Quantification of Cavitation and Gapping of Lumbar Zygapophyseal Joints During Spinal Manipulative Therapy

Abstract

Objectives The purpose of this study was to use previously validated methods to quantify and relate 2 phenomena associated with chiropractic spinal manipulative therapy (SMT): 1) cavitation and 2) the simultaneous gapping (separation) of the lumbar zygapophyseal (Z) joint spaces. Methods This was a randomized, controlled, mechanistic clinical trial with blinding. Forty healthy subjects (18 to 30 years of age) without a history of low back pain participated. Seven accelerometers were affixed to the skin overlying the spinous processes of L1-L5 and the S1 and S2 sacral tubercles. Two additional accelerometers were positioned 3 cm left and right lateral to the L4/L5 inter-spinous space. Subjects were randomized into: Group 1–side-posture SMT (n=30) or Group 2–side-posture positioning (SPP, n=10). Cavitations were determined by accelerometer recordings during SMT and SPP (left-side=up-side for both groups); gapping (gapping difference) was determined by the difference between pre- and post-intervention MRI joint space measurements. Results of mean gapping differences were compared. Results Up-side SMT and SPP joints gapped more than down-side joints (0.69 vs. −0.17mm, p<0.0001). SMT up-side joints gapped more than SPP up-side joints (0.75 vs. 0.52mm, p=0.03). SMT up-side joints gapped more in males than females (1.01 vs. 0.49mm, p<0.002). Overall, joints that cavitated gapped more than those that did not (0.56vs. 0.22mm, p=0.01). No relationship was found between the occurrence of cavitation and gapping with up-side joints alone (p=0.43). Conclusions Z joints receiving chiropractic SMT gapped more than those receiving side-posture positioning alone, Z joints of males gapped more than those of females, and cavitation indicated that a joint had gapped, but not how much a joint had gapped.

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

“…Recordings (320,000 Hz sampling rate) 19–21 were then conducted during full ranges of motion (ROMs, Fig. 3).…”

“…The modification was to avoid contact with accelerometer wires and had been developed for previous studies that used accelerometers to assess cavitation during SMT. 19,21 …”

“…21,42,43 In this study, two observers, who each had over two years of experience reading accelerometer and microphone recordings in our lab, assessed each recording and reached consensus to identify crepitus and to determine the Z joint of origin for each instance of crepitus. Amplitude (measured as the change of voltage generated in the piezoelectric accelerometers) from the two primary accelerometers involved in a crepitus event (e.g., L2 and L3 accelerometers for either a left or right L2/3 crepitus) was also recorded, and the average of the two values was used as the amplitude for each crepitus.…”

“…9,10,18–21 However, there have been no studies assessing lumbar crepitus. In addition, the peer-reviewed literature has no record of a study assessing tissue characteristics of the spine using acoustics or a study comparing accelerometers with microphones in assessing acoustic data originating from the spine (including data associated with Z joint crepitus).…”

“…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.…”