Osteoarthritis (Knee OA)

🔍 When to Suspect

A patient aged 45 or over presents with activity-related knee pain and no morning stiffness, or stiffness that lasts less than 30 minutes

From the full topic in The Ocean Library: Osteoarthritis (Knee OA)

🧭 When to suspect

Osteoarthritis (OA) is the most common form of arthritis, and the knee is one of the most frequently affected joints.

• It is a leading cause of pain and disability in older adults, and is overwhelmingly managed in primary care.

• It is a whole-joint "wear and repair" process involving cartilage loss, bony remodelling and low-grade synovial change.

• The degree of damage on X-ray correlates poorly with how much pain a person has.

The diagnosis is clinical. Under NICE NG226, diagnose knee osteoarthritis without imaging in a person who:

• Is 45 or over

• Has activity-related joint pain

• Has either no morning joint-related stiffness or morning stiffness lasting no longer than 30 minutes

Imaging is not needed to confirm the diagnosis and should be reserved for atypical features.

Clinically:

• Recognise the mechanical pattern (pain worse with use, eased by rest)

• Never miss an inflammatory or septic mimic

Raise suspicion in those with:

• Increasing age

• Overweight or obesity (the main modifiable risk factor)

• Previous joint injury or surgery (e.g. meniscectomy, anterior cruciate ligament rupture)

• Occupations involving heavy lifting or repetitive kneeling/squatting

• A family history of OA

• Women, in whom knee OA is more common

Points towards osteoarthritis
• Age ≥ 45 with gradual-onset, activity-related pain (worse with use, better with rest)
• No morning stiffness, or stiffness ≤ 30 minutes
• Crepitus, bony swelling and restricted movement
• Functional limitation (stairs, walking, kneeling) without systemic illness

Atypical features – reconsider the diagnosis
• Hot, red, swollen, acutely painful joint – think septic or crystal arthritis
• Prolonged morning stiffness > 30 minutes, or pain worse at rest and easing with movement – think inflammatory arthritis
• Rapidly worsening pain, function or deformity, or marked systemic upset
• Rest/night pain with weight loss or a history of cancer (bone pathology), or true locking (meniscal tear or loose body)

Source: NICE NG226

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