Biomedical Engineering and Bioengineering Commons^™

A Novel Ultrasound Elastography Technique For Evaluating Tumor Response To Neoadjuvant Chemotherapy In Patients With Locally Advanced Breast Cancer, Niusha Kheirkhah

Electronic Thesis and Dissertation Repository

Breast cancer is the second most diagnosed cancer in women, estimated to affect 1 in 8 women during their lifetime. About 10% to 20% of new breast cancer cases are diagnosed with locally advanced breast cancer (LABC). LABC tumors are usually larger than 5 cm and/or attached to the skin or chest wall. It has been reported that when such cases are treated with surgery alone, metastasis and mortality rates are high, especially where skin involvement or attachment to the chest wall is extensive. As such, efficient treatment for this kind of breast cancer includes neoadjuvant chemotherapy (NAC) to shrink …

In Vitro Analyses Of The Contributions Of The Hip Capsule To Joint Biomechanics, Emma Donnelly

Electronic Thesis and Dissertation Repository

Optimal management of the hip capsule during arthroscopic surgery has not been established. The impact of incisions made to the capsule during minimally invasive procedures on joint biomechanics, and whether repair provides any benefit, continue to be debated. The effectiveness of capsular repair to restore native kinematics may be insufficient. Therefore, a better understanding of joint behavior during various capsule conditions is needed. A new robotic system was used to analyze the effect of progressive capsulotomy incision and repairs on the behavior of a normal hip within range of motion (ROM) limits with respect to the intact joint. Complete repairs …

An Investigation On The Influences Of Radial Head Hemiarthroplasty Stem Fixation Techniques On Articular Mechanics, Jakub Szmit

Electronic Thesis and Dissertation Repository

Radial head hemiarthroplasty design has been extensively studied with a focus on utilizing the geometrical characteristics of the native radial dish as a guide of implant placement and design. Although implant design has been studied, optimal radial head implant fixation technique remains unknown. This thesis focused on the effect of stem fit on radiocapitellar contact mechanics, using both finite element and experimental bench-top approaches. Additionally, investigation into the impact of varus/valgus malalignment of the radial head in both the native state and following hemiarthroplasty was conducted. It was found that loose fitting a smooth stem axisymmetric radial head implant through …

Acromial Insufficiency Fractures In Reverse Total Shoulder Arthroplasty: A Biomechanical Study, Alicia Kerrigan

Electronic Thesis and Dissertation Repository

Reverse total shoulder arthroplasty (RTSA) is increasingly utilized in the aging population, with a growing list of surgical indications including rotator cuff tear arthropathy, proximal humerus fractures, and revision arthroplasty. Acromial insufficiency fractures following RTSA are poorly understood, difficult to diagnose, and associated with inferior clinical outcomes. There is limited knowledge in the literature regarding the etiology of post-operative acromial fractures. The purpose of this study is to evaluate the role of implant parameters on acromial strain following RTSA.

Using a cadaveric model, a custom designed modular RTSA system was implanted that allowed for evaluation of modifiable parameters including glenoid …

The Development Of A Temporomandibular Force Simulator To Study Craniofacial Strain In-Vitro, Kenneth Kc Ip

Electronic Thesis and Dissertation Repository

An in-vitro musculoskeletal loading simulator was developed to replicate the internal forces of mastication, and then employed in a comparison of clinically relevant facial fracture repairs. Muscle forces are simulated by pneumatic pistons via 3D printed mounts that are reverse-engineered from CT scan to match muscle attachment sites, which are adhered to bone in order to simulate native stress distributions. Bite force and bone strain pattern of the craniofacial structure under load were measured using a force sensor and strain gauges respectively. In a series of five fresh-frozen cadaveric heads, it was found that strain patterns of the craniofacial structure …

Examining Reverse Total Shoulder Arthroplasty Baseplate Fixation In Patients With E2-Type Glenoid Erosion, Matthew D. Mahaffy

Electronic Thesis and Dissertation Repository

Superior glenoid erosion of the shoulder joint is a result of humeral subluxation caused by rotator cuff tears, and can be addressed using implants, specifically reverse total shoulder arthroplasty. This thesis examined the regional variations of bone present in superiorly eroded glenoids, established a baseline for regular RTSA baseplate fixation in patients with this defect, and compared the effect of geometric baseplate differences on implant fixation. The superiorly eroded glenoids demonstrated similar regional bone density variations as normal glenoids, and the superior and inferior regions of the glenoid demonstrated the densest and least dense cancellous bone, respectively. These regions also …

The Effect Of Radial And Ulnar Length Change On Distal Forearm Loading, Ahaoiza D. Isa

Electronic Thesis and Dissertation Repository

The effect of distal radial and ulnar length change on forearm bone loading is not well understood during simulated dynamic wrist loading. This thesis presents two studies which investigate the effect of these length changes on distal forearm loading under simulated dynamic wrist motion. The first study investigates the effect of radial length change on axial loading at the distal radius and ulna and relationship between ulnar variance and distal forearm loading. The complex variation in axial loads in the distal radius and during length change and dynamic wrist motion were studied and discussed. There was no correlation between native …

The Efficacy Of Bionate As An Articulating Surface For Joint Hemiarthroplasty, Sarah Dedecker

Electronic Thesis and Dissertation Repository

Hemiarthroplasty procedures replace the diseased side of the joint with an implant to maximize bone preservation while maintaining more native anatomy than a total joint replacement. Even though hemiarthroplasty procedures have been clinically successful, they cause progressive cartilage damage over time due to the use of relatively stiff metallic implant materials. This work investigates the role of low moduli implant material on implant-cartilage contact mechanics and early in vitro cartilage wear. A finite element simulation was developed to assess the effect of low moduli implants in the range of 0.015-0.288 GPa on contact mechanics. Higher contact area and lower peak …

Markerless Radiostereogammetry Of The Shoulder Joint In Humans: Comparisons Of Scapulohumeral Kinematics Between Individuals With Healthy And Supraspinatus-Impaired Shoulders, Ashley N. Hannon

Electronic Thesis and Dissertation Repository

The purpose of this collection of studies was to further develop the knowledge of shoulder motion in order to better understand joint function through direct measurement of 3D scapulohumeral joint kinematics using a technique of high accuracy. Markerless, bi-planar fluoroscopic radiostereometric analysis using a generic shoulder model was developed in this thesis, reducing the amount of radiation exposure to subjects. The studies compared kinematic data of the scapulohumeral joint in six degrees of freedom with a precise, in-vivo measuring technique. Data were collected on young and older healthy individuals, individuals with a torn supraspinatus and post-surgical intervention.

Although this generic …

Fundamentals Of The Biomechanical Characteristics Related To The Loading Of Reverse Total Shoulder Arthroplasty Implants And The Development Of A Wear Simulation Strategy, G Daniel G. Langohr

Electronic Thesis and Dissertation Repository

A greater understanding of reverse total shoulder arthroplasty (RTSA) in terms of articular contact mechanics and wear is essential for the optimization of current surgical technique and future implant design. Despite the prevalence of RTSA for shoulder reconstruction, there is little information in current literature regarding the effects of changes in implant parameters on articular contact mechanics and wear. The present work describes the use of in-vitro cadaveric studies, a computational model of the articular contact surfaces, and the development and implementation of a wear simulation strategy to assess RTSA contact mechanics and wear.

The articular loading characteristics of RTSA …

Effect Of Hemiarthroplasty Implant Contact Geometry And Material On Early Cartilage Wear, Alana Khayat

Electronic Thesis and Dissertation Repository

Hemiarthroplasty is a minimally invasive, cost-effective alternative to total arthroplasty in joints of the upper limb. Though these procedures reduce patient morbidity while restoring joint kinematics, their longevity is limited by wear of the adjacent cartilage. This work investigates the roles of contact geometry and implant stiffness on cartilage wear with the aim of elucidating the mechanics that contribute to cartilage damage. An in vitro study examined the influence of implant geometry on cartilage wear using a pin-on-plate wear simulator. A significant decrease in volumetric wear was observed as contact area increased, which suggests that maximizing contact area should be …

The Effect Of Fixation Plate Length On Spinal Instability Following Anterior Cervical Plate Fixation For The Repair Of In Vitro Flexion-Distraction Injuries, Abdulaziz J. Al-Kuwari

Electronic Thesis and Dissertation Repository

Abstract:

The Effect of Fixation Plate Length on Spinal Instability Following Anterior Cervical Plate Fixation for the Repair of in Vitro Flexion-Distraction Injuries

Introduction: Anterior cervical decompression and fusion with a plate (ACDFP) is a commonly performed treatment following a traumatic injury to the subaxial cervical spine. The purpose of the presented work was to determine the biomechanical effect of plate length on cervical spine kinematic stability following ACDFP stabilization for a simulated traumatic injury.

Methods: Eleven fresh-frozen cadaveric C5-C6 and C6-C7 motion segments were examined in this study. To assess kinematics, flexibility testing was performed on each specimen …

Development Of An In-Vitro Passive And Active Motion Simulator For The Investigation Of Shoulder Function And Kinematics, Joshua W. Giles

Electronic Thesis and Dissertation Repository

Injuries and degenerative diseases of the shoulder are common and may relate to the joint’s complex biomechanics, which rely primarily on soft tissues to achieve stability. Despite the prevalence of these disorders, there is little information about their effects on the biomechanics of the shoulder, and a lack of evidence with which to guide clinical practice. Insight into these disorders and their treatments can be gained through in-vitro biomechanical experiments where the achieved physiologic accuracy and repeatability directly influence their efficacy and impact.

This work’s rationale was that developing a simulator with greater physiologic accuracy and testing capabilities would improve …

Design And Development Of A Novel Expanding Pedicle Screw For Use In The Osteoporotic Lumbar Spine, Parham Rasoulinejad

Electronic Thesis and Dissertation Repository

Pedicle screws are commonly utilized in spinal surgery; however, traditional designs often do not provide adequate fixation in osteoporotic spines. The objective of this thesis was to develop a novel expanding screw for use in osteoporotic lumbar pedicles. Helical screws capable of expanding post insertion were built on a rapid prototype machine. A materials testing machine performed axial load to failure tests in both Sawbones and cadaveric specimens comparing the new design to traditional screws (rate = 10mm/min to 20 mm). Output parameters included yield load, ultimate load, stiffness, energy to failure and total energy. The expanding screw showed a …

An Investigation Of Subaxial Cervical Spine Trauma And Surgical Treatment Through Biomechanical Simulation And Kinematic Analysis, Stewart D. Mclachlin

Electronic Thesis and Dissertation Repository

In vitro biomechanical investigations can help to identify changes in subaxial cervical spine (C3-C7) stability following injury, and determine the efficacy of surgical treatments through controlled joint simulation experiments and kinematic analyses. However, with the large spectrum of cervical spine trauma, a large fraction of the potential injuries have not been examined biomechanically. This includes a lack of studies investigating prevalent flexion-distraction injuries. Therefore, the overall objective of this thesis was to investigate the changes in subaxial cervical spine kinematic stability with simulated flexion-distraction injuries and current surgical instrumentation approaches using both established and novel biomechanical techniques.

Three in vitro …

The Contact Mechanics And Kinematics Of Radial Head Implants, Hannah L. Shannon

Electronic Thesis and Dissertation Repository

A number of commercially available radial head (RH) implants are used for the management of RH fractures. The optimal shape of a RH implant to restore joint mechanics to the native state has not been established. This work compares radiocapitellar contact and kinematics for three implant designs as well as the native RH. These implants include an axisymmetric, a quasi-anatomic and a patient-specific design. When compared to the native RH, only the axisymmetric implant was significantly different in contact area (p=0.008). Active and passive forearm supination was assessed for differences in translations of the RH. Significant differences were found in …

Development Of An Active Elbow Motion Simulator And Coordinate Systems To Evaluate Kinematics In Multiple Positions, Louis M. Ferreira

Electronic Thesis and Dissertation Repository

Elbow disorders are common as a consequence of both traumatic and degenerative conditions. Relative to disorders of the lower limb, there is comparatively little evidence to direct the treatment of many elbow disorders. Biomechanical studies are required to develop and validate the optimal treatment of elbow disorders prior to their application in patients. Clinically relevant simulation of elbow motion in the laboratory can be a powerful tool to advance our knowledge of elbow disorders. This work was undertaken with the rationale that simulation and quantification of elbow motion could be improved significantly. This treatise includes the development and evaluation of …