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Pierce T.P.,Rubin Institute for Advanced Orthopedics | Jauregui J.J.,Rubin Institute for Advanced Orthopedics | Cherian J.J.,Rubin Institute for Advanced Orthopedics | Elmallah R.D.K.,Rubin Institute for Advanced Orthopedics | And 2 more authors.
HIP International | Year: 2015

Purpose: Cementless press-fit total hip arthroplasty (THA) with the Accolade stem (Stryker Accolade™TMZF, Mahwah, New Jersey) has demonstrated variable implant survivorship and outcomes. The purpose of this study was to analyse the: 1) implant survivorship; 2) complications; 3) functional outcomes; 4) overall quality of life; and 5) patient expectations and satisfaction following THA with this particular press-fit stem. Methods: A prospectively collected database of 222 patients who underwent THA at 7 institutions between 2006 and 2009 using the Accolade stem (Stryker Inc. Mahwah, New Jersey) was evaluated. Harris Hip Score (HHS) and SF-12 were used to assess the outcomes at 2- and 5-year follow-up. Kaplan-Meier survivorship was calculated at 5 years of follow-up. Results: The 5-year aseptic and all-cause survivorship rates were 99.4% (95% CI, 96.3 to 99.9%) and 97.9% (95% CI, 94.6 to 99.2%), respectively. At 2 and 5 years postoperatively, the patients demonstrated a mean HHS of approximately 89 points and 92 points, respectively. The mental and physical components of the SF-12 mean score increased with the physical component having a more marked increase. The mental and physical components of the SF-12 score increased to a mean of 46 and 45 points at 2 and 5 years, respectively. At 2-year follow-up, over 90% of patients were satisfied with their outcome in a majority of areas surveyed. Discussion: Our results suggest that the use of this press-fit construct results in tremendous improvements in functional and quality of life outcomes, along with excellent survivorship at short- and mid-term follow-up. © 2015 Wichtig Publishing. Source

Lewallen E.A.,Mayo Medical School | Jones D.L.,Mayo Medical School | Dudakovic A.,Mayo Medical School | Thaler R.,Mayo Medical School | And 8 more authors.
Gene | Year: 2016

Integration of porous metal prosthetics, which restore form and function of irreversibly damaged joints, into remaining healthy bone is critical for implant success. We investigated the biological properties of adipose-tissue-derived mesenchymal stromal/stem cells (AMSCs) and addressed their potential to alter the in vitro microenvironment of implants. We employed human AMSCs as a practical source for musculoskeletal applications because these cells can be obtained in large quantities, are multipotent, and have trophic paracrine functions. AMSCs were cultured on surgical-grade porous titanium disks as a model for orthopedic implants. We monitored cell/substrate attachment, cell proliferation, multipotency, and differentiation phenotypes of AMSCs upon osteogenic induction. High-resolution scanning electron microscopy and histology revealed that AMSCs adhere to the porous metallic surface. Compared to standard tissue culture plastic, AMSCs grown in the porous titanium microenvironment showed differences in temporal expression for genes involved in cell cycle progression (CCNB2, HIST2H4), extracellular matrix production (COL1A1, COL3A1), mesenchymal lineage identity (ACTA2, CD248, CD44), osteoblastic transcription factors (DLX3, DLX5, ID3), and epigenetic regulators (EZH1, EZH2). We conclude that metal orthopedic implants can be effectively seeded with clinical-grade stem/stromal cells to create a pre-conditioned implant. © 2016 Elsevier B.V. Source

Swaminathan V.,Syracuse Biomaterials Institute | Zeng H.,Stryker Orthopedics | Lawrynowicz D.,Stryker Orthopedics | Zhang Z.,Stryker Orthopedics | Gilbert J.L.,Syracuse Biomaterials Institute
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2011

Hard coatings for articulating surfaces of total joint replacements may improve the overall wear resistance. However, any coating approach must take account of changes in corrosion behavior. This preliminary assessment analyzes the corrosion kinetics, impedance and mechanical-electrochemical stability of 100 μm thick plasma sprayed chromium oxide (Cr 2O 3) coatings on bearing surfaces in comparison to the native alloy oxide films on Co-Cr-Mo and Ti-6Al-6V. Cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and mechanical abrasion under potentiostatic conditions were performed on coated and substrate surfaces in physiological saline. SEM analysis characterized the coating morphology. The results showed that the corrosion current density values of chromium oxide coatings (0.4-1.2 μA/cm 2) were of the same order of magnitude as Ti-6Al-4V alloy. Mechanical abrasion did not increase corrosion rates of chromium oxide coatings but did for uncoated Co-Cr-Mo and Ti-6Al-4V. The impedance response of chromium oxide coatings was very different than Co-Cr-Mo and Ti-6Al-4V native oxides characterized by a defected coating model. More of a frequency-independent purely resistive response was seen in mid-frequency range for the coatings (CPE coat: 40-280 nF/cm 2 (rad/s) 1-α, α: 0.67-0.83) whereas a more capacitive character is seen for Co-Cr-Mo and Ti-6Al-4V (CPE ox around 20 μF/cm 2 (rad/s) 1-α, α around 0.9). Pores, interparticle gaps and incomplete fusion typical for thermal spray coatings were present in these oxides which could have influenced corrosion resistance. The coating microstructure could have allowed some fluid penetration. Overall, these coatings appear to have suitable corrosion properties for wear surfaces © 2011 Wiley Periodicals, Inc. Source

Swaminathan V.,Syracuse University | Swaminathan V.,Syracuse Biomaterials Institute | Zeng H.,Stryker Orthopedics | Lawrynowicz D.,Stryker Orthopedics | And 3 more authors.
Electrochimica Acta | Year: 2012

This study investigated the electrochemical behavior of chromium nano-carbide cermet coating applied on Ti-6Al-4V and Co-Cr-Mo alloys for potential application as wear and corrosion resistant bearing surfaces. The cermet coating consisted of a highly heterogeneous combination of carbides embedded in a metal matrix. The main factors studied were the effect of substrate (Ti-6Al-4V vs. Co-Cr-Mo), solution conditions (physiological vs. 1 M H 2O 2 of pH 2), time of immersion (1 vs. 24 h) and post coating treatments (passivation and gamma sterilization). The coatings were produced with high velocity oxygen fuel (HVOF) thermal spray technique at atmospheric conditions to a thickness of 250 μm then ground and polished to a finished thickness of 100 μm and gamma sterilized. Native Ti-6Al-4V and Co-Cr-Mo alloys were used as controls. The corrosion behavior was evaluated using potentiodynamic polarization, mechanical abrasion and electrochemical impedance spectroscopy under physiologically representative test solution conditions (phosphate buffered saline, pH 7.4, 37°C) as well as harsh corrosion environments (pH ∼ 2, 1 M H 2O 2, T = 65°C). Severe environmental conditions were used to assess how susceptible coatings are to conditions that derive from possible crevice-like environments, and the presence of inflammatory species like H 2O 2. SEM analysis was performed on the coating surface and cross-section. The results show that the corrosion current values of the coatings (0.4-4 μA/cm 2) were in a range similar to Co-Cr-Mo alloy. The heterogeneous microstructure of the coating influenced the corrosion performance. It was observed that the coating impedances for all groups decreased significantly in aggressive environments compared with neutral and also dropped over exposure time. The low frequency impedances of coatings were lower than controls. Among the coated samples, passivated nanocarbide coating on Co-Cr-Mo alloy displayed the least corrosion resistance. However, all the coated materials demonstrated higher corrosion resistance to mechanical abrasion compared to the native alloys. © 2011 Elsevier Ltd. All Rights Reserved. Source

Mullen L.,University of Liverpool | Stamp R.C.,University of Liverpool | Fox P.,University of Liverpool | Jones E.,Stryker Orthopedics | And 2 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2010

In this study, the unit cell approach, which has previously been demonstrated as a method of manufacturing porous components suitable for use as orthopedic implants, has been further developed to include randomized structures. These random structures may aid the bone in-growth process because of their similarity in appearance to trabecular bone and are shown to carry legacy properties that can be related back to the original unit cell on which they are ultimately based. In addition to this, it has been shown that randomization improves the mechanical properties of regular unit cell structures, resulting in anticipated improvements to both implant functionality and longevity. The study also evaluates the effect that a post process sinter cycle has on the components, outlines the improved mechanical properties that are attainable, and also the changes in both the macro and microstructure that occur. © 2009 Wiley Periodicals, Inc. Source

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