Background The painful shoulder is, concerning the frequency, the third reason for consultation in primary care. A recent review of epidemiological studies estimated incidence among 9–25 cases per 1000 habitants/year, the prevalence/point between 69 to 260 per 1000 habitants and prevalence/year between 47–467 cases per 1000 habitants. These numbers vary according to age groups, the study methodology, the diagnostic criteria used and countries. In Spain they have been reported prevalences/point of 78 per 1000 habitants and review studies relate variations in prevalence between 70–200 per 1000 adults. Only 40%–50% of those affected consultation by pain, and of these, in half the symptoms persist one year after the first consultation, which involves a significant consumption of healthcare resources production losses and employee absenteeism.

Methods A clinical trial not randomised, which found the effect of a unique setting with activator and with address craneo-caudal, on the highest part of humeral head, evaluated by ultrasound, using for this purpose the M-Mode setting with a M7 Mindray (Shenzshen Mindray Co. Ltd, China) ultrasound unit and linear probe (50 mm footprint). The following variables were studied: pain, using the visual analogue scale (VAS), subacromial space (cm) before and after the adjustment, displacement (cm), speed (cm/s) and time (ms) displacement of the humeral head.

Results Baseline characteristics of both groups were similar (1? and 4?, mean age (years) 40.6±6, 23, weight (kg) 70,60±12,7, height (m) 1,69±0,11, a BMI with 24,52±2,88 (60% with normal weight and 40% overweight), the affected side was the right to the left el 40% and 60%, and a VAS 7,2±1,3). The means of displacement of the subacromial space pre-intervention 1,19±0,29 mm and post 1,23±0,3 mm by performing a t-Student test where found no statistically significant difference (t 2,51; p<0,01). In speed were 1,08±0,12 cm/s, distance of 0,09±0,02 cm in a time of 86,40±14,31 ms.

Conclusions Once the relevant statistical analysis was made, it was concluded that the activator is an effective technique to increase the subacromial space in the short term, where there were statistically significant differences (t 2,51; p<0,01). Still need future studies that demonstrate that the effect stays in time with a larger sample size and comparator group.