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Wannomae K.K.,Massachusetts General Hospital | Christensen S.D.,Massachusetts General Hospital | Micheli B.R.,Massachusetts General Hospital | Rowell S.L.,Massachusetts General Hospital | And 2 more authors.
Journal of Arthroplasty | Year: 2010

Wear and delamination of conventional ultrahigh-molecular-weight polyethylene (UHMWPE) components used in total knee arthroplasty can compromise long-term performance. Radiation cross-linking and melt-annealing reduced wear and increased delamination resistance of UHMWPE. An alternative material is the α-tocopherol-stabilized irradiated UHMWPE (αTPE), with improved mechanical and fatigue properties vs irradiated and melted UHMWPE. We studied the wear and delamination resistance of αTPE and conventional UHMWPE (direct compression molded GUR 1050 and Himont 1900) under reciprocating unidirectional motion. Wear resistance was improved, and no delamination was observed in αTPE. Accelerated aging did not alter the wear and delamination behavior of αTPE. The GUR 1050 UHMWPE showed delamination and pitting when subjected to unidirectional reciprocating motion after accelerated aging. Himont 1900 UHMWPE showed no delamination when subjected to unidirectional reciprocating motion after accelerated aging. α-Tocopherol-stabilized irradiated UHMWPE is advanced for use in total knee arthroplasty due to its high resistance to wear, delamination, and oxidation. © 2010 Elsevier Inc.

Pietrzak W.S.,Biomet Inc. | Pietrzak W.S.,University of Illinois at Chicago
Journal of Craniofacial Surgery | Year: 2010

Bioabsorbable devices are generally susceptible to some form of degradation or alteration of material properties in response to exposure to the terminal sterilization cycle. In addition to affecting the material strength, sterilization can also increase the rate of hydrolysis, both of which can impact clinical performance. The impact of sterilization on the material/device is unpredictable and must be empirically determined. This study examined the effects of ethylene oxide treatment on the material properties of LactoSorb 82:18 poly(l-lactic acid)-poly(glycolic acid) craniofacial plates. Compared with untreated control plates, there was no effect on the initial inherent viscosity (1.3 dL/g), the glass transition temperature (58°C), or on the flexural mechanical properties. Furthermore, there was no effect on the in vitro rate of hydrolysis and mechanical strength loss profile. This provides evidence that the ethylene oxide sterilization cycle is compatible with these copolymer plates and that such treatment should not affect the clinical performance. © 2010 by Mutaz B. Habal, MD.

Markova D.Z.,Thomas Jefferson University | Kepler C.K.,Thomas Jefferson University | Kepler C.K.,Rothman Institute | Addya S.,Thomas Jefferson University | And 9 more authors.
Arthritis Research and Therapy | Year: 2013

Introduction: Despite many advances in our understanding of the molecular basis of disc degeneration, there remains a paucity of preclinical models which can be used to study the biochemical and molecular events that drive disc degeneration, and the effects of potential therapeutic interventions. The goal of this study is to characterize global gene expression changes in a disc organ culture system that mimics early nontraumatic disc degeneration.Methods: To mimic a degenerative insult, rat intervertebral discs were cultured in the presence of TNF-α, IL-1β and serum-limiting conditions. Gene expression analysis was performed using a microarray to identify differential gene expression between experimental and control groups. Differential pattern of gene expression was confirmed using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) or Western blot.Results: Treatment resulted in significant changes in expression of more than 1,000 genes affecting many aspects of cell function including cellular movement, the cell cycle, cellular development, and cell death and proliferation. Many of the most highly upregulated and downregulated genes have known functions in disc degeneration and extracellular matrix hemostasis. Construction of gene networks based on known cellular pathways and expression data from our analysis demonstrated that the network associated with cell death, cell cycle regulation and DNA replication and repair was most heavily affected in this model of disc degeneration.Conclusions: This rat organ culture model uses cytokine exposure to induce wide gene expression changes with the most affected genes having known reported functions in disc degeneration. We propose that this model is a valuable tool to study the etiology of disc degeneration and evaluate potential therapeutic treatments. © 2013 Markova et al.; licensee BioMed Central Ltd.

Freedman J.,Biomet Inc.
Annual Technical Conference - ANTEC, Conference Proceedings | Year: 2011

In this paper, highly crosslinked and vitamin E infused (VITE) ultra-high molecular weight polyethylene is evaluated for mechanical properties, oxidation resistance, and wear. Testing included small punch mechanical properties, impact strength, a fatigue study, and knee wear simulator testing. The VITE material showed no evidence of oxidation and no decrease in the mechanical properties with accelerated aging. The VITE material showed an 86% reduction in wear over the control. The combination of crosslinking and vitamin E infusion produced a polyethylene material with improved wear properties and superior oxidation resistance suitable for use in orthopedic applications.

Sundararaj S.K.C.,University of Kentucky | Cieply R.D.,University of Kentucky | Gupta G.,University of Kentucky | Gupta G.,Biomet Inc. | And 2 more authors.
Journal of Tissue Engineering and Regenerative Medicine | Year: 2015

Growth plate fracture can lead to retarded growth and unequal limb length, which may have a lifelong effect on a person's physical stature. The goal of this research was to develop an in vivo tissue-engineering approach for the treatment of growth plate injury via localized delivery of insulin-like growth factor I (IGF-I) from cell-free poly(lactic-co-glycolic acid) (PLGA) scaffolds. Mass loss and drug release studies were conducted to study the scaffold degradation and IGF-I release patterns. In vitro cell studies showed that rat bone marrow stromal cells seeded on the porous scaffolds colonized the pores and deposited matrix within the scaffolds. These in vitro evaluations were followed by a proof-of-concept animal study involving implantation of scaffolds in proximal tibial growth plate defects in New Zealand white rabbits. Histological analysis of tissue sections from the in vivo studies showed regeneration of cartilage, albeit with disorganized structure, at the site of implantation of IGF-I-releasing scaffolds; in contrast, only bone was formed in empty defects and those treated with IGF-free scaffolds. The present findings show the potential for treating growth plate injury using in vivo tissue engineering techniques. Copyright © 2015 John Wiley & Sons, Ltd.

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