Three-dimensional spine kinematics during multidirectional, target-directed trunk movement in sitting.

Area of Science:

• Biomechanics
• Human Movement Science
• Spine Kinematics

Background:

• Understanding three-dimensional spine motion during functional tasks is crucial for assessing spinal health.
• Trunk movements in a seated position, without foot support, present unique biomechanical challenges.
• Previous research has often simplified spine motion, potentially overlooking complex inter-segmental dynamics.

Purpose of the Study:

• To quantitatively assess three-dimensional spine motion during target-directed trunk movements in a seated posture.
• To compare the effectiveness of different kinematic trunk models (1, 3, and 7 segments) in capturing spine motion.
• To investigate how target distance and direction influence inter-segmental spine motion.

Main Methods:

• Subjects performed target-directed trunk leaning tasks while seated without foot support.
• A retro-reflective motion analysis system captured three-dimensional spine motion.
• Three kinematic trunk models (1, 3, and 7 segments) were applied to analyze the data.

Main Results:

• Significant differences in total trunk motion were observed across different kinematic models, target distances, and directions.
• The 7-segment model revealed complex, unevenly distributed inter-segmental spine motion.
• Motion patterns varied between spine levels and were influenced by target distance and direction, even in healthy subjects.

Conclusions:

• Inter-segmental spine motion is complex, task-dependent, and unevenly distributed.
• Multi-segmental kinematic models provide more interpretable insights into individual spine motion patterns.
• This approach can enhance the understanding of movement-related spine pathologies.