Table 1.

Kellgren-Lawrence and Tönnis grading systems

Grade	Kellgren-Lawrence	Tönnis
0		No sign of osteoarthritis
1	Doubtful narrowing of joint space and possible osteophytic lipping	Increased sclerosis of the head and acetabulum, slight narrowing of the joint space, and slight lipping at the joint margins
2	Definite osteophytes and possible narrowing of joint space	Small cysts in the head or acetabulum, increasing narrowing of the joint space, and moderate loss of sphericity of the head
3	Moderate multiple osteophytes, definite narrowing of joint space, some sclerosis, and possible deformity of bone contour	Large cysts in the head or acetabulum, severe narrowing or obliteration of the joint space, severe deformity of the head, and necrosis
4	Large osteophytes, marked narrowing of joint space, severe sclerosis, and definite deformity of bone contour