Analysis of zygapophyseal joint cracking during chiropractic manipulation.

OBJECTIVES

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.

DESIGN

Randomized experimental study.

SETTING

Macquarie University, Centre for Chiropractic, Summer Hill, New South Wales.

SUBJECTS

Fifty asymptomatic subjects were recruited from the students and staff of the above college.

INTERVENTION

Single, unilateral "diversified," high velocity, low amplitude, rotatory thrust technique.

MAIN OUTCOME MEASURES

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.