Biomaterial Database

The effect of facet geometry on the axial torque-rotation response of lumbar motion segments. 1990

A M Ahmed, and N A Duncan, and D L Burke

Department of Mechanical Engineering, McGill University, Montreal, PQ, Canada.

The objective of this study is to examine the effect of the facet geometry on the axial torque-rotation response of lumbar motion segments. The three-dimensional facet geometry of 35 L2-3 and 35 L4-5 specimens has been quantified in terms of seven parameters from computed tomographic transverse sections taken at 2-mm intervals. The motion segments have then been subjected to axial torque, for a variety of preload conditions, to establish the axial torque-rotation response. There exists significant variation of facet geometry between the segment levels; however, the degree of facet asymmetry is identical for each level. No significant correlation exists between the lumbar facet geometry and the axial torque-rotation response. The facet joints do, however, act as a "positive stop" to axial rotation, regardless of their orientation. Therefore, axial rotation sufficient to cause disc injury may only be possible after facet failure.

UI	MeSH Term	Description	Entries
D007403	Intervertebral Disc	Any of the 23 plates of fibrocartilage found between the bodies of adjacent VERTEBRAE.	Disk, Intervertebral,Intervertebral Disk,Disc, Intervertebral,Discs, Intervertebral,Disks, Intervertebral,Intervertebral Discs,Intervertebral Disks
D008159	Lumbar Vertebrae	VERTEBRAE in the region of the lower BACK below the THORACIC VERTEBRAE and above the SACRAL VERTEBRAE.	Vertebrae, Lumbar
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D002102	Cadaver	A dead body, usually a human body.	Corpse,Cadavers,Corpses
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012399	Rotation	Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Clinorotation,Clinorotations,Rotations
D013314	Stress, Mechanical	A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.	Mechanical Stress,Mechanical Stresses,Stresses, Mechanical