UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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Author: search.filters.author.Hill, Genevieve A-L.Subject: search.filters.subject.pediatric

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    FAILURE MECHANISMS OF PEDIATRIC GROWING ROD CONSTRUCTS
    (2017) Hill, Genevieve A-L.; Fisher, John P; Dreher, Maureen L; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Early onset scoliosis (EOS) affects a vulnerable population of young children, and occurs at critical ages when the spine and thorax are developing. Children suffering with EOS have higher mortality rates due to cardiopulmonary complications; therefore, treatment for these patients can be life-saving. Pediatric growing rod constructs are an important treatment option for young patients with severe and progressive spinal deformities because they encourage growth and correction of the spinal curvature through successive lengthening procedures. However, growing rod constructs suffer from complication rates as high as 72%, which often lead to unplanned reoperations. To help prevent future failures of the same root cause, the failure mode and mechanism must be identified, which tell us how and why the devices failed respectively. This research included the first study to examine multiple, retrieved pediatric growing rod constructs from various sites to systematically investigate these significant items. The retrieval study revealed that rod fracture (failure mode) was due to bending fatigue (failure mechanism), and stress concentrations play an important role in rod fractures. The information obtained from the retrieval study enhanced the understanding of in vivo loading conditions experienced by the device and established clinically-relevant parameters for a mechanical bench model. This research also included the development and validation of a novel mechanical bench model that successfully replicated rod fracture due to bending fatigue. A mechanical bench model that is predicated on clinical outcomes can serve as a tool for engineers and researchers who are looking to improve pediatric growing rod constructs as it will enable them to make relevant predictions about the device’s resistance to failure. For example, the model was used in this research to investigate how the unique characteristics of pediatric growing rod constructs such as construct configuration and lengthening affect mechanical performance of the device. Key recommendations regarding surgical technique were identified in the retrieval study and verified through bench testing. The data obtained during this research can ultimately be used to reduce failure rates and unplanned revisions in this patient population.