Fig. 1

Pulsed radiofrequency (PRF) alleviated symptoms of knee pain in mouse models. (a) Animal experimental schedule. The knee pain mouse models were established by a joint injection of MIA in saline (red arrow). The behavioral tests were performed on days 0, 1, 3, 7, 10, and 14 (yellow arrows). PRF or sham operation was performed on day 7 (left arrow). Tissue collection was done on day 14 (right arrow). (b) Representative photos during PRF (left: catheterized procedures for PRF or sham operation, right: grounding of the catheter tip and sciatic nerve). Red line: catheter needle; Yellow arrow: sciatic nerve. (c) Representative photos during the weight-bearing test. (d) Representative photograph during the foot stamp test. (e) The bar graphs of the average value of the weight-bearing test at 0, 1, 3, 7, 10, and 14 days. White: Sham and Grey: PRF group. Normal: 0 day, knee pain (pre-PRF): 1, 3, 7 days, and knee pain (post PRF): 10, 14 days. Data are presented as mean ± SD. Statistical analysis was performed using one-way repeated-measures ANOVA within each group to evaluate time-dependent changes, and unpaired t-tests were used to compare PRF and Sham groups at each time point. ^†p < 0.05 vs. 0 day in the sham group, ^♭p < 0.05 vs. 0 day in the PRF group normal, *p < 0.05, **p < 0.01 vs. the sham group on the same day. (f) The bar graphs of the average value of the foot stamp test at 0, 1, 3, 7, 10, and 14 days. White: Sham and Grey: PRF group. Normal: 0 day, knee pain (pre-PRF): 1, 3, 7 days, and knee pain (post-PRF): 10, 14 days. Data are presented as mean ± SD. Statistical analysis was performed using one-way repeated-measures ANOVA within each group to evaluate time-dependent changes, and unpaired t-tests were used to compare PRF and Sham groups at each time point. ^†p < 0.05 vs. 0 day in sham group, ^♭p < 0.05 vs. 0 day in the PRF group normal, *p < 0.05, **p < 0.01 vs. the sham group on the same day. (g) Representative photomicrograph of safranin O staining in the knee joint (top left: sham; top right: PRF; bottom: contralateral). Black arrows: knee cartilage. Scale bar: 50 μm. (h) The bar graphs of the average value of the Mankin score. White: Sham and Grey: PRF group.