Development of a sham comparator for thoracic spinal manipulative therapy for use with shoulder disorders

Prior studies indicate thoracic spinal manipulative therapy (SMT) improves shoulder pain and disability. However, these studies are limited by no control or sham-treatment group. A valid sham comparator for thoracic SMT is needed. Subjects (n = 69) without shoulder pain were randomized to one of three groups: thoracic SMT, sham-SMT, or sham-ultrasound; and told they were randomized to manual therapy, range of motion, or ultrasound respectively. Perceived effects of the treatment on shoulder motion, pain, and functional were questioned before and after treatment. Believability was assessed by asking if the subject believed they received the active or inactive intervention. Shoulder active range of motion (AROM) was measured with a digital inclinometer before and after treatment by a blinded examiner. Believability of treatment was not significantly different between the SMT and sham-SMT (p = 0.12), but a greater proportion (p = 0.03) believed they received the active treatment in the SMT group (78.3%) as compared to the sham-ultrasound (47.8%). No differences in perception of treatment effects between the treatment groups were detected (p ≥ 0.1). Shoulder internal rotation AROM increased in the thoracic SMT group (mean difference = 3.7°; p = 0.006), but did not change within the sham-SMT (p = 0.44) or sham-ultrasound (p = 0.18) groups. Shoulder flexion did not change within any group. These preliminary results indicate the sham-SMT is an adequate sham comparator for SMT with similar expectations and believability as SMT active treatment. The sham-SMT had an inert effect on shoulder AROM. Sham-ultrasound was not believable as an active treatment. Future studies need to validate these results in patients with shoulder pain.