A 60-year-old man with a history of osteoarthritis in multiple joints presents with shoulder pain that worsens with movement. He denies any trauma or recent strenuous activity. What could be the likely diagnosis and how can it be confirmed?
Given the patient's history of osteoarthritis and his age, the likely diagnosis is osteoarthritis of the shoulder, also known as glenohumeral arthritis. This can be confirmed with a clinical examination and imaging studies such as an X-ray, which may show joint space narrowing, osteophytes, and subchondral sclerosis.