Kellgren and Lawrence Grade 4 osteoarthritis on a knee X-ray is characterised by:

• A Doubtful joint space narrowing with a possible osteophyte
• B Definite osteophytes with normal joint space
• C Joint space narrowing (<50%), multiple osteophytes, subchondral sclerosis and cysts
• D Gross joint space loss with bone-on-bone contact, large osteophytes, severe subchondral sclerosis and deformity ✓

Explanation

Kellgren-Lawrence grading of OA: Grade 0 = no features; Grade 1 = doubtful narrowing, minimal osteophyte; Grade 2 = definite osteophytes, doubtful narrowing; Grade 3 = moderate narrowing, multiple osteophytes, sclerosis, possible deformity; Grade 4 = severe narrowing (bone-on-bone), large osteophytes, severe sclerosis and deformity. Grade 4 is the radiological indication for joint replacement surgery when symptoms are refractory to conservative management.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.