Faculty Collaboration Database

Biomechanics of lumbar pedicle screw/plate fixation in trauma. Neurosurgery 1990 Dec;27(6):873-80; discussion 880-1

Date

12/01/1990

Pubmed ID

2274127

DOI

10.1097/00006123-199012000-00003

Scopus ID

2-s2.0-0025221347 (requires institutional sign-in at Scopus site)   40 Citations

Abstract

This investigation was conducted to determine alterations in the biomechanical strength and stiffness characteristics of the lumbar spine fixated with Steffee instrumentation. Comparative studies of these parameters were conducted using seven lumbar columns from fresh human cadavers. Three runs were conducted on each T12-L5 column: control, injured, and fixated. The specimens were loaded under the compression-flexion mode until failure (control run) and then reloaded (injury run) to the failure deformation determined in the control run. Screw/plates were then inserted one level proximal and distal to injury, and the specimens were reloaded (fixation run). Radiographs were taken before and after each trial. Data on deformation and force histories were gathered. The load-deflection response of the injured and fixated specimens were bimodal with two representative stiffnesses. Control failure loads and stiffnesses were higher than those for the injured (P less than 0.001) or fixated (P less than 0.01) spine. Initial stiffness was significantly higher for the fixated than for injured columns (P less than 0.001), but the final stiffnesses were similar. The increase in the initial stiffness in the fixated specimen compared to the injured specimen indicates the strength added to the posterior region of the spine. The relatively smaller alteration in the final stiffness between the fixated and the injured columns, corresponding to the load shared by the anterior column, may suggest that, above a critical strain level, the anterior column absorbs a higher portion of the external load and posterior fixation may be inadequate as sole treatment in trauma.

Author List

Yoganandan N, Larson SJ, Pintar F, Maiman DJ, Reinartz J, Sances A Jr

Authors

Frank A. Pintar PhD Chair, Professor in the Biomedical Engineering department at Medical College of Wisconsin
Narayan Yoganandan PhD Professor in the Neurosurgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Aged
Biomechanical Phenomena
Bone Plates
Bone Screws
Elasticity
Female
Fracture Fixation
Fractures, Bone
Humans
In Vitro Techniques
Lumbar Vertebrae
Male
Middle Aged