Moment-rotation relationships of the ligamentous occipito-atlanto-axial complex.
The relationships between applied pure moments at the occiput (C0) and the resulting rotations at the atlanto-occipital (C0-C1) and atlanto-axial (C1-C2) joints are quantified. In axial twist, with a moment of 0.3 Nm, a mean rotation of about 2.5 degrees and 23.3 degrees was observed at C0-C1 and C1-C2 units respectively. Both the atlas and axis contributed to produce lateral bending motion. The ratio between extension and flexion rotations at C0-C1 was 2.5:1. Lateral bending and axial rotations were strongly coupled to each other. The occipito-atlanto-axial complex exhibited a large 'neutral zone' compared to lower cervical spine segments. The likely clinical significance of these findings are discussed.
Goel
V K
VK
Department of Biomedical Engineering, University of Iowa, Iowa City 52242.
Clark
C R
CR
Gallaes
K
K
Liu
Y K
YK
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001268:Atlanto-Axial Joint / Q000502:physiology*; D001269:Atlanto-Occipital Joint / Q000502:physiology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008023:Ligaments, Articular / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D012399:Rotation