Effects of Long Duration Low Intensity Ultrasound for Active Trapezius Trigger Points: A Randomized Clinical Trial.

CONTEXT: Upper trapezius trigger points can be debilitating and often lead to chronic pain.

OBJECTIVE: To determine if long duration low intensity therapeutic ultrasound is effective at treating upper trapezius trigger point pain compared to an inactive placebo treatment.

DESIGN: Randomized control trial.

SETTING: Research laboratory.

PATIENTS OR OTHER PARTICIPANTS: Fifty-one participants (19 males, 32 females, age = 31.8 ± 12.5 y, ht = 168.6 ± 15.9 cm, mass = 77.1 ± 16.1 kg) diagnosed with chronic upper trapezius pain.

INTERVENTIONS: Participants were randomly assigned into an active (n = 32) or sham (n = 19) treatment group. Treatments were applied at least 3 times a week for 4 weeks and each ultrasound treatment lasted 4 h.

MAIN OUTCOME MEASURES: Participants completed a daily numeric rating scale (NRS) pain diary. Pain pressure threshold was assessed via a pressure algometer. Repeated-measures ANCOVAs were used to examine differences over time and between groups.

RESULTS: Pain on the NRS was significantly reduced from baseline (5.4 ± 1.7) to the conclusion of the study (4.2 ± 1.6) (F4,254 = 7.747, P < 0.001); however, the reduction did not significantly differ between the two groups (F4,254 = 1.096, P = 0.359). There was an average reduction in pain of 1.1 ± 1.8 points over the course of a 4 h treatment (F4,254 = 18.67, P = 0.001), but this reduction did not differ between groups, (F4,254 = 0.701, P = 0.592). Pain pressure threshold improved by 0.46 ± 1.29 and 0.44 ± 1.73 kg for active and sham groups, respectively, but was not different between groups (F2,142 = 1.168, P = 0.314).

CONCLUSIONS: Four-weeks of low intensity long duration ultrasound reduced upper trapezius trigger point pain, but the improvement is attributed to a placebo effect.