Pathology of the Posterior Elements

OBJECTIVE Spinal stability is attributed in part to osteoligamentous structures, including the vertebral body, facets, intervertebral discs, and posterior elements. The materials in this study provide an opportunity to augment the degenerated nucleus without removing native disc material, a procedure introduced here as “fortification.” The objective of this study was to determine the effect of nucleus fortification on lumbar disc biomechanics. METHODS The authors performed in vitro analysis of human cadaveric functional spinal units (FSUs), along with characterization and quantification of movement of the units using biomechanical data in intact, disc-only, and fortified specimens. The units underwent removal of all posterior elements and annulus and were fortified by injecting a biogel into the nucleus pulposus. Each specimen was subjected to load testing, range of motion (ROM) quantification, and disc bulge measurements. Optoelectric tracking was used to quantify disc bulge. These criteria were assessed in the intact, disc-only, and fortified treatments. RESULTS Disc-only FSUs resulted in increased ROM when compared with intact and fortified conditions. Fortification of the FSU resulted in partial restoration of normal ROM in the treatment groups. Analysis of hysteresis loops showed more linear response in the fortified groups when compared with the intact and disc-only groups. CONCLUSIONS Disc nucleus fortification increases linearity and decreases ROM.

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Mechanical Properties of Human Lumbar Spine Motion Segments—Part I: Responses in Flexion, Extension, Lateral Bending, and Torsion

Journal of Biomechanical Engineering ◽

10.1115/1.3426223 ◽

1979 ◽

Vol 101 (1) ◽

pp. 46-52 ◽

Cited By ~ 193

Author(s):

A. B. Schultz ◽

D. N. Warwick ◽

M. H. Berkson ◽

A. L. Nachemson

Keyword(s):

Mechanical Properties ◽

Lumbar Spine ◽

Mechanical Behavior ◽

Human Cadaver ◽

Lateral Bending ◽

Human Lumbar Spine ◽

Flexion Extension ◽

Spine Motion ◽

Pressure Changes ◽

Posterior Elements

In this first part of a three-part report, the mechanical behavior of 42 fresh human cadaver lumbar motion segments in flexion, extension, lateral bending, and torsion is examined. Motions and intradiskal pressure changes that occurred in response to these loads, with posterior elements both intact and excised, are reported.

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The Cervical Spine in Saethre-Chotzen Syndrome

The Cleft Palate-Craniofacial Journal ◽

10.1597/1545-1569_1997_034_0079_tcsisc_2.3.co_2 ◽

1997 ◽

Vol 34 (1) ◽

pp. 79-82 ◽

Cited By ~ 2

Author(s):

Peter J. Anderson ◽

Christine M. Hall ◽

Robert D. Evans ◽

Richard D. Hayward ◽

William J. Harkness ◽

...

Keyword(s):

Cervical Spine ◽

General Population ◽

Indirect Evidence ◽

Vertebral Fusion ◽

Spine Radiographs ◽

Posterior Elements

Twenty patients with a diagnosis of Saethre-Chotzen syndrome had their cervical spine radiographs reviewed. Radiologic abnormalities including vertebral fusion were present in 9 of the 20 patients. Fusion of both the vertebra! bodies and the posterior elements was noted, although the latter site was more common. C2–3 was the level most commonly involved, although other levels were recorded. Analysis of sequential radiographs in nine patients revealed evidence of progression In seven patients. In those studies in children aged under 2 years, only 1 of 18 films showed evidence of fusion, while in those over 2 years of age, 10 of 12 showed evidence of fusion. These results reveal that the incidence of cervical anomalies in Saethre-Chotzen syndrome is greater than that in the general population. There is both direct and indirect evidence that the vertebral fusions are progressive during childhood.

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