Sample size
Pain, KOA
OSTEOARTHRITIS
There are no previous studies on the trigger point compared with oral diclofenac for KOA. For this reason, we did not use data from the literature to calculate the sample size. Based on previous pilot trials, the primary outcome measures Numeric Pain Rating Scale (NPRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used to estimate the sample size, assuming an effect size of 0.4, using G Power 3.1.9.4, assuming a two-tailed test, an alpha level (α) of 0.05, and a desired power (β) of 90%. The estimated desired sample size was calculated to be at least 34 subjects per group. To compensate for a 20% drop-out rate, the sample size was increased to 41 patients in each group.