Table 1.

American Rheumatism Association (ARA) criteria for the classification of knee OA

Numerical order	Clinical characteristics
1	Knee joint ache most of the time before onset of knee OA
2	Clicking of joint
3	Morning stiffness for less than 30 min
4	Over 40 years old
5	Swollen knee joint; clicking of joint
6	Swollen knee joint; without clicking of joint

In clinical criteria, knee OA was diagnosed if the patient met the criteria of 1 + 2 + 3 + 4, 1 + 2 + 3 + 5, or 1 + 6

OA osteoarthritis