Dataset Information

Behavior of Hylamer polyethylene in hip arthroplasty: comparison of two gamma sterilization techniques.

ABSTRACT: Hylamer polyethylene was introduced in the 1990s as an alternative to conventional polyethylene. Its chemical and physical properties, and especially its high crystallinity, were claimed to improve resistance to wear. Initially Hylamer devices were sterilized by gamma radiation in air, then the technique was changed and gamma radiation was performed in the absence of oxygen. Clinical experience has shown the early loosening of some devices made from Hylamer. The aim of this study was to ascertain whether early wear and consequent osteolysis was linked to the sterilization method. We retrospectively compared 31 patients with hip prostheses with Hylamer liners sterilized by gamma radiation in air (group 1) with 30 patients with the same prosthesis, but sterilized in the absence of oxygen (group 2). The groups were similar for sex, age, disease, head diameter and material. Mean follow-up was 84 months and no clinical signs of failure were present. Radiographic measurement revealed that wear of group 1 was significantly greater than that of group 2 (0.23 mm/year vs 0.09 mm/year, p=0.001). Periacetabular and femoral osteolysis in group 1 was significantly greater than group 2. In conclusion, the method of sterilization might have influenced the outcome of Hylamer polyethylene liners.

SUBMITTER: Stea S

PROVIDER: S-EPMC2254662 | biostudies-other | 2006 Feb

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:In the 1990s, oxidation was found to occur in ultra-high molecular weight polyethylene total joint replacement components following gamma irradiation and prolonged shelf aging in air. Orthopaedic manufacturers developed barrier packaging to reduce oxidation during and after radiation sterilization. The present study explores the hypothesis that polyethylene components sterilized in a low-oxygen environment undergo similar in vivo oxidative mechanisms as inserts sterilized in air. In addition, the potential influence of the different sterilization processes on the wear performance of the polyethylene components was examined.An analysis of oxidation, wear, and surface damage was performed for forty-eight acetabular liners and 123 tibial inserts. The mean implantation time was 12.3+/-3.7 years for thirty-one acetabular liners that had been gamma sterilized in air and 4.0+/-2.5 years for the seventeen acetabular liners that had been gamma sterilized in inert gas. The mean implantation time was 11.0+/-3.2 years for the twenty-six tibial inserts that had been sterilized in air and 2.8+/-2.2 years for the ninety-seven tibial inserts that had been gamma sterilized in inert gas. Oxidation and hydroperoxide levels were characterized in loaded and unloaded regions of the inserts.Measurable oxidation and oxidation potential were observed in all cohorts. The oxidation and hydroperoxide levels were regional. Surfaces with access to body fluids were more heavily oxidized than protected bearing surfaces were. This variation appeared to be greater in historical (gamma-in-air-sterilized) components. Regarding wear performance, historical and conventional acetabular liners showed similar wear penetration rates, whereas a low incidence of delamination was confirmed for the conventional tibial inserts in the first decade of implantation.The present study explores the impact of industry-wide changes in sterilization practices for polyethylene. We found lower oxidation and oxidation potential in the conventional acetabular liners and tibial inserts that had been gamma sterilized in inert gas as compared with the historical components that had been gamma sterilized in air. However, we also found strong evidence that conventional components undergo mechanisms of in vivo oxidation similar to those observed following gamma irradiation in air. In addition, gamma sterilization in inert gas did not provide polyethylene with a significant improvement in terms of wear resistance as compared with gamma sterilization in air, except for a lower incidence of delamination in the first decade of implantation for tibial inserts.

Project description:The behavior of many wild animals remains a mystery, as it is difficult to quantify behavior of species that cannot be easily followed throughout their daily or seasonal movements. Accelerometers can solve some of these mysteries, as they collect activity data at a high temporal resolution (<1 s), can be relatively small (<1 g) so they minimally disrupt behavior, and are increasingly capable of recording data for long periods. Nonetheless, there is a need for increased validation of methods to classify animal behavior from accelerometers to promote widespread adoption of this technology in ecology. We assessed the accuracy of six different behavioral assignment methods for two species of seabird, thick-billed murres (Uria lomvia) and black-legged kittiwakes (Rissa tridactyla). We identified three behaviors using tri-axial accelerometers: standing, swimming, and flying, after classifying diving using a pressure sensor for murres. We evaluated six classification methods relative to independent classifications from concurrent GPS tracking data. We used four variables for classification: depth, wing beat frequency, pitch, and dynamic acceleration. Average accuracy for all methods was >98% for murres, and 89% and 93% for kittiwakes during incubation and chick rearing, respectively. Variable selection showed that classification accuracy did not improve with more than two (kittiwakes) or three (murres) variables. We conclude that simple methods of behavioral classification can be as accurate for classifying basic behaviors as more complex approaches, and that identifying suitable accelerometer metrics is more important than using a particular classification method when the objective is to develop a daily activity or energy budget. Highly accurate daily activity budgets can be generated from accelerometer data using multiple methods and a small number of accelerometer metrics; therefore, identifying a suitable behavioral classification method should not be a barrier to using accelerometers in studies of seabird behavior and ecology.

Dataset Information

Behavior of Hylamer polyethylene in hip arthroplasty: comparison of two gamma sterilization techniques.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets