Ahlbäck classification of knee osteoarthritis

Last revised by Henry Knipe on 23 Feb 2024

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


The Ahlbäck classification is in common use (c. 2012) in both clinical and research settings 2.


  • grade 1: joint space narrowing (<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 (>10 mm)

History and etymology

This classification was proposed by Ahlbäck et al. in 1968 3.

See also

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