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Ahlbäck classification of knee osteoarthritis

Last revised by Dr Henry Knipe on 19 Apr 2020

The Ahlbäck classification is one of many ways to grade knee osteoarthritis.


  • grade 1: joint space narrowing (less than 3 mm)
  • grade 2: joint space obliteration
  • grade 3: minor bone attrition (0-5 mm)
  • grade 4: moderate bone attrition (5-10 mm)
  • grade 5: severe bone attrition (more than 10 mm)

History and etymology

This classification was proposed by Ahlback et al. in 1968.

See also

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Cases and figures

  • Case 1: grade 4 osteoarthritis
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