Kellgren and Lawrence system for classification of osteoarthritis

Last revised by Henry Knipe on 15 Sep 2021

The Kellgren and Lawrence system is a common method of classifying the severity of osteoarthritis (OA) using five grades. 

The original paper 1 graded OA at the following sites and projections:

  • hands: posteroanterior
  • cervical spine: lateral
  • lumbar spine (facet joints only): lateral
  • hips: anteroposterior
  • knees: anteroposterior
  • feet: anteroposterior


Numerous variations of the Kellgren and Lawrence classification system have been used in research 3. Below is the original description 1-3:

  • grade 0 (none): definite absence of x-ray changes of osteoarthritis
  • grade 1 (doubtful): doubtful joint space narrowing and possible osteophytic lipping
  • grade 2 (minimal): definite osteophytes and possible joint space narrowing
  • grade 3 (moderate): moderate multiple osteophytes, definite narrowing of joint space and some sclerosis and possible deformity of bone ends
  • grade 4 (severe): large osteophytes, marked narrowing of joint space, severe sclerosis and definite deformity of bone ends

Osteoarthritis is deemed present at grade 2 although of minimal severity 1

History and etymology

This classification was proposed by Kellgren and Lawrence in 1957 1 and later accepted by the World Health Organisation (WHO) in 1961 as the radiological definition of OA for the purpose of epidemiological studies 3,4.

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Cases and figures

  • Case 1: grade IV osteoarthritis
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  • Case 2: grade III
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