Modified Outerbridge grading of chondromalacia

Last revised by Henry Knipe on 26 Aug 2019

The modified Outerbridge grading of chondromalacia is divided into four grades by MRI, typically using fat-saturated proton density sequences. This grading system was originally devised for arthroscopy initially for assessment of chondromalacia patellae, but then modified and extended for all chondral surfaces 1:

  • grade I
    • focal areas of hyperintensity with normal contour 
    • arthroscopically: softening or swelling of cartilage
  • grade II
    • blister-like swelling/fraying of articular cartilage extending to surface
    • arthroscopically: fragmentation and fissuring within soft areas of articular cartilage
  • grade III
    • partial-thickness cartilage loss with focal ulceration
    • arthroscopically: partial thickness cartilage loss with fibrillation (crab-meat appearance)
  • grade IV
    • full-thickness cartilage loss with underlying bone reactive changes
    • arthroscopically: cartilage destruction with exposed subchondral bone

This is not to be confused with the osteochondral injury staging system or osteochondritis dissecans surgical staging system.

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