Table 1.

Study website questionnaires.

Questionnaires	Baseline	Control-period	Case-period
Demographics	x
Comorbidities	x
Perceived risk factors	x
Baseline pain characterization -Index knee	x
Baseline pain characterization -Contralateral knee	x
Medications	x	x	x
Lubben social support	x	x	x
Knee injury and Osteoarthritis Outcome Score (KOOS) - Index knee	x	x	x
Knee Injury and Osteoarthritis Outcome Score (KOOS) - Contralateral knee	x	x	x
Intermittent and Constant Osteoarthritis Pain (ICOAP)	x	x	x
Physical activity	x	x	x
Footwear change and heel height	x	x	x
Trauma/injury/knee buckling	x	x	x
Climate	x	x	x
Pain Coping Inventory (PCI)	x	x	x
Perceived Stress Scale (PSS-10)	x	x	x
Daily mood measured by using Positive and Negative Affect Scale (PANAS)	x	x	x
Pain flare			x