Effects of human recombinant parathyroid hormone treatment on the osteoporotic spine: An animal model of spinal instrumentation and fusion
This study is investigating whether parathyroid hormone 1-34 treatment before spine instrumentation and fusion surgical procedures will increase the pedicle screw fixation strength and spine fusion quality in the osteoporotic spine.
The osteoporotic animal model will be used to evaluate:
- Pedicle screw fixation using screw pullout strength
- Vertebral material mechanical properties using nanoindentation
- Fusion quantity and quality with micro-CT
Stress profiles of the lumbar intervertebral disk during flexion and extension
The primary objective of this study is to determine the effect of distraction alone and distraction combined with flexion or extension on the distribution of intradiscal pressure and stress in normal and degenerative cadaveric lumbar disks.
This will be accomplished using the technique of stress profilometry to map changes in stress distribution within the intervertebral disk during simulated flexion-distraction treatment of cadaveric motion segments from L2-L3 to L5-S1.
The patterns of stress distribution observed from this study, whether supportive of current theory or not, will be used to generate new hypotheses and design more-effective nonsurgical treatment strategies for disk-related spinal conditions. Eighteen specimens have been tested and graded with data analysis ongoing.
Vertebral fracture prediction finite element model of the human osteoporotic spine using novel computational and experimental validation approaches
- Investigators: Ahmad Nassr, M.D.; Hugo Giambini; Kai-Nan An, Ph.D.; and Andrew R. Thoreson
This project aims to improve the accuracy of vertebral wedge fracture risk prediction by developing a patient-specific model using quantitative computerized tomography and finite element methods.
The investigators plan to design a finite element method model of a vertebra capable of predicting fracture risk more precisely and validate the model using a novel experimental approach for inducing wedge fractures. This novel technique will include the vertebral body and posterior bony structure of the vertebra, intervertebral disks and adjacent vertebrae.
The researchers hypothesize that by using finite element methods and quantitative computerized tomography, they will be able to better predict wedge fracture risk based on user-defined failure criteria, specifically predicting site propagation under bending load conditions. They intend to develop a model and a process for future model development that will better predict vertebral fracture crack propagation and be fast enough for clinical applications of bone strength modeling.
Success will better predict wedge vertebral fracture in osteoporotic patients, reducing morbidity and mortality.