Investigators: Scott A. Yerby, PhD and Eugene J. Carragee, MD

Summary: Pedicle screw systems are widely used to stabilize the posterior spine in the case of acute injury, or congenital deformity or disease. However it is not uncommon for these systems to fail at the bone-implant interface. The goal of this study is to investigate the effect of vertebral bone mineral density on implant life (cycles to failure) for a given loading amplitude in an in vitro spine model. Human thoracolumbar specimens (T11-L3) will be cyclically loaded in flexion from 0 to 7.5 Nm. The screw angle relative to the vertebra will be measured every 100 cycles until the angle reaches 7 degrees. We have successfully run 3 specimens and have noticed a positive trend of bone mineral density on the cycles to failure.

Findings: We have successfully run 3 specimens and have noticed a positive trend of bone mineral density on the cycles to failure. When ready, the findings will be submitted to the journal Spine.

Funding Source: PAIRE: North American Spine Society

Years: 1998-1999