Laurent Balabaud, Emeric Gallard, Wafa Skalli, Bernard Dupas, Robert Roger, François Lavaste, Jean-Paul Steib


April 2003, Volume 12, Issue 5, pp 480 - 486 Original Article Read Full Article 10.1007/s00586-002-0520-9

First Online: 05 April 2003

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/cm2. 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.


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