Effect of the design parameters on the in vitro wear performance of total shoulder arthroplasties

ABSTRACT Objective: To test in vitro and in vivo the wear performance of diamond-coated strips by means of tribological testing and scanning electronic microscope (SEM). Materials and Methods: To evaluate the in vitro wear performance, a tribological test was performed by a standard tribometer. The abrasive strips slid against stationary, freshly extracted premolars fixed in resin blocks, at a 2-newton load. At the end of the tribological test, the residual surface of the strip was observed by means of SEM analysis, which was performed every 50 meters until reaching 300 meters. For the in vivo analysis, the strip was used for 300 seconds, corresponding to 250 meters. Results: The strips presented a fenestrated structure characterized by diamond granules alternating with voids. After the first 50 meters, it was possible to observe tooth material deposited on the surface of the strips and a certain number of abrasive grains detached. The surface of the strip after 250 meters appeared smoother and therefore less effective in its abrasive power. After 300 seconds of in vivo utilization of the strip, it was possible to observe the detachment of diamond abrasive grains, the near absence of the grains and, therefore, loss of abrasive power. Conclusions: Under ideal conditions, after 5 minutes (300 meters) of use, the strip loses its abrasive capacity by about 60%. In vivo, a more rapid loss of abrasive power was observed due to the greater load applied by the clinician in forcing the strip into the contact point.

Download Full-text

Tuning the Properties of PNIPAm-Based Hydrogel Scaffolds for Cartilage Tissue Engineering

Polymers ◽

10.3390/polym13183154 ◽

2021 ◽

Vol 13 (18) ◽

pp. 3154

Author(s):

Md Mohosin Rana ◽

Hector De la Hoz Siegler

Keyword(s):

Tissue Engineering ◽

Physical Properties ◽

Tissue Regeneration ◽

Structural Integrity ◽

Cartilage Tissue ◽

Design Parameters ◽

Comprehensive Overview ◽

Hydrogel Scaffolds ◽

Design Variables

Poly(N-isopropylacrylamide) (PNIPAm) is a three-dimensional (3D) crosslinked polymer that can interact with human cells and play an important role in the development of tissue morphogenesis in both in vitro and in vivo conditions. PNIPAm-based scaffolds possess many desirable structural and physical properties required for tissue regeneration, but insufficient mechanical strength, biocompatibility, and biomimicry for tissue development remain obstacles for their application in tissue engineering. The structural integrity and physical properties of the hydrogels depend on the crosslinks formed between polymer chains during synthesis. A variety of design variables including crosslinker content, the combination of natural and synthetic polymers, and solvent type have been explored over the past decade to develop PNIPAm-based scaffolds with optimized properties suitable for tissue engineering applications. These design parameters have been implemented to provide hydrogel scaffolds with dynamic and spatially patterned cues that mimic the biological environment and guide the required cellular functions for cartilage tissue regeneration. The current advances on tuning the properties of PNIPAm-based scaffolds were searched for on Google Scholar, PubMed, and Web of Science. This review provides a comprehensive overview of the scaffolding properties of PNIPAm-based hydrogels and the effects of synthesis-solvent and crosslinking density on tuning these properties. Finally, the challenges and perspectives of considering these two design variables for developing PNIPAm-based scaffolds are outlined.

Download Full-text

The effect of design parameters of interspinous implants on kinematics and load bearing: an in vitro study

European Spine Journal ◽

10.1007/s00586-014-3237-7 ◽

2014 ◽

Vol 23 (4) ◽

pp. 762-771 ◽

Cited By ~ 6

Author(s):

Christoph Schilling ◽

M. Pfeiffer ◽

T. M. Grupp ◽

W. Blömer ◽

A. Rohlmann

Keyword(s):

In Vitro Study ◽

Vitro Study ◽

Design Parameters ◽

Load Bearing ◽

Interspinous Implants

Download Full-text

Hemodynamic influence of design parameters of novel venous valve prostheses

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2018-0037 ◽

2018 ◽

Vol 4 (1) ◽

pp. 149-151

Author(s):

Michael Stiehm ◽

Stefanie Kohse ◽

Kerstin Schümann ◽

Sebastian Kaule ◽

Stefan Siewert ◽

...

Keyword(s):

High Sensitivity ◽

Lower Limbs ◽

Hydrodynamic Performance ◽

Design Parameters ◽

Effective Orifice Area ◽

Valve Prosthesis ◽

Venous Valve ◽

Orifice Area ◽

Valve Prostheses

AbstractVenous ulcers of the lower limbs are one clinical manifestation of chronic venous insufficiency. Currently, there is no venous valve prosthesis available. This study presents novel venous valve prostheses made of threedimensional electrospun fibrous nonwoven leaflets. The aim of this study was to prove the feasibility of the manufacturing process as well as to investigate design features of the venous valve prostheses from a hemodynamic point of view. An adapted pulse duplicator system (ViVitrolabs, Victoria, BC, CA) was used for characterization of the hydrodynamic performance. For eight different venous valve prototypes flow rate, effective orifice area and regurgitation fraction was investigated in vitro. In particular, tricusp valve designs showed an up to 40% higher effective orifice area as well as 15% higher maximum flowrate compared to bicusp valve designs. However, the regurgitation fraction of the bicusp valve designs is up to 86% lower compared to tricusp valve. Additionally, the hemodynamic performance of the tricuspid valves showed a high sensitivity regarding the leaflet length. Bicuspid valves are less sensitive to changes of design parameters, more sufficient and therefore highly reliable.

Download Full-text

Glenoid bone grafting in primary anatomic total shoulder arthroplasty: a systematic review

Shoulder & Elbow ◽

10.1177/1758573220917653 ◽

2020 ◽

pp. 175857322091765

Author(s):

Betty Zhang ◽

Gavinn Niroopan ◽

Chetan Gohal ◽

Bashar Alolabi ◽

Timothy Leroux ◽

...

Keyword(s):

Bone Loss ◽

Shoulder Arthroplasty ◽

Bone Grafting ◽

Reverse Shoulder Arthroplasty ◽

Total Shoulder Arthroplasty ◽

Level Of Evidence ◽

Total Shoulder Arthroplasties ◽

Component Loosening ◽

Shoulder Arthroplasties

Background Primary anatomic total shoulder arthroplasty can be challenging in patients with complex glenoid wear patterns and bone loss. Severe retroversion (>15°) or significant bone loss may require bone grafting. This review summarizes the rate of revision and long-term outcomes of anatomic total shoulder arthroplasty with bone graft. Methods A systematic search of MEDLINE, Embase, PubMed, and CENTRAL databases was conducted from the date of inception to 23 October 2018. Two reviewers independently screened articles for eligibility and extracted data for analysis. The primary outcome was rate of revision. The secondary outcomes were rate of component loosening, functional outcome, and range of motion. Results Of the 1056 articles identified in the search, 26 underwent full-text screening and 7 articles were included in the analysis. All procedures were one-stage anatomic total shoulder arthroplasties. The rate of revision was 5.4% with component loosening and infection listed as indications over a weighted mean follow-up period of 6.3 years. Complications occurred in 12.6% of patients. Conclusion Glenoid bone grafting in anatomic total shoulder arthroplasty results in comparable revision rates and improvement in pain compared to augmented glenoid components and reverse shoulder arthroplasty. Due to the low quality of evidence, further prospective studies should be conducted. Level of evidence IV

Download Full-text

Anatomic versus reverse shoulder arthroplasty: a mid-term follow-up comparison

Shoulder & Elbow ◽

10.1177/1758573220921150 ◽

2020 ◽

pp. 175857322092115

Author(s):

Bradley S Schoch ◽

Joseph J King ◽

Joseph Zuckerman ◽

Thomas W Wright ◽

Chris Roche ◽

...

Keyword(s):

Shoulder Arthroplasty ◽

Patient Reported Outcomes ◽

External Rotation ◽

Reverse Shoulder Arthroplasty ◽

Total Shoulder Arthroplasty ◽

Reoperation Rate ◽

Patient Reported ◽

Total Shoulder Arthroplasties ◽

Shoulder Arthroplasties

Background Anatomic total shoulder arthroplasty improves pain and function with a reported reoperation rate of approximately 1% per year. With improved glenoid fixation, reverse shoulder arthroplasty implants may outperform anatomic total shoulder arthroplasty. We evaluate the functional outcomes and reoperation rate of anatomic total shoulder arthroplasty versus reverse shoulder arthroplasty at a minimum eight-year follow-up or revision. Methods Between 2005 and 2010, 187 shoulders (137 anatomic total shoulder arthroplasty, 50 reverse shoulder arthroplasty) were retrospectively reviewed at a mean of 8.8 years. The mean age at surgery was 67 years. Females were more commonly treated with reverse shoulder arthroplasty. Both groups had similar body mass index and comorbidities. Outcome measures evaluated included abduction, forward elevation, external rotation, internal rotation, Simple Shoulder Test, Constant score, American Shoulder and Elbow Score, University of California Los Angeles Shoulder score, and Shoulder Pain and Disability Index. Results At follow-up, anatomic total shoulder arthroplasty demonstrated greater overhead range of motion and external rotation. All patient-reported outcomes remained similar between groups. Reverse shoulder arthroplasty patients were more likely to rate shoulders as much better or better after surgery (90% versus 67%, p = 0.004). Complications were observed in 24% of anatomic total shoulder arthroplasties and 8% of reverse shoulder arthroplasties (p = 0.02). Reoperation was more common in anatomic total shoulder arthroplasties (23% versus 4%, p = 0.003). Discussion At mid-to-long-term follow-up, reverse shoulder arthroplasties demonstrated significantly fewer complications and reoperations than anatomic total shoulder arthroplasties. Despite similar patient-reported outcomes, reverse shoulder arthroplasty patients were more likely to be satisfied with their shoulder.

Download Full-text

New Approach Methods to Evaluate Health Risks of Air Pollutants: Critical Design Considerations for In Vitro Exposure Testing

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17062124 ◽

2020 ◽

Vol 17 (6) ◽

pp. 2124 ◽

Cited By ~ 4

Author(s):

Jose Zavala ◽

Anastasia N. Freedman ◽

John T. Szilagyi ◽

Ilona Jaspers ◽

John F. Wambaugh ◽

...

Keyword(s):

Air Pollution ◽

Lessons Learned ◽

Air Pollutant ◽

In Vivo Studies ◽

Design Parameters ◽

Vast Number ◽

New Approach ◽

In Vitro Exposure

Air pollution consists of highly variable and complex mixtures recognized as major contributors to morbidity and mortality worldwide. The vast number of chemicals, coupled with limitations surrounding epidemiological and animal studies, has necessitated the development of new approach methods (NAMs) to evaluate air pollution toxicity. These alternative approaches include in vitro (cell-based) models, wherein toxicity of test atmospheres can be evaluated with increased efficiency compared to in vivo studies. In vitro exposure systems have recently been developed with the goal of evaluating air pollutant-induced toxicity; though the specific design parameters implemented in these NAMs-based studies remain in flux. This review aims to outline important design parameters to consider when using in vitro methods to evaluate air pollutant toxicity, with the goal of providing increased accuracy, reproducibility, and effectiveness when incorporating in vitro data into human health evaluations. This review is unique in that experimental considerations and lessons learned are provided, as gathered from first-hand experience developing and testing in vitro models coupled to exposure systems. Reviewed design aspects include cell models, cell exposure conditions, exposure chambers, and toxicity endpoints. Strategies are also discussed to incorporate in vitro findings into the context of in vivo toxicity and overall risk assessment.

Download Full-text

Electromyographic analysis of reverse total shoulder arthroplasties

Journal of Shoulder and Elbow Surgery ◽

10.1016/j.jse.2013.05.005 ◽

2014 ◽

Vol 23 (2) ◽

pp. 166-172 ◽

Cited By ~ 22

Author(s):

David Walker ◽

Thomas W. Wright ◽

Scott A. Banks ◽

Aimee M. Struk

Keyword(s):

Total Shoulder Arthroplasties ◽

Electromyographic Analysis ◽

Shoulder Arthroplasties ◽

Reverse Total Shoulder

Download Full-text

Effect of Implant Shape and Material Properties on Stresses in the Glenoid Components of Total Shoulder Arthroplasties: A Finite Element Analysis

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19494 ◽

2010 ◽

Cited By ~ 2

Author(s):

Jingzhou Zhang ◽

Charlie Yongpravat ◽

Marc D. Dyrszka ◽

William N. Levine ◽

Thomas R. Gardner ◽

...

Keyword(s):

Humeral Head ◽

Glenohumeral Joint ◽

Total Shoulder Arthroplasty ◽

Peak Stress ◽

Glenoid Component ◽

Joint Stability ◽

Element Analysis ◽

Total Shoulder Arthroplasties ◽

Shoulder Arthroplasties ◽

Glenoid Loosening

The geometry of the glenohumeral joint is osseous, naturally nonconforming and minimally constrained, thus the essential requirement of a glenohumeral prosthesis in total shoulder arthroplasty (TSA) is prevention of joint degeneration and glenoid loosening. A variety of glenoid prostheses have been developed. Nonconforming glenohumeral implants are common for TSA. However, the nonconforming shape increases the instability when the humeral head is in the central region, where motion frequently occurs. Conforming implants can increase joint stability, but the “rocking-horse” effect [1] caused by the conforming shape is thought to lead to high stresses and moments at the glenoid rim when the humeral head approaches the periphery during its range of motion. The hybrid design, with a conforming center and a nonconforming periphery, combines the advantages of both nonconforming and conforming implant geometries. It has been shown [2] that the peak stress generated in glenoid components during activities of daily living can be as high as 25 MPa, which exceeds the polyethylene yield strength of the glenoid component and can lead to wear and cold flow of the component. Polyethylene has also been shown to be viscoelastic [3]. Therefore, both elastic-plastic and viscoelastic-plastic models of the glenoid implant were used to determine how viscoelasticity affected stress in the implant. The effects of implant shape on the stresses in the center, transition, and superior zones for the three different glenoid implant shapes, as well as on the stress in the underlying cement and bone, were determined in this study.

Download Full-text

Recent Progress in Microfluidic Models of the Blood-Brain Barrier

Micromachines ◽

10.3390/mi10060375 ◽

2019 ◽

Vol 10 (6) ◽

pp. 375 ◽

Cited By ~ 10

Author(s):

Lili Jiang ◽

Shu Li ◽

Junsong Zheng ◽

Yan Li ◽

Hui Huang

Keyword(s):

Blood Brain Barrier ◽

Pharmaceutical Research ◽

Experimental Models ◽

Brain Barrier ◽

Design Parameters ◽

Tight Junction Formation ◽

Blood Brain ◽

Micrometer Scale ◽

Physical And Chemical

The blood-brain barrier (BBB) is a critical physical and chemical barrier that maintains brain homeostasis. Researchers in academia and industry are highly motivated to develop experimental models that can accurately mimic the physiological characteristics of the BBB. Microfluidic systems, which manipulate fluids at the micrometer scale, are ideal tools for simulating the BBB microenvironment. In this review, we summarized the progress in the design and evaluation of microfluidic in vitro BBB models, including advances in chip materials, porous membranes, the use of endothelial cells, the importance of shear stress, the detection specific markers to monitor tight junction formation and integrity, measurements of TEER and permeability. We also pointed out several shortcomings of the current microfluidic models. The purpose of this paper is to let the readers understand the characteristics of different types of model design, and select appropriate design parameters according to the research needs, so as to obtain the best experimental results. We believe that the microfluidics BBB models will play an important role in neuroscience and pharmaceutical research.

Download Full-text