Biomedical Engineering and Bioengineering Commons^™

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 …

The Effect Of Plate Rotation On The Stiffness Of Femoral Liss: A Mechanical Study, Afshin Khalafi, Shane Curtiss, Scott Hazelwood, Philip Wolinsky

Biomedical Engineering

Objective: Malposition of the femoral Less Invasive Stabilization System (LISS) plate may alter its biomechanical behavior. This study compares the mechanical stability of ‘‘correctly’’ affixed LISS plates matching the slope of the lateral femoral condyle to ‘‘incorrectly’’ placed LISS plates fixed in external rotation relative to the distal femur.

Methods: A fracture gap model was created to simulate a comminuted supracondylar femur fracture (AO/OTA33-A3). Fixation was achieved using two different plate positions: the LISS plate was either placed ‘‘correctly’’ by internally rotating the plate to match the slope of the lateral femoral condyle, or ‘‘incorrectly’’ by externally rotating the plate …

Cosmm: An Undergraduate Laboratory For Engineering And Manufacturing Complex, Organic Shapes Using Nature As A Template, Daniel Walsh, Lanny Griffin, Robert Crockett

Biomedical Engineering

No abstract provided.

Effect Of Low Molecular Weight Heparin On Fracture Healing In A Stabilized Rat Femur Fracture Model, David J. Hak, Rena L. Stewart, Scott J. Hazelwood

Biomedical Engineering

The purpose of this studywas to evaluate the effect of low molecular weight heparin (LMWH) on fracture healing in a standard stabilized rat femur fracture model. A closed, mid-diaphyseal transverse fracture was created in the right femur of Long-Evans rats after insertion of a 0.8-mm K-wire into the medullarycanal. Animals were randomized to receive either LMWH (70 units/kg dalteparin) oraninjection of normal saline daily for 2 weeks. Animals were sacrificed at 2, 3, and 6 weeks. Fracture healing was assessedbyradiographs, histology, and mechanical testing. There were no significant differences between the control and LMWH groups in the percentage of animalswith …

Neural-Electronic Inhibition Simulated With A Neuron Model Implemented In Spice, Robert B. Szlavik, Abuhanif K. Bhuiyan, Anthony Carver, Frank Jenkins

Biomedical Engineering

There have been numerous studies presented in the literature related to the simulation of the interaction between biological neurons and electronic devices. A complicating factor associated with these simulations is the algebraic complexity involved in implementation. This complication has impeded simulation of more involved neural-electronic circuitry and consequently has limited potential advancements in the integration of biological neurons with synthetic electronics. In this paper, we describe a modification to a previously proposed SPICE based Hodgkin-Huxley neuron model that demonstrates more physiologically relevant electrical behavior. We utilize this SPICE based neuron model in conjunction with an external circuit that allows for …

Osteonal Effects On Elastic Modulus And Fatigue Life In Equine Bone, V. A. Gibson, S. M. Stover, J. C. Gibeling, S. J. Hazelwood, R. B. Martin

Biomedical Engineering

We hypothesized that recently formed, incompletely mineralized, and thus, relatively deformable osteons in the equine third metacarpus enhance in vitro load-controlled fatigue life in two ways. Macroscopically, there is a compliance effect, because reduced tissue elastic modulus diminishes the stress required to reach a given strain. Microscopically, there is a cement line effect, in which new osteons and their cement lines more effectively serve as barriers to crack propagation. We studied 18 4×10×100 mm beams from the medial, lateral, and dorsal cortices of metacarpal bones from 6 thoroughbred racehorses. Following load-controlled fatigue testing to fracture in 4 point bending, a …

Predictions On Preserving Bone Mass In Knee Arthroplasty With Bisphosphonates, Jeffry S. Nyman, Juan J. Rodrigo, Scott J. Hazelwood, Oscar C. Yeh, R. Bruce Martin

Biomedical Engineering

Using a computational model of bone adaptation, we investigated the long-term ability of bisphosphonates to minimize proximal bone loss that is associated with stress shielding in the tibia after long-stemmed total knee arthroplasty (TKA). When invoking bisphosphonate effects, the remodeling activity was suppressed, and the resorption size was reduced. Compared with the untreated simulation, bisphosphonate slowed the rate of bone loss after TKA (42% reduction in bone loss at 1 year). Activating the drug 3 months before the surgery reversed bone loss associated with the reduction in such activities as walking, but it did not provide any substantial benefit in …

Recombinant Human Bmp-7 Effectively Prevents Non-Union In Both Young And Old Rats, David J. Hak, Takeshi Makino, Takahiro Niikura, Scott J. Hazelwood, Shane Curtiss, A. Hari Reddi

Biomedical Engineering

The purpose of this study was to evaluate the influence of age on the effectiveness of rhBMP-7 treatment in a fracture with severe periosteal damage that is known to result in non-union formation. Closed stabilized femur fractures were produced in 3-month-old and 18-month-old rats. The fracture site was exposed and 2 mm of the periosteum cauterized circumferentially to impair normal fracture healing. The cauterized fracture site was immediately treated with either 100 mg rhBMP-7 (BMP-7 group), or with 25 xL of vehicle alone (control group). Fracture healing was evaluated with radiographs taken at 3 and 6 weeks. Animals were sacrificed …

Osteon Interfacial Strength And Histomorphometry Of Equine Cortical Bone, Robert F. Bigley, Lanny V. Griffin, Lisa Christensen, Ryan Vandenbosch

Biomedical Engineering

The interfacial strength of secondary osteons from the diaphysis of the Thoroughbred equine third metacarpal was evaluated using the fiber pushout test. The pushout was performed on 300–500 mm sections of 4x4x15mm bone blocks machined from four anatomic regions of the cortex. Pushout strength was evaluated from proximal to distal location within the diaphysis on four osteon types classified under polarized light on adjacent histologic sections from each block. The shear strength of the interfaces were estimated from shear lag theory. Differences were found in the interfacial strength of osteons based on appearance under polarized light with bright field having …