Development and Analysis of a High Speed Bone Fracture Fixation Technology

This dissertation investigates bone fracture fixation. In the proposed method, bone fractures are stabilized using multiple bioresorbable metallic or polymer dartsails that are inserted into bone at high velocity and which are subsequently incorporated/absorbed by the body so that removal is unnecessary. This dissertation will introduce the proposed method in detail and discuss its advantages to standard bone fracture fixation techniques. Prior work relevant to fracture healing and potential dart materials will be discussed. The dissertation highlights many of the issues that may be encountered during final product design. Prototype work also provided an extensive framework for the development and initial validation of analytical and numerical models.

A major focus of this dissertation is to describe the numerical models that were used to analyze dart penetration in bone. The models gave insight into the importance of various design and material parameters on penetration performance. The results are useful for device design since many of the parameters cannot be varied easily in an experimental setup. The numerical models also show the bone and dart material reaction to impact stresses and high strain rates.

Another focus of this dissertation is the mechanical characterization of pinnedailed constructs in bone and bone analogs. One set of experiments will use foam analog femurs to compare the performance of nails and traditional bone screws in fixating femoral condylar fractures. Nails are a viable alternative to bone screws for demanding applications. Nail and screw pullout forces in foam bone analogs and freshly slaughtered porcine bone were characterized since pullout is expected to be a common failure mode.

The models and experiments presented in this dissertation should provide a basic knowledge of various mechanical issues that arise in the development and use of this novel technology.