Table 1 Comparison of Kellgren and Lawrence criteria for grading the severity of knee osteoarthritis in the standing anteroposterior radiograph and alternative criteria based on semi‐quantitative ratings of the severity of osteophytosis and joint space narrowing in the semiflexed anteroposterior view.

Grade	Kellgren and Lawrence criteria13		Alternative criteria
			Severity of osteophytosis*	Severity of JSN*
0	No features of OA		0	0
1	Minute osteophyte, doubtful significance		0	0
2	Definite osteophyte, unimpaired joint space		⩾1	0
3	Definite osteophyte and moderate diminution of joint space		⩾1	1 or 2
4	Definite osteophyte and joint space greatly narrowed, and sclerosis of subchondral bone		⩾1	3

JSN, joint space narrowing; OA, osteoarthritis.

*Consensus ratings based on Osteoarthritis Research Society International atlas.²⁴