Kellgren-Lawrence Classification

Written by Dr Sheila Strover on March 14, 2025

The Kellgren-Lawrence Classification is an X-ray classification scheme for osteoarthritis of the knee.

Kellgren-Lawrence classification of OA

The classification is as follows:

  • Grade 1 - doubtful narrowing of the joint space with possible osteophyte formation
  • Grade 2 - possible narrowing of the joint space with definite osteophyte formation
  • Grade 3 - definite narrowing of joint space, moderate osteophyte formation, some sclerosis, and possible deformity of bony ends
  • Grade 4 - large osteophyte formation, severe narrowing of the joint space with marked sclerosis, and definite deformity of bone ends

Reference

Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis. 1957;16(4):494–502.