Glenohumeral Osteoarthritis
The diagnosis is glenohumeral osteoarthritis (shoulder osteoarthritis), characterized by degenerative joint disease with cartilage loss, joint space narrowing, and osteophyte formation at the inferior glenoid rim. 1
Diagnostic Features
The imaging findings you describe are pathognomonic for shoulder osteoarthritis:
- Joint space narrowing in the inferior glenohumeral joint represents progressive articular cartilage degeneration 1
- Inferior glenoid rim osteophyte is a characteristic structural change of degenerative joint disease, representing subchondral bone remodeling as the joint surface loses its sphericity and congruity 1, 2
- These radiographic findings (joint space narrowing and osteophyte formation) are the hallmark features used to diagnose shoulder osteoarthritis 1, 2
Clinical Context
Glenohumeral osteoarthritis typically presents with:
- Progressive shoulder pain that worsens with activity 1
- Loss of both active and passive range of motion due to joint capsule thickening and cartilage loss 1, 2
- Gradual onset in the aging population, representing a chronic degenerative process 1
Important Clinical Consideration
The inferior humeral head osteophyte warrants specific attention because it can cause axillary nerve entrapment, leading to teres minor muscle atrophy and contributing to pain beyond the primary osteoarthritis 3, 4. Studies demonstrate that inferior osteophytes correlate with increased fatty infiltration of the teres minor muscle (11.9% vs 4.4% without osteophyte, P=0.004), suggesting nerve compression 4. This represents a potentially treatable component of the patient's symptoms 4.
Differential Considerations to Exclude
While the diagnosis is osteoarthritis, consider:
- Haemochromatosis arthropathy if the patient is younger (typically affects 2nd and 3rd metacarpophalangeal joints primarily, but can involve other joints with exuberant osteophytes) 5
- Inflammatory arthropathies (though these typically lack prominent osteophyte formation and show different distribution patterns) 5
Diagnostic Confirmation
Plain radiographs showing joint space narrowing and osteophytes are sufficient for diagnosis 1, 2. MRI may be considered if evaluating for rotator cuff integrity or assessing for axillary nerve entrapment from the inferior osteophyte 2, 4.