Grades of osteoarthritis by Ahlbäck

Grading of joint osteoarthritis by Ahlbäck uses plain postero-anterior weight-bearing radiographs to assess the extent of degenerative disease as joint space narrowing and bone attrition.

Grade - Changes Description
Grade I joint space narrowing (<3mm)
Grade II joint space obliteration
Grade III minor bone attrition (0 - 5mm)
Grade IV moderate bone attrition (5 - 10mm)
Grade IV severe bone attrition (>10mm)

References

1. Ahlbäck S. Osteoarthrosis of the knee: a radiographic investigation. Acta Radiol Stockholm 1968; (suppl 277):7-72.
2. Petersson IF, Boegård T, Saxne T, Silman AJ, Svensson B. Radiographic osteoarthritis of the knee classified by the Ahlbäck and Kellgren & Lawrence systems for the tibiofemoral joint in people aged 35-54 years with chronic knee pain. Ann Rheum Dis. 1997 Aug;56(8):493–6

3. Hernández-Vaquero D, Fernández-Carreira JM. Relationship between radiological grading and clinical status in knee osteoarthritis. a multicentric study. BMC Musculoskeletal Disorders. 2012 Oct 9;13(1):194
4. Davies AP, Calder DA, Marshall T, Glasgow MM. Plain radiography in the degenerate knee. A case for change. J Bone Joint Surg Br. 1999 Jul;81(4):632–5.