The Outerbridge classification is used to grade articular cartilage damage during arthroscopy. Grade IV is defined as:

• A Softening and blistering of the cartilage surface
• B Fragmentation and fissuring in an area of <1.3 cm diameter
• C Fragmentation and fissuring in an area of >1.3 cm diameter
• D Full-thickness cartilage loss exposing subchondral bone ✓

Explanation

Outerbridge classification: Grade I = cartilage softening/blistering (no surface break); Grade II = partial thickness fissuring/fragmentation <1.3 cm; Grade III = partial thickness fissuring/fragmentation >1.3 cm; Grade IV = full-thickness cartilage loss with exposed subchondral bone. Grade IV corresponds to bone-on-bone arthritis visible arthroscopically and predicts poorer outcomes from non-arthroplasty procedures. It guides the threshold for microfracture, osteochondral autograft, or arthroplasty.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.