Biomaterials Commons^™

Volumetric Wear Analysis Of Polyethylene Orthopedic Liners Using Point Clouds, Gabriel Landi

Dartmouth College Master’s Theses

In vivo wear of ultra-high molecular weight polyethylene (UHMWPE) orthopedic bearings represents a major problem in shoulder and knee arthroplasty, with significant amounts of devices failing due to the complication itself, and even more due to associated reasons for retrieval, including aseptic loosening. However, quantification of UHMWPE wear has largely been limited to linear and in vitro volumetric analyses, obscuring the understanding of the amount of clinically relevant material loss. This study proposes new methods to measure articular, rim, and backside surfaces of retrieved shoulder and knee UHMWPE liners, centered around the coordinate measuring machine (CMM)-based collection of high density …

Application-Driven Materials Development Of Solid-State Conductive Composites Of Ultra-High Molecular Weight Polyethylene, Peder Solberg

Dartmouth College Ph.D Dissertations

Ultra-high molecular weight polyethylene (UHMWPE) is a linear long chain homopolymer valued for its toughness, wear resistance, and chemical inertness. In the medical field, these properties make it the material of choice for bearing surfaces despite recognized tradeoffs between wear resistance, toughness, and oxidation resistance. Electrically conductive composites of UHMWPE show promise to enable new types of smart and active load-bearing implants in a future of personalized medicine, if beneficial properties can be maintained with the addition of solid-state additives.

Clinical need-finding conducted through Dartmouth’s Training Program in Surgical Innovation revealed several potential applications for conductive, load-bearing polymers. These include: …

Soil Respiration Measurements Reveal High Retention Of Organic Carbon From Corn Residue Derived High-Lignin Fermentation Byproduct Enabling Sustainable Lignocellulosic Biofuel Production, Michelle Sun Wang

Dartmouth College Master’s Theses

While 2G biofuel production can utilize non-edible, lignocellulosic feedstocks such as agricultural residues to produce liquid fuel, harvesting crop residues is unsustainable without careful management of the soil underneath. By harvesting a fraction of the crop residues left in the field after harvest, soil health can diminish and critically, the soil organic carbon (SOC) stored in agricultural fields can decrease. Currently, in the most popular 2G process models published, the issue of soil degradation remains unresolved with residue harvest strategies receiving considerable attention in the literature and other SOC management strategies receiving far less. Specifically, the strategy of returning the …

Phase-Changing Nanodroplets As Nanotheranostic Platform For Combination Cancer Therapy, Catalina-Paula Spatarelu

Dartmouth College Ph.D Dissertations

Cancer is a cluster of diseases, and 1.8 million Americans are newly diagnosed each year. Treatment issues such as drug instability, the occurrence of severe side effects, as well as resistance make the need for solutions to improve conventional methods, like chemotherapy, apparent. Nano-sized drug-delivery platforms, particles loaded with therapeutic molecules that escape the immune system clearance and accumulate at the tumor site, were proposed as one of these solutions. Despite the expansion of the field, several aspects still need to be addressed: inconsistent delivery of the drugs, inability of measuring the effective dose being delivered to the tumor, lack …

Multimodal Ultrasound Imaging For Improved Metastatic Lymph Node Detection, Sidhartha Jandhyala

Dartmouth College Ph.D Dissertations

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and is complex in nature due to the variety of organs located in the head and neck region. Knowing the metastatic state of the lymph nodes is paramount in accurately staging and treating HNSCC patients. Currently, metastatic lymph node detection involves the use of magnetic resonance imaging and/or x-ray computed tomography, followed by biopsies for histological confirmation. The main diagnostic criteria is the size of the nodes; however, current imaging methods are not 100% accurate due natural lymph node variability. Ultrasound imaging is able to provide …

A Physical And Computational Reverse-Engineering Approach To Determine Dimensional Change And Its Relationship To Oxidation In Retrieved Orthopedic Implants, Josephine Kalshoven

ENGS 88 Honors Thesis (AB Students)

Oxidation of the Ultra-High Molecular Weight Polyethylene (UHMWPE) tibial inserts of total knee arthroplasty devices is a major factor underlying multiple modes of failure for these devices, including delamination, wear, and fracture. Previous research has demonstrated that oxidation of UHMWPE is driven by a high concentration of free radicals in the polyethylene. However, even new devices created with undetectable amounts of free radicals are oxidizing in vivo. One theory is that, in the absence of residual free radicals, oxidation is facilitated by absorbed species (e.g. lipids, ROS) delivered or exacerbated by contact stress. However, no method exists to comprehensively …