Investigating Neck Joint Contribution to Postural Stability

Kyungeun Jung, Eunse Park, Songhee Cheon
Purpose:

This study investigates how neck movement and joint stiffness affect postural control and Center of Mass (CoM) stabilization under various conditions, including quiet standing with active chin-tucking and passive bracing. The primary objective is determining whether neck joint stiffness contributes to flexible postural control strategies. 

Methods:

Thirteen healthy young participants (6 males, 7 females; mean age 26.0±6.6 years) volunteered for this study. Subjects stood quietly for 2-minute trials under four conditions: (1) Standing with eyes open(EO), (2) Standing with eyes closed (EC), (3) Standing with active chin-tucking (AC), and (4) Standing with passive bracing (PB). Body movements were captured using a 12-camera Qualysis motion measurement system, while two force platforms measured the center of pressure (CoP). Uncontrolled Manifold (UCM) Analysis was applied to partition joint variance into 'good' variance (VUCM), which reflects motor equivalent joint combinations consistent with CoP stability over time, and 'bad' variance (VORT), which leads to variability in CoP stability.

Results:

No significant differences in CoP movement were observed across conditions, indicating overall balance stability. However, UCM analysis suggests that joint compensation may stabilize the CoM without noticeable changes in CoP across conditions. Except for the eyes-closed condition, VUCM was significantly higher than VORT, indicating that most joint angles were coordinated to stabilize the CoM in both horizontal and vertical planes and in 2-dimensional space. While VUCM varied across conditions, VORT remained consistent throughout.

Conclusion(s):

Changes in neck joint control significantly influence postural control strategies. Active neck engagement increases flexibility, while passive restriction reduces it without compromising CoP stability. These findings underscore the critical role of the cervical spine in maintaining balance and suggest potential targeted interventions for individuals with postural control deficits.

Implications:

This study enhances our understanding of the role of the neck joint in postural control within a multisegmented model. A better understanding of the neck joint's contribution to upright posture highlights the importance of neck alignment in maintaining postural stability.

Funding acknowledgements:
This research is supported by the Department of Physical Therapy at the University of North Georgia.
Keywords:
Neck Joint
Postural stability
Uncontrolled Manifold Analysis
Primary topic:
Occupational health and ergonomics
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
University of North Georgia
Provide the ethics approval number:
2024-031-C&U
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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