• Keller MA
• Russell BS
• Hosek RS
• Owens EF Jr

• Manikins
• Manipulation, Cervical
• Range of Motion, Articular
• Students, Chiropractic

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

Methods: 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.

Results: 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).

Conclusion: 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.

Author keywords: Cervical Vertebrae; Chiropractic; Kinematics; Manikins; Manipulation; Spine. 

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