Table 1

Different descriptions of the classification criteria of Kellgren and Lawrence used in various epidemiological studies

Definition gradesOriginalAlternative 1Alternative 2Alternative 3Alternative 4
Grade 0: No osteoarthritisNo osteoarthritisNo osteoarthritisNo osteoarthritisNo osteoarthritisNo osteoarthritis
Grade 1: DoubtfulDoubtful narrowing of joint space and possible osteophytic lippingPossible osteophytesMinute osteophyte, doubtful significancePossible osteophytes onlyPossible osteophytic lipping
Grade 2: MildDefinite osteophytes and possible narrowing of joint spaceDefinite osteophytesDefinite osteophytes, unimpaired joint spaceDefinite osteophytes and possible JSNDefinite osteophytes and possible JSN
Grade 3: ModerateMultiple osteophytes, definite narrowing of joint space and some sclerosis and possible deformity of bone endsOsteophytes and JSNModerate diminution of joint space (with osteophyte)Moderate osteophytes and/or definite narrowingModerate multiple osteophytes, definite JSN, some sclerosis and possible bone contour deformity (bony attrition)
Grade 4: SevereLarge osteophyte, marked narrowing of joint space, severe sclerosis and definite deformity of bone endsLarge osteophytes, marked narrowing of joint space and definite deformityJoint space greatly impaired with sclerosis of subchondral boneLarge osteophytes, severe JSN and/or bony sclerosisLarge osteophytes, marked JSN, severe sclerosis and definite bony contour deformity (bony attrition)
  • JSN, joint space narrowing.