A 77-year-old man presents to his GP complaining of right hip pain. This has been gradually getting worse over the last two years is worsened by movement. He is stiff for around 20 minutes in the morning. On examination, he has a large body habitus and has pain upon internal rotation of the right hip.

What is the most likely diagnosis?

Options:
explanation: Osteoarthritis is a degenerative arthritis caused by wearing of the articular cartilage. Risk factors include old age and obesity. It typically presents with a long gradual onset of pain and stiffness in affected joints. Distribution can be asymmetrical or symmetrical. Examination findings include reduced range of motion, swelling and crepitus. In the hip, internal rotation is often the first movement to become painful. According to NICE, the diagnosis is confirmed in a patient with all of the following:

- ≥45 years old
- Activity related joint pain
- No morning stiffness / <30 minutes of morning stiffness

This patient meets these criteria and, as such, can be diagnosed with osteoarthritis. Initial management for osteoarthritis includes conservative (weight loss, exercise) and medical (first line: paracetamol) measures, with surgery considered later in disease (arthroplasty)
name: Osteoarthritis
label: a
answer: yes
explanation: Ankylosing spondylitis is a HLA-B27 associated inflammatory arthritis. It presents with inflammatory joint pain and >30 minutes of morning stiffness. Symptoms are improved by exercise and worsened by rest. In addition, it is an axial spondyloarthropathy. This means it typically affects the spine, with other features including sacroiliac pain. In this case, there is no back pain. This makes ankylosing spondylitis much less likely
name: Ankylosing spondylitis
label: e
answer: no
explanation: Rheumatoid arthritis is an inflammatory arthritis. It presents with inflammatory joint pain, with >30 minutes of morning stiffness. Pain and stiffness tend to be improved by exercise and worsened by rest. In addition, although rheumatoid arthritis can affect the hip, it is a less likely site to be affected. More typical sites for early rheumatoid arthritis include the hands, feet and wrists
name: Rheumatoid arthritis
label: b
answer: no
explanation: Septic arthritis describes an infection of a joint, which can be life-threatening. Septic arthritis typically presents with pain and swelling over hours to days. There are also no other systemic features like fever or sepsis, which may be present with septic arthritis (although their absence does not rule out septic arthritis)
name: Septic arthritis
label: c
answer: no
explanation: Systemic lupus erythematosus (SLE) is a connective tissue disease that presents with inflammatory arthritis. It presents with inflammatory joint pain, >30 minutes of morning stiffness and pain and stiffness is improved by exercise and worsened by rest. In addition, there are often other extra-articular features in SLE, including fatigue, fever, weight loss, alopecia, malar rash, pericarditis, pleural effusion, blood abnormalities, and neurological involvement. There is also an association with antiphospholipid syndrome. None of these features are present in this case, making a diagnosis of SLE less likely
name: Systemic lupus erythematosus
label: d
answer: no

Correct answer: a