The baseline mean ( SD ) physical function score for the active group was 32.3 ( 9.2 ) and the week-13 score was 27.5 ( 12.9 ) units , whereas the baseline score for the sham treatment group was 32.4 ( 8.4 ) units and the week-13 score was 26.4 ( 11.3 ) units , for a mean difference of 1.4 units favoring sham ( 95 % CI , -3.8 to 6.5 ) at week 13 .