Biomedical Engineering and Bioengineering Commons^™

A Biomechanical Comparison Of Locked Plate Fixation With Percutaneous Insertion Capability Versus The Angled Blade Plate In A Subtrochanteric Fracture Gap Model, Brett D. Crist, Afshin Khalafi, Scott J. Hazelwood, Mark A. Lee

Biomedical Engineering

Objectives: The angled blade plate has been the historical standard in fixed-angle extramedullary subtrochanteric femur fracture fixation, but it requires an extensile lateral approach to the femur. Little formal evaluation exists for specifically designed percutaneous extramedullary implants. The purpose of this study was to compare 3 locked plating constructs, all with percutaneous insertion capability, with the standard 95-degree angled blade plate to determine whether specifically designed fixed-angle extramedullary implants for subtrochanteric femur fractures were biomechanically comparable to the angled blade plate.

Methods: Forty composite adult femurs were divided into 4 equal groups. The constructs evaluated included a 95-degree angled blade …

A Modification To The Group Delay And Simulated Annealing Technique For Characterization Of Peripheral Nerve Fiber Size Distributions For Non-Deterministic Sampled Data, Robert B. Szlavik

Biomedical Engineering

The ability to determine the characteristics of peripheral nerve fiber size distributions would provide additional information to clinicians for the diagnosis of specific pathologies of the peripheral nervous system. Investigation of these conditions, using electro-diagnostic techniques, is advantageous in the sense that such techniques tend to be minimally invasive yet provide valuable diagnostic information. One of the principal electro-diagnostic tools available to the clinician is the nerve conduction velocity test. While the peripheral nerve conduction velocity test can provide useful information to the clinician regarding the viability of the nerve under study, it is a single parameter test that yields …

A Simple, Yet Effective, Demonstration Of Polymeric Mechanical Behavior, Lanny Griffin, Jeffrey Swab

Biomedical Engineering

Developing an appreciation for the mechanical behavior of polymers materials in a lecture mode can be challenging for students if they have not bad the benefit of a laboratory experience . We have developed a simp le demonstration of thermoplastic polymeric behav ior using low-density polyethylene bags. The demonstration illustrates strengthening, rate effects, and directionality of strengthening and stiffness. Following the demonstration, students are better ab le to articulate the influence of structure, properties, processing , and performance as it applies to thermoplastic polymers.

Theoretical Analysis Of Alendronate And Risedronate Effects On Canine Vertebral Remodeling And Microdamage, Xiang Wang, Antonia M. Erickson, Matthew R. Allen, David B. Burr, R. Bruce Martin, Scott J. Hazelwood

Biomedical Engineering

Bisphosphonates suppress bone remodeling activity, increase bone volume, and significantly reduce fracture risk in individuals with osteoporosis and other metabolic bone diseases. The objectives of the current study were to develop a mathematical model that simulates control and 1 year experimental results following bisphosphonate treatment (alendronate or risedronate) in the canine fourth lumbar vertebral body, validate the model by comparing simulation predictions to 3 year experimental results, and then use the model to predict potential long term effects of bisphosphonates on remodeling and microdamage accumulation. To investigate the effects of bisphosphonates on bone volume and microdamage, a mechanistic biological model …

A Numerical Approach For Predicting The Impact Of Vascular Architecture On Blood Flow During Ischemic Repair, Stephanie Ann Wood, Shilpi Ghosh, Kevin Jones, Gabriel Gruionu, Trevor R. Cardinals

Biomedical Engineering

Abstract of conference presentation.

Functional Vasodilation Following Murine Chronic Hindlimb Ischemia, Matthew David Yocum, Trevor R. Cardinal

Biomedical Engineering

Abstract of conference presentation.

Fatigue Strength Of Common Tibial Intramedullary Nail Distal Locking Screws, Lanny V. Griffin, Robert M. Harris, Joseph J. Zubak

Biomedical Engineering

Premature failure of either the nail and/or locking screws with unstable fracture patterns may lead to angulation, shortening, malunion, and IM nail migration. Up to thirty percent of all unreamed nail locking screws can break after initial weight bearing is allowed at 8–10 weeks if union has not occurred. The primary problem this presents is hardware removal during revision surgery. The purposes of our study was to evaluate the relative fatigue resistance of distal locking screws and bolts from representative manufacturers of tibial IM nail systems, and develop a relative risk assessment of screws and materials used. Evaluations included quantitative …

Abnormal Collateral Artery Vasoactivity Following Chronic Ischemia, Trevor Cardinal, Thomas J. Kesler, Matthew D. Yocum

Biomedical Engineering

No abstract provided.

A Numerical Approach To Determine The Impact Of Network Remodeling On Blood Flow, Trevor Cardinal, Shilpi Ghosh, Stephanie A. Wood, Gabriel Gruionu

Biomedical Engineering

No abstract provided.

Alterations In Femoral Strain Following Hip Resurfacing And Total Hip Replacement, C. R. Deuel, A. A. Jamali, S. M. Stover, S J. Hazelwood

Biomedical Engineering

Bone surface strains were measured in cadaver femora during loading prior to and after resurfacing of the hip and total hip replacement using an uncemented, tapered femoral component. In vitro loading simulated the single-leg stance phase during walking. Strains were measured on the medial and the lateral sides of the proximal aspect and the middiaphysis of the femur. Bone surface strains following femoral resurfacing were similar to those in the native femur, except for proximal shear strains, which were significantly less than those in the native femur. Proximomedial strains following total hip replacement were significantly less than those in the …

A Novel Method For Characterization Of Peripheral Nerve Fiber Size Distributions By Group Delay, Robert B. Szlavik

Biomedical Engineering

The ability to determine the characteristics of peripheral nerve fiber size distributions would provide additional information to clinicians for the diagnosis of specific pathologies of the peripheral nervous system. Investigation of these conditions, using electrodiagnostic techniques, is advantageous in the sense that such techniques tend to be minimally invasive yet provide valuable diagnostic information. One of the principal electrodiagnostic tools available to the clinician is the nerve conduction velocity test. While the peripheral nerve conduction velocity test can provide useful information to the clinician regarding the viability of the nerve under study, it is a single-parameter test that yields no …

Teaching Physiology To Biomedical Engineers Using Team-Based Learning And Inquiry Research, Trevor R. Cardinal

Biomedical Engineering

Presentation given at conference.

Volume Effects On Yield Strength Of Equine Cortical Bone, R. F. Bigley, J. C. Gibeling, S. M. Stover, S. J. Hazelwood, D. P. Fyhrie, R. B. Martin

Biomedical Engineering

Volume effects are a fundamental determinant of structural failure. A material exhibits a volume effect if its failure properties are dependent on the specimen volume. Many brittle ceramics exhibit volume effects due to loading a structure in the presence of “critical” flaws. The number of flaws, their locations, and the effect of stress field within the stressed volume play a role in determining the structure’s failure properties. Since real materials are imperfect, structures composed of large volumes of material have higher probabilities of containing a flaw than do small volumes. Consequently, large material volumes tend to fail at lower stresses …

Fatigue Testing Of Three Peristernal Median Sternotomy Closure Techniques, Cameron Wangsgard, David J. Cohen, Lanny V. Griffin

Biomedical Engineering

Failure of a sternotomy closure because of closure system fatigue is a complication that may result in dehiscence and put the individual at risk for serious complications. The purpose of this study was to assess the fatigue performance of three peristernal median sternotomy closure techniques (figure-of-eight stainless-steel wires, figure-of-eight stainless-steel cables, or Pectofix Dynamic Sternal Fixation [DSF] stainless-steel plates) in order to quantify the potential risk of fatigue failure of these devices when subject to cyclic loads in physiologically relevant loading directions.

A Novel Method For Characterization Of Peripheral Nerve Fiber Size Distributions By Group Delay Measurements And Simulated Annealing Optimization, Robert B. Szlavik, Galen E. Turner, Iii

Biomedical Engineering

The ability to determine the characteristics of peripheral nerve fiber size distributions would provide additional information to clinicians for the diagnosis of specific pathologies of the peripheral nervous system. Investigation of these conditions, using electro-diagnostic techniques, is advantageous in the sense that such techniques tend to be minimally invasive yet provide valuable diagnostic information. One of the principal electro-diagnostic tools available to the clinician is the nerve conduction velocity test. While the peripheral nerve conduction velocity test can provide useful information to the clinician regarding the viability of the nerve under study, it is a single parameter test that yields …

Nicotinic Acetylcholine Receptor Kinetics Of The Neuromuscular Junction Simulated Using Spice: An Illustration Of Physiological Process Simulation With Conventional Circuit Simulation Software, Robert B. Szlavik

Biomedical Engineering

With the advent of modern day computational power, there is a great deal of interest in the simulation and modeling of complex biological systems. A significant effort is being made to develop generalized software packages for the simulation of cellular processes, metabolic pathways and complex biochemical reaction systems. The advantages to being able to implement and simulate complex biological systems in a virtual environment are several. Simulations of this type, if sufficiently detailed, provide experimental physiologists with the ability to visualize the dynamics of a given biological system of interest. The validity of hypotheses related to the system under study …

Action At Distance: A Ms Degree Offered Through Distance Learning As A Vector To Student Enrichment And Industrial Interaction, Lanny Griffin, Daniel Walsh, Robert Crockett, Robert B. Szlavik

Biomedical Engineering

This paper describes the development and implementation of a flourishing MS program offered through distance learning (DL). The program serves the mission of the university – polytechnic education. It provides an intense life-long-learning opportunity for some of the 300,000 degreed engineers working in California industry who can benefit from graduate education. The DL Masters Degree Program in Engineering with a Biomedical Specialization was designed and developed with verisimilitude to the on-campus program in mind. The distance students attend the same classes as students on campus. The DL program has the same learning objectives and student outcomes as those expected for …

An Automatic Alogorithm For Detecting Stent Endothelialization From Volumetric Optical Coherence Tomography Datasets, Garret T. Bonnema, Kristen O'Halloran Cardinal, Stuart K. Williams, Jennifer K. Barton

Biomedical Engineering

Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 μm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the percentage of struts covered with an anti-thrombogenic cellular lining. We developed an image analysis program to locate covered and uncovered stent struts in OCT images of tissue-engineered blood vessels. The struts were found by exploiting the highly reflective and shadowing characteristics of the metallic stent material. Coverage was evaluated by comparing the luminal …

A Case-Study Based Course On "Device Evaluation And Fda Approval", Kristen O'Halloran Cardinal

Biomedical Engineering

Preclinical evaluation of new devices and therapies is an integral part of research and development in the medical device industry, and the regulatory process for FDA approval is a major driving force behind much that goes on in a company setting. A large number of graduating biomedical engineers enter this medical device industry or a related environment upon graduation from our institution. Although these engineers are equipped to address many of the technical challenges that will arise, there is currently limited formal training in or exposure to the regulatory process that is required to bring new devices to market. Knowledge …

Elastic Modulus Of Bone Using Ultrasonic Testing, Lanny Griffin, Victor Yu

Biomedical Engineering

No abstract provided.

Biomedical Engineering Virtual Circuit Simulation Laboratories, Robert B. Szlavik

Biomedical Engineering

Circuit simulators, such as SPICE (Simulation Program with Integrated Circuit Emphasis) are useful tools that can enhance the educational experience of students in many subject areas within a biomedical engineering curriculum. Courses on biomedical instrumentation are venues for which virtual laboratory experiments, using circuit simulators, can be readily developed. The instructor can use the circuit simulation platform to illustrate relatively complex concepts, such as differential amplification, which have wide applicability to biomedical instrumentation. More advanced courses that focus on the physiology of excitable cells or neural modeling and simulation are also venues for which circuit simulators may be applied to …

Biomedical Engineering Simulation Using Visual Basic Macros In Micrsoft Excel, Lanny Griffin, Robert Crockett

Biomedical Engineering

No abstract provided.

Biomaterials Screening Experiment Using Sessile Drop Contact Angles, Lanny Griffin

Biomedical Engineering

No abstract provided.

Simulated Effects Of Marathon Training On Bone Density, Remodeling, And Microdamage Accumulation Of The Femur, Scott J. Hazelwood, Alesha B. Castillo

Biomedical Engineering

Stress fractures are mechanically induced injuries resulting from fatigue damage to bone due to repetitive loading and are common injuries occurring in runners. In this study, we used computer simulations of marathon training programs to examine the effects of endurance running on femoral density, remodeling, and microdamage accumulation. Simulated remodeling activity increased in the femoral neck and proximal cortex and predicted microdamage increased in all regions examined after 16 weeks for each program. Daily running for three years produced more microdamage than the advanced training schedule over the same time period. Areas of high remodeling and damage corresponded to clinically …

The Use Of Hinged External Fixation To Provide Additional Stabilization For Fractures Of The Distal Humerus, Christopher R. Deuel, Philip Wolinsky, Eric Shepherd, Scott Hazelwood

Biomedical Engineering

Objective: To assess improvements in fixation stability when a hinged unilateral external fixator is used to supplement compromised internal fixation for distal humerus fractures.

Methods: Removing a 1-cm section of the distal humerus in cadaveric whole-arm specimens created a comminuted distal humerus fracture model (AO type 13-A3). Fixation was then performed using different constructs representing optimal, compromised, or supplemented internal fixation. Internal fixation consisted of either 2 reconstruction plates with 1, 2, or 3 (optimal) distal attachment screws, or crossing medial and lateral cortical screws. A hinged external fixator was applied in combination with compromised internal fixation. The stability of …

Assessment Of Blood Vessel Mimics With Optical Coherence Tomography, Garret T. Bonnema, Kristen O'Halloran Cardinal, James B. Mcnally, Stuart K. Williams, Jennifer K. Barton

Biomedical Engineering

Optical coherence tomography (OCT) is an imaging mo-dality that enables assessment of tissue structural characteristics. Studies have indicated that OCT is a useful method to assess both blood vessel morphology and the response of a vessel to a deployed stent. We evaluated the ability of OCT to visualize the cellular lining of a tissue-engineered blood vessel mimic (BVM) and the response of this lining to a bare metal stent. We develop a side-firing endoscope that obtains intraluminal, longitudinal scans within the sterile bioreactor environment, enabling time-serial assessment. Seventeen BVMs are imaged with the endoscopic OCT system. The BVMs are then …

Quantitative Regional Associations Between Remodeling, Modeling, And Osteocyte Apoptosis And Density In Rabbit Tibial Midshafts, Nicole L. Hedgecock, Tamer Hadi, Andrew A. Chen, Shane B. Curtiss, R. Bruce Martin, Scott J. Hazelwood

Biomedical Engineering

Evidence suggests that osteocyte apoptosis is involved in the adaptive response of bone, although the specific role of osteocytes in the signaling mechanism is unknown. Here, we examined and correlated regional variability in indices of remodeling, modeling, osteocyte apoptosis, and osteocyte density in rabbit tibia midshafts. Histomorphometric analysis indicated that remodeling parameters (BMU activation frequency, osteon density, forming osteon density, and resorption cavity density) were lower in the cranial region compared to other quadrants. In addition, pericortical subregions displayed less remodeling relative to intracortical and endocortical ones. Modeling indices also demonstrated regional variability in that periosteal surfaces exhibited a greater …

Biomechanics Of The Rabbit Knee And Ankle: Muscle, Ligament, And Joint Contact Force Predictions, Dustin M. Grover, Andrew A. Chen, Scott J. Hazelwood

Biomedical Engineering

Mathematical models of small animals that predict in vivo forces acting on the lower extremities are critical for studies of musculoskeletal biomechanics and diseases. Rabbits are advantageous in this regard because they remodel their cortical bone similar to humans. Here, we enhance a recent mathematical model of the rabbit knee joint to include the loading behavior of individual muscles, ligaments, and joint contact at the knee and ankle during the stance phase of hopping. Geometric data from the hindlimbs of three adult New Zealand white rabbits, combined with previously reported intersegmental forces and moments, were used as inputs to the …

Volume Effects On Fatigue Life Of Equine Cortical Bone, R. F. Bigley, J. C. Gibeling, S. M. Stover, S. J. Hazelwood, D. P. Fyhrie, R. B. Martin

Biomedical Engineering

Materials, including bone, often fail due to loading in the presence of critical flaws. The relative amount, location, and interaction of these flaws within a stressed volume of material play a role in determining the failure properties of the structure. As materials are generally imperfect, larger volumes of material have higher probabilities of containing a flaw of critical size than do smaller volumes. Thus, larger volumes tend to fail at fewer cycles compared with smaller volumes when fatigue loaded to similar stress levels. A material is said to exhibit a volume effect if its failure properties are dependent on the …

Two In Vivo Surgical Approaches For Lumbar Corpectomy Using Allograft And A Metallic Implant: A Controlled Clinical And Biomechanical Study, Philbert Huang, Munish C. Gupta, Nesrin Sarigul-Klijn, Scott Hazelwood

Biomedical Engineering

Background context: Both bone graft and metallic implants have been used in combination with the necessary anterior rod or plate instrumentation to fill the voids left by vertebral body removal, with the ultimate goal of restoring stability. One type of device that has recently been introduced is an expandable titanium telescoping cage that is designed to be used as a strut implant to fill corpectomy defects. The use of these devices has met varying success. Acceptance by surgeons and spine biomechanicians has been limited by clinical failure with subsequent loss of reduction and increase in kyphosis. In order to further …