Kellgren and Lawrence system for classification of osteoarthritis of knee

The Kellgren and Lawrence system is a common method of classifying the severity of knee osteoarthritis (OA) using five grades 1. This classification was proposed by Kellgren et al. in 1957 2 and later accepted by WHO in 1961.

In applying the system, the prevalence of chronic knee pain in a postal survey of 2000 swedes aged 35-54 was 15%1. Of these respondents, 1% showed radiographic knee OA, based on bilateral weight bearing plain films1.


  • grade 0: no radiographic features of OA are present
  • grade 1: doubtful joint space narrowing (JSN) and possible osteophytic lipping
  • grade 2: definite osteophytes and possible JSN on anteroposterior weight-bearing radiograph
  • grade 3: multiple osteophytes, definite JSN, sclerosis, possible bony deformity
  • grade 4: large osteophytes, marked JSN, severe sclerosis and definite bony deformity
Knee pathology

The knee is a complex synovial joint that can be affected by a range of pathologies:

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Article information

rID: 27111
Synonyms or Alternate Spellings:
  • Kellgren & Lawrence system for classification of osteoarthritis of knee
  • Kellgren & Lawrence system for classification of osteoarthritis in the knee

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Cases and figures

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    Case 1: grade IV osteoarthritis
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