Quantification of cavitation and gapping of lumbar zygapophyseal joints during spinal manipulative therapy.
OBJECTIVE
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 participants (18-30 years old) without a history of low-back pain participated. Seven accelerometers were affixed to the skin overlying the spinous processes of L1 to L5 and the S1 and S2 sacral tubercles. Two additional accelerometers were positioned 3 cm left and right lateral to the L4/L5 interspinous space. Participants 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 = upside for both groups); gapping (gapping difference) was determined by the difference between pre- and postintervention magnetic resonance imaging scan joint space measurements. Results of mean gapping differences were compared.


RESULTS
Upside SMT and SPP joints gapped more than downside joints (0.69 vs -0.17 mm, P < .0001). Spinal manipulative therapy upside joints gapped more than SPP upside joints (0.75 vs 0.52 mm, P = .03). Spinal manipulative therapy upside joints gapped more in men than in women (1.01 vs 0.49 mm, P < .002). Overall, joints that cavitated gapped more than those that did not (0.56 vs 0.22 mm, P = .01). No relationship was found between the occurrence of cavitation and gapping with upside joints alone (P = .43).


CONCLUSIONS
Zygapophyseal joints receiving chiropractic SMT gapped more than those receiving SPP alone; Z joints of men gapped more than those of women, and cavitation indicated that a joint had gapped but not how much a joint had gapped.
Department of Research, National University of Health Sciences, Lombard, IL 60148, USA. gcramer@nuhs.edu
Gregory D
GD
Cramer
Kim
K
Ross
P K
PK
Raju
Jerrilyn
J
Cambron
Joe A
JA
Cantu
Preetam
P
Bora
Jennifer M
JM
Dexheimer
Ray
R
McKinnis
Adam R
AR
Habeck
Scott
S
Selby
Judith D
JD
Pocius
Douglas
D
Gregerson
D000054:Acceleration; D000293:Adolescent; D000328:Adult; D016001:Confidence Intervals; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000628:therapy*; D008159:Lumbar Vertebrae; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D020393:Manipulation, Spinal / Q000379:methods*; D059408:Pain Management; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D016037:Single-Blind Method; D016896:Treatment Outcome; D055815:Young Adult; D021801:Zygapophyseal Joint / Q000473:pathology*