title: Analysis of zygapophyseal joint cracking during chiropractic manipulation.
abstract: OBJECTIVE
  To determine if there is a relationship between the side of head rotation and the side of joint crack during "diversified" rotatory manipulation of the cervical spine.
  
  
  METHODS
  Randomized experimental study.
  
  
  METHODS
  Macquarie University, Centre for Chiropractic, Summer Hill, New South Wales.
  
  
  METHODS
  Fifty asymptomatic subjects were recruited from the students and staff of the above college.
  
  
  METHODS
  Single, unilateral "diversified," high velocity, low amplitude, rotatory thrust technique.
  
  
  METHODS
  Joint crack sound wave analysis of digital audio tape (DAT) recordings, taken from two skin mounted microphones positioned on either side of the cervical spine.
  
  
  RESULTS
  All 50 subjects exhibited at least one audible joint crack sound during manipulation. Forty-seven subjects (94%) exhibited cracking on the ipsilateral side to head rotation (95% confidence interval, 83.5% to 98.7%). One subject exhibited joint cracking on the contralateral side only, while two subjects exhibited bilateral joint crack sounds. There was a statistically significant lower rate of exclusively ipsilateral joint cracking in subjects with a history of neck trauma (80% vs. 100%, p = .023).
  
  
  CONCLUSIONS
  This research suggests that during the "diversified" rotatory manipulation of the cervical spine utilized in this study, there is a higher occurrence of the joint crack on the ipsilateral side to head rotation.
authors.affiliation: Macquarie University, Centre for Chiropractic, Summer Hill, New South Wales.
authors.forename: J W
authors.initials: JW
authors.lastname: Reggars
authors.forename: H P
authors.initials: HP
authors.lastname: Pollard
mesh_terms: D000293:Adolescent; D000328:Adult; D002574:Cervical Vertebrae; D002684:Chiropractic; D005260:Female; D006801:Humans; D007596:Joints / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012399:Rotation