Table 1.

Classification of osteoarthritis of the hip into four radiographic stages according to Toennis [16]

Grade 0	Grade I	Grade II	Grade III
No signs of osteoarthritis	Increased sclerosis of the head and acetabulum, slight narrowing of the joint space, slight lipping at the joint margins	Small cysts in the head or acetabulum, increasing narrowing of the joint space, moderate loss of sphericity of the head	Large cysts in the head or acetabulum, severe narrowing or obliteration of the joint space, severe deformity of the head and necrosis