Validation of a novel sham cervical manipulation procedure

Abstract

Background context: No clinical trial of spinal manipulation for chronic neck pain (NP), for either single or multiple intervention session(s), has used an effective manual sham-manipulation control group.

Purpose: Validate a practical sham cervical high-velocity low-amplitude spinal manipulation.

Study design/setting: Randomized experimental validation study in an institutional clinical research laboratory.

Patient sample: Eligible subjects were males and females, 18 to 60 years of age with mechanical NP (as defined by the International Association for the Study of Pain Classification) of at least 3 months' duration. Subjects with arm pain, any pathologic cause of NP, or any contraindication to spinal manipulation were excluded.

Outcome measures: The primary outcome was the patient's self-report or registration of group allocation after treatment. Secondary outcomes were numerical rating scale-101 for NP, range of motion (ROM; by goniometer), and tenderness (by pressure algometry).

Methods: Eligible subjects were randomly allocated to one of two groups: real cervical manipulation (RM) or sham cervical manipulation (SM). All subjects were given two procedures in sequence, either RM+SM or SM+SM. Immediately after the two procedures, subjects were asked to register any pain experienced during the procedures and to identify their treatment group allocation. Force-time profiles were recorded during all procedures. Secondary clinical outcome measures were obtained at baseline, 5 and 15 minutes after the intervention, including ROM, self-report of pain, and local spinous process tenderness. Data for each variable were summarized and tested for normality in distribution. Summary statistics were obtained for each variable and statistically tested.

Results: Sixty-seven subjects were randomized. Data from 64 subjects (32 per group) were available for analysis. There were no significant differences between the groups at baseline. One adverse event occurred in the "real" group, which was a mild posttreatment pain reaction lasting less than 24 hours. In the RM group, 50% of subjects incorrectly registered their treatment allocation; in the sham group, 53% did so. For the SM group, none of the procedures resulted in cavitation, whereas in the RM group, 87% of procedures resulted in cavitation. There were no significant changes between groups on pain, tenderness, or ROM. Force-time profiles of the RM and SM procedures demonstrated fidelity with significant differences between components as intended.

Conclusions: The novel sham procedure has been shown to be effective in masking subjects to group allocation and to be clinically inert with respect to common outcomes in the immediate posttreatment stage. Further research on serial applications and for multiple operators is warranted.

Figure 1

Head and operator arm orientations for the SM. Wide arrows show the direction of the downward force to trip the cam mechanism. The thin arrow shows the skin contact between the arm and patient’s neck.

Figure 2

RM configuration; the wide arrow shows the force to trip the cam and the thinner arrow gives one component of the intended treatment force. RM configuration; the wide arrow as in 2a; the manual contact with the operator’s thumb (thin arrow) and direction of second intended component (thinnest arrow) are shown (head is over-rotated to show thumb contact).

Figure 2

RM configuration; the wide arrow shows the force to trip the cam and the thinner arrow gives one component of the intended treatment force. RM configuration; the wide arrow as in 2a; the manual contact with the operator’s thumb (thin arrow) and direction of second intended component (thinnest arrow) are shown (head is over-rotated to show thumb contact).