Table 1 American College of Rheumatology Criteria for classification of hip and knee idiopathic osteoarthritis.22 23

Knee	Hip
Clinical and radiographic knee pain	Combined clinical and radiographic hip pain
and at least 1 of 3:	and
Age >50 years	Femoral and/or acetabular osteophytes on radiograph
Stiffness <30 minutes	Or
Crepitus	ESR ⩽20 mm/1st h
and	and
Osteophytes	Axial joint space narrowing on radiograph