Dose optimization for spinal treatment effectiveness (The DOSE Study): a randomized controlled trial investigating the effects of high and low mobilization forces in patients with neck pain

Study Design: Randomized controlled trial. Objective: To determine if force magnitude during posterior-to-anterior (PA) mobilization affects immediate and short-term outcomes in patients with chronic non-specific neck pain. Background: The optimal dose of mobilization to effectively treat patients with neck pain is not known. Methods: Patients with neck pain of at least 3 months duration (n=64) were randomized to receive a single treatment of PA mobilization applied with 30N or 90N mean peak force (3 sets of 30 seconds) or a placebo (detuned laser) on the spinous process at their painful spinal level. Pressure pain threshold (PPT), pain (visual analogue scale 0-100 mm), cervical range of motion (ROM), and spinal stiffness at the painful spinal level (instrumented measurement, normalized as a percentage of C7 stiffness) were measured before, immediately after, and a mean 4.0 days (SD 1.8) following treatment (follow-up). Repeated measures analysis of covariance and Bonferroni-adjusted post-hoc tests determined group differences for each outcome measure after treatment and at follow-up. Results: At follow-up, the 90N group had less pain than the 30N group (mean difference 11.3 mm, 95% CI: 0.1, 22.6, P=.048) and lower stiffness than the placebo group (17.5%, 95% CI: 4.2, 30.9, P=.006). These differences were not present immediately after treatment. There were no significant between-group differences in PPT or ROM after treatment or at follow-up. Conclusion: A specific dose of mobilization, in terms of applied force, appears necessary for reducing stiffness, and potentially pain, in patients with chronic neck pain. Changes were not observed immediately after mobilization, suggesting its effects are not directly mechanical. Level of Evidence Therapy, level 1b