2009 Faculty Researchers

Theodore Choma, MD

Testing Pedicle Screw Failure in Cadaveric Osteoporotic Vertebrae

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Department

Orthopaedic Surgery

Office Location

Missouri Spine Center, 402 N Keene St, Ste 100

Phone #:

Office: (573) 882-1440

Summary

Currently, modern spine surgical techniques encounter great difficulty in achieving and holding fixation of osteoporotic vertebrae in cases of fracture and / or deformity. This project will outline the technical challenges facing surgeons and present a protocol under which a new type of fenestrated pedicle screw may be tested with/ without Confidence cement augmentation. This will be compared to the standard Expedium screw with / without cement augmentation as well. Tests will be performed in human cadaveric vertebrae and comparison failure loads, as well as failure modes will be assessed. Finite element analysis will accompany the bench – testing to improve understanding of fixation mechanisms and failure modes.

It is the purpose of this test proposal to provide a precise and repeatable method to compare the specific performance of pedicle based fixation systems in resisting toggle and pullout failure in osteoporotic bone samples. It is furthermore the aim or this proposal to compare the performance of pedicle screws using previously established standards of pure axial pullout loading to new methods of combined pullout and toggle loading. Cadaveric vertebral samples provide a natural and appropriate geometric and material sample for study but may lead to significant variability do to natural patient variation. Thus, they will be assessed with DEXA and CT imaging prior to use.

The Summer Research Fellow will be involved in the experimental apparatus setup, project meetings, specimen preparation, testing, and data reduction. He / she will work closely with the PI. The Research Fellow will be directly supervised by PhD and MD co-investigators. The Fellow will also have the opportunity to interact closely with physician members of the Orthopaedic Spine Service.