Cryotherapy decreases synovial Doppler activity and pain in knee arthritis: A randomized-controlled trial

To measure and compare the effects of 2 local cryotherapy techniques on synovial power Doppler activity (primary outcome) and pain in non-septic knee arthritis without any concurrent treatment.

30 patients were randomized (ice: 30min, n=15 or cold CO₂: 2min, n=15 both applied twice at 8h interval). Contralateral non-treated arthritic knees were used as paired controls (n=11 and n=10 respectively). The PDUS semi-quantitative score (0-3) and pain visual analogic scale were evaluated before/after each cold application, 2min, 2h, 24h after the first application. PDUS scores were checked in double-blind by 2 ultrasonographists.

The inter-class effect size of local cryotherapy on the power Doppler score remained significant the day after treatment in local cryotherapy-treated compared to contralateral non-treated knees (Global difference: -1 [95% confidence interval: -1.23; -0.77]; ice: -0.73 [-1.06; -0.4]; CO₂: -0.7 [-1.18; -0.22]). Both techniques significantly and to the same extent reduced the power Doppler score and pain visual analogic scale at all evaluation times and globally throughout the 24 hour-study period. No dropout nor adverse event was reported. In multivariate analysis, the Power Doppler score decrease was associated with pain decrease, while pain decrease was associated with the female sex and ice technique.

Local ice and cold CO₂ applied twice equally reduced synovial Power Doppler activity and pain over 24h in knee arthritis. These effects remained significant the day after treatment. ClinicalTrials.gov identifier: NCT02573298.