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Western Journal of Surgery, Obstetrics,... Feb 1949
Topics: Anesthesia, Spinal; Humans; Polyethylene; Polyethylenes
PubMed: 18111808
DOI: No ID Found -
The International Journal of Applied... Feb 1963
Topics: Manufactured Materials; Polyethylene; Polyethylenes; Radiometry; Spectrum Analysis
PubMed: 13973100
DOI: 10.1016/0020-708x(63)90098-x -
Stain Technology Jan 1955
Topics: Coloring Agents; Histological Techniques; Histology; Polyethylene; Polyethylenes; Staining and Labeling
PubMed: 13225983
DOI: No ID Found -
Acta Biomaterialia Sep 2011The lifetime of total joint replacement prostheses utilizing ultrahigh-molecular-weight polyethylene (UHMWPE) components has historically been determined by their wear...
The lifetime of total joint replacement prostheses utilizing ultrahigh-molecular-weight polyethylene (UHMWPE) components has historically been determined by their wear resistance. It has been discovered that radiation crosslinking of UHMWPE can substantially increase its wear resistance. However, it is also well recognized that there is a radiation-dose-dependent decrease in several important mechanical properties of UHMWPE, such as fracture toughness and resistance to fatigue crack propagation. In this study, the effect of radiation crosslinking (followed by remelting) on the morphology, tensile properties and wear resistance of UHMWPE was investigated. Wear tests were conducted against both the commonly used cobalt-chromium counterface polished to implant grade smoothness as well as a smoother ceramic (alumina) counterface. The results showed that 50kGy dose radiation crosslinking increased the wear resistance of UHMWPE against the cobalt-chromium counterface 7-fold, but the coupling of remelted, crosslinked UHMWPE against the smoother alumina counterface led to a 20-fold increase in wear resistance. This study shows that the use of an alumina counterface would circumvent the need to use a high radiation dose in crosslinking UHMWPE, associated with poor mechanical properties, without compromising wear resistance.
Topics: Aluminum Oxide; Biocompatible Materials; Ceramics; Materials Testing; Molecular Weight; Polyethylene; Prostheses and Implants
PubMed: 21640855
DOI: 10.1016/j.actbio.2011.05.018 -
Journal of Biomedical Materials... Nov 2007Wear performance and mechanical properties of cross-linking polyethylene (XLPE) tibial inserts were investigated using a knee simulator, scanning electron microscopy...
Wear performance and mechanical properties of cross-linking polyethylene (XLPE) tibial inserts were investigated using a knee simulator, scanning electron microscopy (SEM), and a small punch test (SPT). Ultrahigh molecular weight PE made from GUR1050 resin was irradiated at doses ranging from 0 to 200 kGy and then machined into tibial inserts followed by annealing. The knee simulator was run for up to four million cycles. As the radiation dose increased from 0 to 100 kGy, the wear rate decreased dramatically, yielding 95% wear reduction at 100 kGy. The microwear features observed by SEM supported the dose-dependent wear reduction. The SPT for XLPE after the simulation test showed that, as the radiation dose increased from 0 to 200 kGy, the ultimate displacement decreased dose-dependently, while the ultimate load increased from 0 to 75 kGy and decreased from 75 to 200 kGy. The resulting toughness of the PE increased to its maximum at a dose of 50 kGy and then decreased with higher doses up to 200 kGy. PE cross-linked with radiation doses from 25 to 75 kGy had greater toughness than virgin, nonirradiated PE. However, PE irradiated with 100 kGy or more had lower toughness than virgin PE. These data suggest that a certain amount of irradiation enhances both wear performance and toughness of PE tibial inserts. Although a certain amount of cross-linking would be effective for clinical application of PE tibial inserts, an optimal radiation dose should be much smaller than that used in current XLPE in total hip arthroplasty.
Topics: Acrylic Resins; Arthroplasty, Replacement, Knee; Biomechanical Phenomena; Cross-Linking Reagents; Dose-Response Relationship, Drug; Humans; Knee Joint; Polyethylene; Tibia
PubMed: 17471519
DOI: 10.1002/jbm.b.30835 -
Acta Biomaterialia Sep 2009Periprosthetic osteolysis is one of the main reasons for revision of arthroplasty. The osteolytic reaction is influenced by the dose, size and shape of the wear...
Periprosthetic osteolysis is one of the main reasons for revision of arthroplasty. The osteolytic reaction is influenced by the dose, size and shape of the wear particles. For arthroplasty, a low number and biologically less active particles are required. This is the first study which analyzes the impact of different knee designs, combined with crosslinked polyethylenes (sequentially irradiated and annealed as well as remelted techniques), on the amount, size and shape of particles. Overall, six material combinations, four of them with crosslinked polyethylene (XPE) and two of them with ultra-high molecular weight polyethylene (UHMWPE) inserts, including fixed and mobile bearings, were tested in a knee joint simulator. After isolation nearly 100,000 particles were analyzed in size, shape and number by scanning electron microscopy and image analysis. For all the designs, the wear was predominantly smooth and granular with few fibrillar particles. The Scorpio design with the X3 insert, the Natural Knee II design with the Durasul insert and the LCS design, also combined with a crosslinked polyethylene insert, generated statistically significant (P<0.05) lower particle numbers. The particle size was independent of the radiation dose. The wear generated by the LCS knee design (XPE and UHMWPE) had a higher percentage fraction of particles >1microm in size (equivalent circle diameter). The NexGen design, tested with the Prolong insert, showed a high number of particles in the biologically active size range compared with the other crosslinked designs, which could be a predictor for higher biological reactivity.
Topics: Biocompatible Materials; Equipment Failure Analysis; Knee Prosthesis; Materials Testing; Particle Size; Polyethylene; Prosthesis Design
PubMed: 19375997
DOI: 10.1016/j.actbio.2009.03.016 -
Journal of Hazardous Materials Jun 2007The thermal fast pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor in the 450-715 degrees C range, and individual...
The thermal fast pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor in the 450-715 degrees C range, and individual products have been monitored with the aim of obtaining kinetic data for the design and simulation of this process at large scale. Kinetic schemes have been proposed in order to explain both the results obtained in the laboratory plant and those obtained in the literature by other authors operating at laboratory and larger scale. Discrimination has been carried out based on the contribution of the variance of model parameters (stepwise regression) to the total variance explained by the model. The models based on that of Westerhout et al. [R.W.J. Westerhout, J. Waanders, W.P.M. Van Swaaij, Recycling of polyethene and polypropene in a novel bench-scale rotating cone reactor by high-temperature pyrolysis. Ind. Eng. Chem. Res. 37 (6) (1998) 2293-2300] do not adequately predict the experimental results, especially those corresponding to aromatics and char, which is probably due to the very short residence times attained in the conical spouted bed and, consequently, to the lower yields of aromatics and char. The model of best fit is the one where polyethylene degrades to give gas, liquid (oil) and wax fractions. Furthermore, the latter undergoes secondary reactions to give liquid and aromatics, which in turn produce more char.
Topics: Hot Temperature; Kinetics; Models, Chemical; Polyethylene
PubMed: 17337118
DOI: 10.1016/j.jhazmat.2007.01.101 -
Clinical Biomechanics (Bristol, Avon) May 2009Suture knots used in tendon surgery must be strong but small enough so that they do not hinder gliding. For this purpose, we devised a unique "antislip" knot.
BACKGROUND
Suture knots used in tendon surgery must be strong but small enough so that they do not hinder gliding. For this purpose, we devised a unique "antislip" knot.
METHODS
Three suture materials were used: Ethibond, Fiberwire, and Nespron. They were tied with either the antislip knot using a pair of United States Pharmacopeia (USP) 2 sutures or with a conventional reef knot using USP2 single sutures. The volume and tensile strength of the knots were measured (n = 25 for each combination of suture and method).
FINDINGS
The maximum tensile strength was observed with Fiberwire antislip knots with five throws (mean 587 N) and six throws (mean 590 N), and Nespron antislip knots with five throws (mean 554 N) and six throws (mean 552 N); no significant differences were found among the four knots. Tensile strength per volume showed maximum values with Fiberwire antislip knots with four throws (mean 17.4 N/microl) and five throws (mean 16.8 N/microl), and Nespron antislip knots with four throws (mean 17.6 N/microl) and five throws (mean 16.8N/microl), which were not significantly different and were over 1.25-fold greater than the value for a reef knot. Ethibond had less tensile strength than Fiberwire and Nespron.
INTERPRETATION
The antislip knot is smaller for the same or greater strength than a conventional reef knot. The 4- or 5-throw antislip knot was most effective for slippery polyethylene sutures such as Fiberwire and Nespron. The antislip knot should improve biological healing of repaired tendons through accelerated rehabilitation.
Topics: Biomechanical Phenomena; Equipment Design; Humans; Materials Testing; Polyethylene; Polyethylenes; Suture Techniques; Sutures; Tendons; Tensile Strength; Weight-Bearing
PubMed: 19261363
DOI: 10.1016/j.clinbiomech.2009.01.013 -
Clinical Orthopaedics and Related... Nov 2002Recently, highly cross-linked polyethylenes with high wear and oxidation resistance have been developed. These materials may improve the in vivo performance of...
Recently, highly cross-linked polyethylenes with high wear and oxidation resistance have been developed. These materials may improve the in vivo performance of polyethylene components used in total knee arthroplasty. To date, the in vitro knee wear testing of these new polyethylenes has been done under conditions of normal gait. However, their critical assessment also must include aggressive in vitro fatigue and wear testing. In the current study, an aggressive in vitro knee wear and device fatigue model simulating a tight posterior cruciate ligament balance during stair climbing was developed and used to assess the performance of one type of highly cross-linked polyethylene tibial knee insert in comparison with conventional polyethylene. The highly cross-linked inserts and one group of conventional inserts were tested after sterilization. One additional group of conventional inserts was subjected to accelerated aging before testing. The articular surfaces of the inserts were inspected visually for surface delamination, cracking, and pitting at regular intervals during the test. The aged conventional polyethylene inserts showed extensive delamination and cracking as early as 50,000 cycles. In contrast, the unaged conventional and highly cross-linked polyethylene inserts did not show any subsurface cracking or delamination at 0.5 million cycles. The appearance and location of delamination that occurred in the aged conventional inserts tested with the current model previously have been observed in vivo with posterior cruciate-sparing design knee arthroplasties with a tight posterior cruciate ligament.
Topics: Knee Prosthesis; Materials Testing; Oxidation-Reduction; Polyethylene; Polyethylenes; Prosthesis Failure; Stress, Mechanical
PubMed: 12439243
DOI: 10.1097/00003086-200211000-00015 -
Pediatrics Jul 1951
Topics: Humans; Infant, Newborn; Infant, Premature; Intubation, Gastrointestinal; Polyethylene; Polyethylenes
PubMed: 14853620
DOI: No ID Found