We designed the study to detect a between-group difference of 1 point in pain intensity measured by the pain NRS, with an estimated standard deviation of 1.84 points, and a between-group difference of 4 points for disability measured by the RMDQ, with an estimated standard deviation of 4.9 points. The specifications were: power of 80%, an alpha coefficient of .05, and a possible loss to follow-up of up to 15%. Therefore, a total of 148 patients (74 patients per group) were recruited for our study. The estimates used in our sample size calculation were
lower than those suggested as the minimal clinically important difference (ie, 20% improvement for pain61 and disability62) in order to increase the precision of the effects of the interventions. A higher between-group difference would dramatically reduce our sample size,63 and this was one of the major limitations in previous trials.64,