47 patients with non-septic knee arthritis were treated by local ice (30 min) or cold CO2 (2
min) twice at an 8 hour-interval for 1 day.

The synovial fluid was collected just before the first cold application then 24 hours later.

Cytokine, VEGF, NF-kB, PG-E2 levels were assessed in the synovial fluid before/after
treatment.

Contralateral arthritic knees were used as paired controls when possible.