FROM:
J Manipulative Physiol Ther 2005 (Nov); 28 (9): 662–666
Howard Vernon, DC, PhD, FCCS, Katherine MacAdam, DC, Victoria Marshall, BSc, DC, Maryse Pion, BScPT, DC, Magdalena Sadowska, DC
Canadian Memorial Chiropractic College, Toronto, Ontario, Canada. hvernon@cmcc.ca
OBJECTIVE: To develop a sham manipulation procedure for the cervical spine for use in randomized clinical trials of cervical disorders.
METHODS: 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.
RESULTS: 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.
From the Full-Text Article:
Discussion
This study was designed to determine if a novel sham cervical manipulative procedure was “effective” to the extent that it resulted in no significant change in clinical status, but was perceived by subjects to be a real manipulation. Should these objectives be met, then this maneuver could be considered for use as a placebo chiropractic treatment in future randomized clinical trials for treatment of neck-related disorders.
Several limitations must be considered with these results. The sample size was small, limiting its ability to achieve the predicted level of agreement by subjects on whether they considered that the maneuver was a real manipulation. Furthermore, the sample was composed of two groups who had unequal experience with chiropractic treatment. It can certainly be concluded here that future studies should not employ students currently in a chiropractic program, although they may profess that they have not previously had a cervical manipulation.
Nonstudents in this sample (63%) were much more likely to have the perception that the procedure was a real adjustment. The level of agreement among these participants was just short of our target level.
Even if the target level of deception had been achieved, if the proposed maneuver actually produced some important change in physical findings such as ranges of motion and local tenderness, then it would fail to achieve overall practicability as a sham procedure. The procedure used in this study appears to produce no important change in either a positive (therapeutic) or negative (harm) direction. That is, it appears to be therapeutically inert and, thus, qualifies for that aspect of a placebo maneuver.
Participants provided helpful information on which aspects of the intervention made them feel that the procedure was a real manipulation. Most patients believed that the absence of a cracking sound was the biggest indicator that the procedure was not real. A couple of patients believed that the sham adjustment actually produced a specific correction to the vertebrae.
Several researchers have remarked on the issue of the cracking sound accompanying what is presumed to be a successful manipulation of the spine. [6-8] Some subjects (in previous studies and in the present one) have indicated that the absence of this sound convinces them that the procedure is not a real manipulation. Future research on sham cracking sounds might lead to greater success in subject believability. We undertook the present study without such contrivances to determine what level of success could be obtained solely by a procedure involving manual contacts and apparent thrusting. Our results come close to full success, so perhaps additional elements are not necessary.
CONCLUSIONS:
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.
