The Relationship of the Audible Pop to Hypoalgesia Associated With High-Velocity, Low-Amplitude Thrust Manipulation: A Secondary Analysis of an Experimental Study in Pain-Free Participants

Abstract

Objective-High velocity, low amplitude (HVLA) manipulation is an effective treatment for low back pain (LBP); however, the corresponding mechanisms are undetermined. Hypoalgesia is associated with HVLA manipulation and suggests specific mechanisms of action. An audible pop (AP) is also associated with HVLA manipulation; however, the influence of the AP on the hypoalgesia associated with HVLA manipulation is not established. The purpose of the current study was to observe the influence of the AP on hypoalgesia associated with HVLA manipulation. Methods-The current study represents a secondary analysis of 40 participants. All participants underwent thermal pain sensitivity testing to their leg and low back using protocols specific to Aδ fiber mediated pain and temporal summation. Next, participants received HVLA manipulation to their low back and the examiner recorded whether or not an AP was perceived. Finally, participants underwent immediate follow up thermal pain sensitivity testing using the same protocols. Separate repeated measure ANOVAs were used to observe changes in pain sensitivity prior to and immediately following HVLA manipulation.Results-Hypoalgesia of Aδ fiber mediated pain was observed in the low back following HVLA (p< 0.05) and this was independent of whether an AP was perceived (p> 0.05). Hypoalgesia of temporal summation was observed in the lower extremity following HVLA (p< 0.05) and this was Correspondence to: Joel E Bialosky, bialosky@phhp.ufl.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Conflicts of Interest: No conflicts of interest were reported for this study. Practical Applications •An audible pop is associated with HVLA manipulation; however, the clinical and mechanistic relevance of the pop is not known.• We observed HVLA manipulation related hypoalgesia to thermal pain sensitivity and this finding was not dependent upon the presence of a pop. independent of whether an AP was perceived (p= 0.08). However, a moderate effect size for temporal summation was observed favoring participants in whom an AP was perceived. NIH Public Access Conclusion-The current study suggests hypoalgesia is associated with HVLA manipulation and occurs independently of a perceived AP. Inhibition of lower extremity temporal summation may be larger in individuals in whom an AP is perceived, but further study is necessary to confirm this finding.

Upper Cervical and Upper Thoracic Thrust Manipulation Versus Nonthrust Mobilization in Patients With Mechanical Neck Pain: A Multicenter Randomized Clinical Trial

“…Our study found significant between-group mean differences of 8.0 points (16.0%) for disability (NDI) and 2.0 points for pain; likewise, Cleland et al 21 reported between-group mean differences of 5.0 points (10.0%) for disability (NDI) and 2.0 points for pain (NPRS) at 48-hour follow-up. Perhaps the combined effect of both upper cervical and upper thoracic HVLA thrust manipulation, as compared to thoracic HVLA thrust manipulation alone, explains the greater reduction in disability (NDI) found in our study than in that found by Cleland et al 21 In addition, Puentedura et al 80 demonstrated greater reductions in disability at all follow-up points when the HVLA thrust manipulation was directed to the cervical spine rather than the thoracic spine in patients with neck pain; however, the sample size was just 24 patients and, unlike our study, the mean duration of symptoms in the Puentedura et al 80 6 and it is plausible that the clinical benefits found in our study are associated with a neurophysiological response involving temporal sensory summation at the dorsal horn of the spinal cord 3 ; however, this proposed model is currently supported only by findings from transient, experimentally induced pain in healthy subjects [3][4][5]8,34 and not in patients with neck pain. In summary, there is currently insufficient evidence to support a dominant role of any of these 3 hypoalgesic mechanisms.…”

Immediate effects of a thoracic spine thrust manipulation on the autonomic nervous system: a randomized clinical trial

“…The increased spinal neuron activity can lead to the development of hyperalgesia and allodynia 9 in the peripheral tissues and can cause increased muscle tone or the subjective sensation of pain. 14,15 Physical therapists frequently use manipulation as an intervention in the management of patients with neck pain [16][17][18][19][20] as it has been shown to be effective. [21][22][23] Although the exact physiological mechanisms underlying spinal manipulative techniques is still unknown, a few hypotheses have been proposed offering mechanical, neurophysiological, and psychological rationales.…”

“…11,24 Mechanical force used during manipulation has a direct effect on the central nervous system, creating positive neurophysiological responses resulting in a reduced overall central sensitization. 11,12,15 The effects of manipulation is beyond biomechanical changes only; 15 however, in the current literature, there is no clear explanation for some of the effects of manipulation.…”

Changes in Shoulder Pain and Disability After Thrust Manipulation in Subjects Presenting With Second and Third Rib Syndrome

“…Recently, the biomechanical effects of HVLA thrust manipulation have been under scientific scrutiny, 109 and it is plausible that the clinical benefits found in our study are associated with a neurophysiological response involving temporal sensory summation at the dorsal horn of the spinal cord 107 ; however, this proposed model is currently supported only by findings from transient, experimentally induced pain in healthy subjects 107,108,110,116,117 and not in patients with shoulder pain. In summary, there is currently insufficient evidence to support a dominant role of any of these 3 hypoalgesic mechanisms.…”