Angular Kinematic Analysis of Supine Cervical Thrusts Performed by Chiropractors and Chiropractic Students on...

The purpose of this study was to examine characteristics of cervical axial rotation and other motion components during cervical spine manipulation.

Eleven doctors of chiropractic (DCs), 10 chiropractic students with patient experience, and 16 inexperienced students from our institution each performed 4 thrusts on a mannequin. The thrust measured is an essential component of chiropractic cervical spine manipulation, also known as a chiropractic adjustment. The mannequin was designed for chiropractic education and outfitted with inertial measurement units for motion capture. Data were analyzed in Excel for rotation, lateral bending, and flexion-extension at thrust onsets and peaks. Differences between groups were analyzed in R (R Foundation) using Kruskal-Wallis tests, followed by Dunn tests for pairwise comparisons.

Mean rotation for DCs was 19.3° at thrust onset and 33.9° at peak; mean peak lateral bending and cervical extension were 32.0° and 10.4°, respectively. On average, 14.6° of rotation occurred in 144 milliseconds between onset and peak, with rotational velocity and acceleration maximum values of 192.9°/s and 4427°/s², respectively. Most student characteristics were similar, but DCs' acceleration means were significantly higher (Kruskal-Wallis P = .019), and experienced students used significantly greater lateral bending at onset (Kruskal-Wallis P = .049) and peak (P = .023).

Mean axial rotation for DCs during chiropractic cervical spinal adjustments was less than 34° at peak; most other measures were similar to previously reported findings.