Cavitation Studies of Lumbar Zygapophysial Joints using Vibration Measurements

Abstract

The purpose of this research project was to locate the level of cavitation in zygapophysial (Z) joints in the lumbar spine (L1/L2-L5/S1) and the sacroiliac joints (SIJs) during side-posture positioning and spinal manipulative therapy (SMT). Forty healthy subjects were sought to complete this study, in which seven 1cm3 accelerometers were placed on the L1-L5 spinous processes (SPs) and the S1 and S2 sacral tubercles. Two more accelerometers were placed lateral to the midline, one 3 cm to the left and the other 3cm to the right mid-distance between the L4 and L5 accelerometers. Subjects were randomized into one of the two groups: Group 1, SMT Group (n=30) or Group 2, Side Posture Positioning Group (n=10). Data from the accelerometers was collected from both groups. Two types of reliability studies were performed: one, comparing the results of two observers (blinded to the results of one another) in identifying vertebral level of cavitations and the other, comparing presence of a cavitation found by clinician, subjects and accelerometers. Artifacts (noise signals other than cavitation) were identified, described and categorized as Flexible Spine (or loose superficial fascia), Hyper-Muscular Subjects, Resisting or Not Relaxed Subjects, Unstable Hand Contact (UHC) and Miscellaneous, depending on notes taken during data acquisition, assessment, and the unique pattern of waveform signals.

Vertebral levels of cavitations were identified and results were compared between: Group 1 vs. Group 2, targeted (L3/L4, L4/L5, and L5/S1) vs. non-targeted Z joints, left-side (up-side during side-posture positioning and SMT) vs. right-side. Fifty-six (56) cavitations were recorded from 40 subjects. A reliability study comparing the results of two observers (blinded to the results of one another) to identify cavitations from the accelerometers recordings showed “almost perfect agreement” between the two observers (Kappa = 0.841, Std E = 0.151). The reliability study comparing presence of a cavitation found accelerometers recordings of cavitations were in “almost perfect agreement” with the subjects and clinician. The clinician and subjects were also in “almost perfect agreement”. Subjects randomized into Group 1 cavitated more often (96.67% of Group 1 subjects) than those who were just held in side-posture positioning (30% of Group 2 subjects). Most cavitations were recorded on the left side (up-side 94.63%) and at the targeted Z joints (73.20%). Multiple cavitations were recorded from the same joint. Double cavitations were recorded in seven joints and, interestingly, four cavitations in one joint. A maximum of six cavitations were recorded from a subject randomized in Group 1, with four cavitations at the same joint (Left L3/L4) and two cavitations at another joint (Left L2/L3).