Open AccessBiomechanical evaluation of a bipedicular spinal fixation device: three different strength tests
Author(s) -
L. Balabaud,
Emeric Gallard,
Wafa Skalli,
Bernard Dupas,
René Robert,
F. Lavaste,
Jean-Paul Steib
Publication year - 2003
Publication title -
european spine journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.448
H-Index - 136
eISSN - 1432-0932
pISSN - 0940-6719
DOI - 10.1007/s00586-002-0520-9
Subject(s) - medicine , contouring , compression (physics) , universal testing machine , fixation (population genetics) , thoracic vertebrae , orthodontics , lumbar vertebrae , surgery , materials science , lumbar , composite material , ultimate tensile strength , population , environmental health , engineering drawing , engineering
Disadvantages of thoracic posterior implants and developments in rod contouring in situ led to the design of a new spinal implant: the bipedicular spinal fixation device (BSF). The BSF is composed of two bifid hooks linked by a compression transverse connector and inserted into the costo-vertebral and costo-transverse joints. The aim of this biomechanical study was to determine the loading tolerance of the BSF. Three strength tests-a pull-out test, a lateral load-to-failure test and a uniaxial transversal compression test to failure-were performed using six human thoracic spines on an Instron testing device. Specimen evaluation consisted of: bone mineral density (BMD) measurement with the dual-energy X-ray absorptiometry (DEXA) technique, cortical thickness measurements and a morphometric study. The mean values for load-to-failure in the posterior and lateral tests were 324 N and 400 N respectively. The mean value of the uniaxial compression was 988 N. The mean BMD estimated by DEXA was 0.557 g/cm(2). The BSF loading tolerance was compatible with the in situ rod contouring technique requirements when we considered posterior and lateral pull-out tests. The transversal compression test determined the appropriate and efficient BSF tightening force.