Eighty-nine patients with knee osteoarthritis were randomized into 4 groups to receive 4 sessions of weekly radial extracorporeal shock wave (rEWST) therapy with lower or higher density and shock numbers: LD/2,000 (n=19), LD/4,000 (n=19), HD/2,000 (n=19) and HD/4,000 (n=18) or control (n=14). The primary outcome of interest was pain evaluated using a visual analogue scale (VAS). The secondary outcome of interest was function evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. All outcomes were measured after each of the 4 sessions, and at 4-weeks post-treatment. Results of this study demonstrated that across all timepoints, varying the intensity had a statistically significant effect on VAS pain score as well as an interaction effect between intensity and time (p<0.001 for both). Varying the intensity and shock number also had a statistically significant effect on WOMAC physical function scores (p<0.05). In addition, an interaction effect between intensity and time as well as number and time were observed (p<0.05). At 4 weeks follow-up, mean VAS pain scores in the HD rESWT groups were statistically significantly lower compared to both the LD and control (p<0.001 for all). No statistical significant difference was observed when comparing the 2,000 rESWT group to the 4,000 rESWT group (p>0.99), however, the mean VAS pain scores in the 2,000 impulses rESWT and 4,000 rESWT groups were statistically significantly lower when compared to the control (p<0.011 for both). For WOMAC physical function scores, both HD and LD rESWT scores were statistically significantly lower when compared to control (p<0.001 for both). However, no statistical significant difference was observed when comparing LD and HD rESWT WOMAC physical function scores (p=0.05).Mean WOMAC physical function scores in the 4,000 rESWT group were statistically significantly lower compared to control (p<0.001) and to the 2,000 rESWT group (p=0.022).