Distribution of Cavitations as Identified with Accelerometry During Lumbar Spinal Manipulation

Abstract

Objective This project determined the location and distribution of cavitations (audible sounds producing vibrations) in the lumbar zygapophyseal (Z) joints that were targeted by spinal manipulative therapy (SMT). Methods This randomized, controlled, clinical study assessed 40 healthy subjects (20 male, 20 female), 18–30 years of age, that were block randomized into SMT (Group 1, n=30) or side-posture positioning only (Group 2, control, n=10) groups. Nine accelerometers were placed on each patient (7 on SPs/sacral tubercles of L1–S2 and 2 placed 3 cm left and right lateral to the L4/L5 interspinous space). Accelerometer recordings were made during side-posture positioning (Groups 1 and 2) and SMT (Group 1 only). The SMT was delivered by a chiropractic physician with 19 years of practice experience and included 2 high-velocity, low-amplitude thrusts delivered in rapid succession. Comparisons using chi-square or McNemar’s test were made between number of joints cavitating from: Group 1 vs. Group 2, up-side (contact side for SMT) vs. down-side, and Z joints within the target area (L3/L4, L4L5, L5/S1) vs. outside the target area (L1/L2, L2/L3, sacroiliac). Results Fifty-six cavitations were recorded from 46 joints of 40 subjects. Eight joints cavitated more than once. Group 1 joints cavitated more than Group 2 joints (p<0.0001), up-side joints cavitated more than down-side joints (p<0.0001), and joints inside the target area cavitated more than those outside the target area (p<0.01). Conclusions Most cavitations (93.5%) occurred on the up-side of SMT subjects in segments within the target area (71.7%). As expected, SMT subjects cavitated more frequently than side-posture positioning only subjects (96.7% vs. 30%). Multiple cavitations from the same Z joints had not been previously reported.

Paraspinal Muscle Spindle Response to Intervertebral Fixation and Segmental Thrust Level During Spinal Manipulation in an Animal Model

“…This concept of a mechanoreceptor activation gradient is supported by biomechanical studies showing that while a majority of HVLA-SM related cavitations are typically confined to a 3 contiguous vertebra area, more distant cavitations do occur albeit with less frequency. 29,31 In addition, HVLA-SM has been shown to produce measurable in vivo intervertebral motions at remote vertebra 63 and less forceful grade IV posterior-to-anterior spinal mobilizations applied at each lumbar spinous process elicit vertebral movement at all levels of the lumbar spine as demonstrated using in vivo dynamic MRI studies. 64,65 While it remains mechanistically unclear, various theories have been proposed of how HVLA-SM mechanoreceptor stimulation could produce sustained physiological changes.…”

“…31 A more recent study found that only 71.7% of HVLA-SM related cavitations are confined to a 3 vertebral segment area. 29 Despite the importance typically imputed to clinically identifying the precise level of spinal joint fixation and contacting that target level for an HVLA-SM, it is not clear to what extent fixated joints (targeted) would respond differently from non-fixated joints (non-targeted) to HVLA-SM.…”

“…Individuals undergoing spinal manipulation often present with intervertebral joint dysfunction at one or more segmental levels, 4,7,13,49–51 and manipulative thrust force may not be delivered accurately to the clinically identified site of spinal joint dysfunction. 29–34 …”

A Feasibility Study to Assess Vibration and Sound From Zygapophyseal Joints During Motion Before and After Spinal Manipulation

“…Those who passed the initial screening were scheduled for an examination where a research chiropractic physician conducted a thorough history and physical examination that included orthopedic and neurological tests to ensure subjects were selected who met stringent inclusion and had none of the exclusion criteria. Separate criteria that had been previously developed and implemented for healthy 19,20 and LBP subjects 37 were used in this study. Generally, healthy subjects had no current LBP, known spinal pathology, or spinal surgery; and no previous history of LBP lasting more than 2 weeks, or no more than 3 episodes of LBP of brief duration (one week) in any given year.…”

“…19–21 This feasibility study (n=10) was designed to continue the process of addressing the current gaps of knowledge by further developing previous methods and evaluating additional methods to assess and localize Z joint crepitus recorded during lumbar motion both before and after SMT. More specifically, this study evaluated recordings made simultaneously from accelerometers and a specialized directional microphone.…”