Modified Outerbridge grading of chondromalacia

Last revised by Dr 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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Cases and figures

  • Figure 1: normal
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  • Figure 2: grade 1
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  • Figure 3: grade 2
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  • Figure 4: grade 3
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  • Figure 5: grade 4
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  • Case 1: grade III
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  • Case 2: grade IV
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