Objective: To determine whether 448 kHz capacitive-resistive monopolar radiofrequency (CRMR) after platelet-rich-plasma (PRP) injections can further reduce pain sensation within the first 72 h in an active population with patellar chondropathy. Methods: One-hundred fifty-three active patients with patellar chondropathy grade II-III were followed for three days after PRP injections with and without CRMR under a control-placebo study. They were clinically evaluated for pain sensation using a visual analog scale ranging from zero (no pain sensation) to ten (highest pain sensation). Pain sensation was described using medians and analyzed through the Friedman and Conover test for within-group comparison (pre-intervention, and 24, 48, and 72 h post-intervention) and the Mann-Whitney test for between-group comparisons (Intervention vs. Placebo) with α = 5% and 1-β = 80%. Results: The placebo group showed statistical significance between pre-intervention and 24 h (Δ = -2.0 pts, p < 0.001), baseline and 48 h (Δ = -2.0 pts, p < 0.001), baseline and 72 h (Δ = -3.0 pts, p < 0.001), 24 h and 48 h (Δ = 0.0 pts, p < 0.016), and 24 h and 72 h (Δ = -1.0 pts, p < 0.001). The radiofrequency group showed statistical significance between baseline and 24 h (Δ = -7.0 pts, p < 0.001), baseline and 48 h (Δ = -7.0 pts, p < 0.001), baseline and 72 h (Δ = -8.0 pts, p < 0.001), 24 h and 72 h (Δ = -1.0 pts, p < 0.001), and 48 h and 72 h (Δ = -1.0 pts, p < 0.001). The placebo and radiofrequency groups were significantly different at 24 h (Δ = 4.0 pts, p < 0.001), 48 h (Δ = 4.0 pts, p < 0.001), and 72 h (Δ = 4.0 pts, p < 0.001). Conclusions: CRMR therapy administered after knee intra-articular injections of PRP within the first 72 h in active populations with patellar chondropathy reduces pain sensation with a median difference of 8.0 pts compared to baseline and 4.0 pts compared to placebo group.
Keywords: anterior knee pain; electrotherapy; high frequency; knee; patella; physical agents.