Background: In clinical diagnosis, the maximum motion of a cervical joint is thought to be found at the joint’s end-range and it is this perception that forms the basis for the interpretation of flexion/extension imaging studies.
There have however, been representative cases of joints producing their maximum motion before end-range, but this phenomenon is yet to be quantified.
Purpose: To provide a quantitative assessment of the difference between maximum joint motion and joint end-range in healthy subjects. Secondarily to classify joints into type based on their motion and to assess the proportions of these joint types.
Study design: This is an observational study.
Subject sample: Thirty-three healthy subjects participated in the study.
Outcome measures: Maximum motion, end-range motion and surplus motion (the difference between maximum motion and end-range) in degrees were extracted from each cervical joint.
Methods: Thirty-three subjects performed one flexion and one extension motion excursion under video fluoroscopy. The motion excursions were divided into 10% epochs, from which maximum motion, end-range and surplus motion were extracted. Surplus motion was then assessed in quartiles and joints were classified into type according to end-range.
Results: For flexion 48.9% and for extension 47.2% of joints produced maximum motion before joint end-range (type S). For flexion 45.9% and for extension 46.8% of joints produced maximum motion at joint end-range (type C). For flexion 5.2% of joints and for extension 6.1% of joints concluded their motion anti-directionally (type A).
Significant differences were found for C2/C3 (P = 0.000), C3/C4 (P = 0.001) and C4/C5 (P = 0.005) in flexion and C1/C2 (P = 0.004), C3/C4 (P = 0.013) and C6/C7 (P = 0.013) in extension when comparing the joint end- range of type C and type S.
The average pro-directional (motion in the direction of neck motion) surplus motion was 2.41° ± 2.12° with a range of (0.07° -14.23°) for flexion and 2.02° ± 1.70° with a range of (0.04°-6.97°) for extension.
Conclusion: This is the first study to categorise joints by type of motion. It cannot be assumed that end-range is a demonstration of a joint’s maximum motion, as type S constituted approximately half of the joints analysed in this study.
Author keywords: Maximum motion - Range of motion - Fluoroscopy - Cervical vertebrae - Neck
Author affiliations: VA, LRO, MP, RL: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark; XW: The Second Hospital of Jilin University, Jilin University, Changchun, China; MdZ: Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, 9220, Aalborg, Denmark
Corresponding author: VA—veba@hst.aau.dk
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