Objective: To evaluate the efficacy of topical vibratory stimulation for reducing pain during trigger point injection (TPI).
Design: Double-blind randomized placebo-controlled clinical trial.
Setting: Tertiary care university hospital.
Participants: A total of 136 participants were randomly recruited from among patients with myofascial pain syndrome who were scheduled for TPI. Of these, 65 were excluded because they met the exclusion criteria, and 11 because they refused to participate. Finally, 60 participants were enrolled. No participants dropped out of the study.
Intervention: Participants were randomly assigned to the vibration group or control group. TPI was performed with 0.5% lidocaine using a 25-gauged needle. A vibrator was applied to the popliteal fossa for 3–5 seconds prior to and during TPI to the gastrocnemius; 100 Hz vibration was turned on for the vibration group and turned off for the control group. 
Main Outcome Measures: Pain intensity during TPI was assessed using a 100-mm visual analog scale (VAS) as a primary outcome, and participant satisfaction and preference for repeated use were measured using five-point Likert scales as a secondary outcome. These parameters were evaluated immediately after TPI. The primary outcome was evaluated using analysis of covariance (ANCOVA) and secondary outcome using the Mann–Whitney U-test.
Results: VAS scores for pain during TPI were significantly lower in the vibration group (30.30; 95% confidence interval [CI]; 22.65–39.26) compared with the control group (47.58; 95% CI; 38.80–56.52; F = 7.74; P < 0.01). The mean difference in VAS scores between the two groups was 17.27 (95% CI: 5.24–29.30). Participant satisfaction and preference for repeated use were significantly higher in the vibration group than in the control group (P < 0.05). No participant showed any side effects.
Conclusions: Topical vibratory stimulation significantly decreased pain during TPI of the gastrocnemius.

EFFICACY OF TOPICAL VIBRATORY STIMULATION FOR REDUCING PAIN DURING TRIGGER POINT INJECTION TO THE GASTROCNEMIUS: A RANDOMIZED CONTROLLED TRIAL