Classes of criteria:
(1) patient reported findings, with >= 2 of the following:
(1a) pain (intensity, frequency, duration)
(1b) symptoms or signs
(1c) self-reported function
(1d knee-related quality of life
(2) clinical exam with at least one of the following:
(2a) joint line tenderness
(2b) crepitus
(3) knee radiographs show Kellgren and Lawrence grade 0 or 1 (over range from 0 to 4; no or possible joint narrowing, no or possible osteophytes, no sclerosis, no deformity)
The Knee Injury and Osteoarthritis Score (KOOS) is recommended as a patient questionnaire, with score <= 85% for a domain considered as meeting the criteria.
MRI of the knee is not recommended because:
(1) there are no validated consensus criteria for early osteoarthritis
(2) it detects structural joint changes in a large proportion of the society (sensitive but not specific)
