Publications & Reports

(131 - 140) of 211    Prev | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | Next

Polyethylene Wear Debris and Long-Term Clinical Failure of the Charite Disc Prosthesis

Researchers assessed the clinical significance of polyethylene wear debris in salvage surgery after initial total disc replacement, the pattern and the mechanisms of polyethylene wear in the retrieved cores, and the extent of polyethylene debris in the periprosthetic tissues obtained from 4 patients. All of the retrieved polyethylene cores showed evidence of wear, but the extent and severity varied among the 4 patients. Histologic examination of the periprosthetic tissues confirmed the presence of wear debris lying in inflammatory fibrous tissue.

VIEW DETAILS

Anisotropy and Oxidative Resistance of Highly Crosslinked UHMWPE after Deformation Processing

Solid-state deformation processing is a promising technique for modifying the physical and mechanical properties of highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) beyond simple thermal treatment cycles that have been employed previously. This study evaluates anisotropy and oxidative resistance in a novel, radiation crosslinked (50kGy) UHMWPE material, incorporating solid-state, deformation processing by extrusion below the melt transition for application in total hip arthroplasty.

VIEW DETAILS

Significance of In Vivo Degradation for Polyethylene in Total Hip Arthroplasty

An implant retrieval program was developed to study in vivo degradation of polyethylene. Data from historical, ArCom, and Crossfire retrievals all pointed to a similar scenario in which the femoral head limits the in vivo oxidation of polyethylene at the bearing surface. Researchers concluded that in vivo degradation should be included among the list of potential long-term failure modes for modular polyethylene components for total hip arthroplasty.

VIEW DETAILS

Digital Photogrammetry for Quantitative Wear Analysis of Retrieved TKA Components

Researchers at Drexel University developed a digital photogrammetric method to quantify the extent of surface damage in retrieved total knee replacement components. The overall accuracy of area measurements was 97.8%. The photogrammetry method was found to be reasonably accurate and repeatable in measuring 2-D areas and applicable to determining wear. There was no significant variation in uncertainty detected among different implant designs.

VIEW DETAILS

Desgaste del polietileno y fractura del borde en la artroplastía total de disco

El propósito de este estudio fue evaluar la magnitud y tasa del desgaste del polietileno (PE) y daño superficial en los reemplazos totales de disco. Se analizaron veintiún implantes (SB CHARITÉ III: DePuy Spine, Raynham, MA) de 18 pacientes a los que se les realizaron cirugías de rectificación de reemplazos totales de disco. El mecanismo de desgaste dominante fue desgaste adhesivo/abrasivo tanto en el domo como en el borde. Éste es el primer estudio que analiza cuantitativamente los mecanismos de daño de largo plazo en reemplazos totales de disco contemporáneos. Los reemplazos totales de disco presentaron el tipo de daño superficial que se había observado previamente en los reemplazos de cadera y rodilla.

VIEW DETAILS

Oxidation behavior in prosthetic UHMWPE components sterilised with high energy radiation in the presence of oxygen

In the present study, a large number of never implanted, gamma sterilised prosthetic components have been analysed by using FTIR micro-spectroscopy and derivatisation techniques. Based on the obtained oxidation profiles, the samples were divided in three groups and a correlation between the oxidation products and distribution and some sterilisation parameters has been proposed. Presence of oxygen, dose rate and temperature were found to play a highly relevant role in determining the whole oxidation degree and its distribution in the UHMWPE components.

VIEW DETAILS

Book Chapter Excerpt: Total Disc Arthroplasty

The state of knowledge in total disc replacements is evolving rapidly. In this field, the majority of published papers are either clinical studies or review articles. This excerpt from the Spine Technology Handbook reviews and examines the previous (and soon to be realized) published technologies behind total disc arthroplasty from a bioengineering perspective. This chapter includes the history and background of CHARITÉ and ProDisc total disc replacements, which both incorporate UHMWPE as a bearing component.

VIEW DETAILS

Polyethylene Wear and Rim Fracture in Total Disc Arthroplasty

The purpose of this study was to evaluate the magnitude and rate of polyethylene (PE) wear and surface damage in TDRs. Twenty-one implants (SB CHARITÉ III: DePuy Spine, Raynham, MA) were analyzed from 18 patients undergoing TDR revision surgery. The dominant wear mechanism was adhesive/abrasive wear at both the dome and rim. This is the first study to quantitatively analyze the long-term PE damage mechanisms in contemporary TDRs. The TDRs displayed surface damage observed previously in both hip and knee replacements.

VIEW DETAILS

Frecuencia de artroplastías totales de cadera y de rodilla primarias y de rectificación en Estados Unidos

El propósito de este estudio fue cuantificar la tasa de procedimientos y la carga de rectificaciones correspondientes a las artroplastías totales de cadera y de rodilla en Estados Unidos. La cantidad y frecuencia de los procedimientos primarios de reemplazo de cadera y de rodilla aumentaron substancialmente entre 1990 y 2002, pero la tendencia fue considerablemente más pronunciada para la artroplastía primaria total de rodilla. Las tendencias de frecuencia informadas tienen importantes ramificaciones en la cantidad prevista de cirugías de reemplazo de articulaciones que realizarán los cirujanos ortopédicos en el futuro.

VIEW DETAILS

An Advanced User Material Model for UHMWPE

This report summarizes the finite element implementation of the Hybrid Model for UHMWPE as a user-material model in LS-DYNA (http://www.lsdyna.com/). The HM was calibrated to data from uniaxial tension experiments performed at different strain rates and with different loading-unloading segments. For validation, the calibrated HM was then used to simulate a small punch test. A direct comparison between the experimental data and model predictions of the calibration and validation data demonstrate that the HM accurately captures the non-linear response of UHMWPE. The ability to simulate large-scale contact problems was examined by simulating the deformation behavior of a total knee replacement component and the Charité™ artificial disc.

VIEW DETAILS