. Brent B Wiesel et al. p 542-546. Lippincott Williams & Wilkens. 2011.