Effect of High-Velocity Low-Amplitude Manipulation on Cervical Spine Muscle Strength: A Randomized Clinical Trial

Abstract Clinical observation suggests that side-to-side differences in anterolateral neck flexor strength may be resolved by appropriate high-velocity low-amplitude manipulation of a dysfunctional upper cervical segment. We examined 67 patients with mechanical neck pain or cervicogenic headaches to evaluate the change in anterolateral neck flexor strength after upper cervical spine manipulation. We used the relative position of the atlas, determined by palpation, to predict the weaker side of anterolateral neck flexor strength. The subjects were randomly assigned to two groups. The control group received spinal manipulation to dysfunctional segments in the lower cervical spine only, and the treatment group received manipulation to dysfunctional segments in both the upper and lower cervical spine. Following manipulation of the upper and lower cervical spine, the predicted weak side of the treatment group showed a greater improvement in strength compared to the predicted strong side. Also, following manipulation, there was a greater increase in strength of the predicted weak side of the treatment group compared to the predicted weak side of the control group. We also studied the interrater reliability of positional palpation of the atlas and determined the relationship between the relative position of the atlas and anterolateral neck flexor strength.