10 research outputs found
In Vivo Performance of the Femoral Head-Neck Taper Connection and Development of an Electrochemical Framework for Quantitative Corrosion Investigations
No full textCorrosion at the modular head-neck connection in total hip arthroplasty has been shown to have deleterious biological consequences, and recent clinical observations have postulated that it may compromise the integrity of the taper connection. This dissertation summarizes the patient demographics, clinical details, and design variables of hip implants that were examined to understand their impact on the in vivo performance of taper junctions. Furthermore, it describes electrochemical assessment methods that were developed to quantitatively evaluate the effects of corrosion phenomena. In vivo taper performance was assessed using femoral components retrieved from revision surgery and from cadaveric donors. Preliminary time-to-event analyses were conducted on a collection of 5,821 retrieved joint prostheses, identifying risks factors for infection consistent with the findings of administrative databases and implant registries. The role of an activated immune system on corrosion at the head-neck taper was then explored with a subset of these explants. The results did not indicate more severe corrosion for devices revised with infection, but suggested greater corrosion severity for devices that were implanted in male patients and during primary arthroplasty procedures. Multivariable analysis of clinical and design variables did not identify an association between corrosion and the size of the modular taper, but found increased corrosion for heavier patients, longer implantation times, greater femoral head offsets and tapers with a lower flexural rigidity. Mechanical assessment of taper connection strength demonstrated that more severely corroded stem trunnions were associated with stronger taper connections. Additionally, greater corrosion was observed on retrievals from revision surgery than on those from cadaveric donors. In consideration of the electrochemical nature of corrosion processes, a new framework was devised to overcome limitations of visual corrosion assessments. Analysis using electrochemical impedance spectroscopy identified decreased impedance and increased constant phase element (CPE) capacitance as the strongest predictors of increased corrosion severity. Additionally, lower values for impedance phase angle, CPE-exponent and polarization resistance were associated with increased corrosion. From microscopic and metallographic inspection, it was found that components with subsurface damage features had significantly higher capacitance and lower impedance values than those only exhibiting surface corrosion damage features. Given that the surface area of an electrode is inversely proportional to its impedance and directly proportional to its capacitance, electrochemical analyses may provide an opportunity to identify penetrative corrosion features without destructive metallographic evaluation.Ph.D., Biomedical Engineering -- Drexel University, 201
Oxidation, Damage Mechanisms, and Reasons for Revision of Sequentially Annealed Highly Crosslinked Polyethylene in Total Knee Arthroplasty
No full textRetrieval analysis of PEEK rods for posterior fusion and motion preservation
No full textIntroductionThe purpose of this study was to analyze explanted PEEK rod spinal systems in the context of their clinical indications. We evaluated damage to the implant and histological changes in explanted periprosthetic tissues.Methods12 patients implanted with 23 PEEK rods were revised between 2008 and 2012. PEEK rods were of the same design (CD Horizon Legacy, Medtronic, Memphis TN, USA). Retrieved components were assessed for surface damage mechanisms, including plastic deformation, scratching, burnishing, and fracture. Patient history and indications for PEEK rod implantation were obtained from analysis of the medical records.Results11/12 PEEK rod systems were employed for fusion at one level, and motion preservation at the adjacent level. Surgical complications in the PEEK cohort included a small dural tear in one case that was immediately repaired. There were no cases of PEEK rod fracture or pedicle screw fracture. Retrieved PEEK rods exhibited scratching, as well as impressions from the set screws and pedicle screw saddles. PEEK debris was observed in two patient tissues, which were located adjacent to PEEK rods with evidence of scratching and burnishing.ConclusionThis study documents the surface changes and tissue reactions for retrieved PEEK rod stabilization systems. Permanent indentations by the set screws and pedicle screws were the most prevalent observations on the surface of explanted PEEK rods
Trunnion Failure of the Recalled Low Friction Ion Treatment Cobalt Chromium Alloy Femoral Head
No full text<i>Technical Note:</i>Is Corrosion a Threat to the Strength of the Taper Connection in Femoral Components of Total Hip Replacements?
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Microgrooved Surface Topography Does Not Influence Fretting Corrosion of Tapers in Total Hip Arthroplasty: Classification and Retrieval Analysis
No full textDoes Taper Size Have an Effect on Taper Damage in Retrieved Metal-on-Polyethylene Total Hip Devices?
No full textAbstractBackgroundTaper design has been identified as a possible contributor to fretting corrosion damage at modular connections in total hip arthroplasty systems, but variations in as-manufactured taper interfaces may confound this analysis. This study characterized taper damage in retrievals with 2 different taper sizes but comparable taper surface finishes and investigated if fretting and corrosion damage is related to taper size in the context of a multivariable analysis for metal-on-polyethylene bearings.MethodsA total of 252 cobalt chromium femoral heads were identified in a collection of retrievals: 77 with taper A and 175 with taper B. Implantation time averaged 5.4 ± 6.0 years (range, 0-26 years). Explants were cleaned and analyzed using a 4-point semiquantitative method. Clinical and device factors related to head taper fretting corrosion damage were assessed using ordinal logistic regression with forward stepwise control. Components were then selected to create 2 balanced cohorts, matched on significant variables from the multivariable analysis.ResultsIncreased head offset (P < .001), longer implantation time (P = .002), heavier patients (P < .001), and more flexible tapers (P < .001) were associated with increased taper fretting and corrosion damage. When damage scores were compared between the balanced groups, no significant differences were found.ConclusionThese results suggest that fretting and corrosion damage is insensitive to differences in taper size. The final model derived explains almost half of the fretting corrosion damage observed and identifies contributing factors that are consistent with other in vitro and retrieval studies
