Validation of a sham manipulative procedure for the cervical spine for use in clinical trials

To develop a sham manipulation procedure for the cervical spine for use in randomized clinical trials of cervical disorders.

A single-group, single-intervention study design was used. Adult neck pain subjects underwent a screening examination that included palpation for a site of cervical spine joint dysfunction. Eligible subjects underwent measurements of regional cervical ranges of motion as well as pressure algometry (tenderness) at the site of cervical joint dysfunction. Subjects were instructed that they would receive one of several types of manipulative procedures. A newly developed sham manipulation was delivered once. Subjects were then remeasured for ranges of motion and tenderness. They were asked if they had experienced any pain during the procedure, if they had experienced a "cavitation" sound, and if they thought that the procedure they received was a "real" manipulation. Finally, they were debriefed as to the deception involved in this study. A prior level of 65% was set for endorsement that the procedure was a real manipulation. Changes in pre-post measures of ranges of motion and tenderness were analyzed descriptively for clinically important differences.

Twenty eligible subjects were included (12 males, 8 females) with an average age of 30.4 (2.8) years. Twelve of the subjects were not students, with 3 of these having no prior experience with chiropractic treatment; 8 were students. Of the total sample (N = 19), 8 (42.1%) indicated that the procedure was a "real adjustment"; of the 12 nonstudents, 8 (58.3%) indicated similarly. None of the procedures in the final sample resulted in a cavitation, and none of the subjects registered the procedure as painful. None of the measures for ranges of motion or tenderness showed clinically important changes.

The sham cervical manipulation studied here appears to approximate the necessary features of a placebo maneuver in that it is perceived by a majority of nonstudent neck pain subjects to be a real manipulation, although it does not produce any important change in cervical status. The small sample size of nonstudent participants precludes a strong recommendation for this procedure at this time.