Table 1.

Levels of radiographic knee osteoarthritis according to the Kellgren and Lawrence scale

Stage	Kellgren & Lawrence criteria	Ex-elite table tennis players (n = 22)	Control subjects (n = 22)
0	Normal	5 (22.7%)	14 (63.7%)
1	Doubtful narrowing of joint space and possible osteophytic lipping	5 (22.7%)	7 (31.7%)
2	Definite osteophytes and possible narrowing of JS	6 (27.3%)	1 (4.5%)
3	Moderate multiple osteophytes, definite narrowing of JS, some sclerosis and possible deformity of bone contour	5 (22.7%)	0
4	Large osteophytes, marked narrowing of JS, severe sclerosis, and definite deformity of bone contour	1 (4.6%)	0

JS = joint space