Article

Highly crosslinked vs conventional polyethylene particles--an in vitro comparison of biologic activities.

Department of Orthopedics and Rehabilitation, School of Medicine, and Public Health, University of Wisconsin, Madison, Wisconsin 53792, USA.
The Journal of arthroplasty (impact factor: 1.79). 05/2008; 23(5):721-31. DOI:10.1016/j.arth.2007.05.043 pp.721-31
Source: PubMed

ABSTRACT Highly cross-linked polyethylenes (HXPEs) have been introduced to reduce wear after hip arthroplasty. The improved wear characteristics of HXPEs are well documented, but the relative biologic activity of HXPE and conventional polyethylene (CPE) particles remains unclear. Longevity (Zimmer, Warsaw, Ind; HXPE) and GUR 1050 (Zimmer; CPE) particles were isolated and characterized from a hip simulator and their in vitro inflammatory responses (tissue necrosis factor *, interleukin 1*, and vascular endothelial growth factor levels) were compared using macrophages. The average diameter of Longevity particles (0.111 microm) was smaller than CPE particles (0.196 microm), and both were predominantly round (granular appearance). The inflammatory response to HXPE and CPE was concentration-dependent. No statistically significant differences were noted at low (0.1 surface area ratio [SAR]) and intermediate (0.75 SAR) doses. At the highest dose tested (2.5 SAR), HXPE was significantly more inflammatory than CPE based on relative tissue necrosis factor alpha and vascular endothelial growth factor secretion levels. Further study is needed to determine if similar findings would be noted in vivo over a broad concentration range.

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    Article: Characteristics of highly cross-linked polyethylene wear debris in vivo.
    Ryan M Baxter, Daniel W Macdonald, Steven M Kurtz, Marla J Steinbeck
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    ABSTRACT: Despite the widespread implementation of highly cross-linked polyethylene (HXLPE) liners to reduce the clinical incidence of osteolysis, it is not known if the improved wear resistance will outweigh the inflammatory potential of HXLPE wear debris generated in vivo. Thus, we asked: What are the differences in size, shape, number, and biological activity of polyethylene wear particles obtained from primary total hip arthroplasty revision surgery of conventional polyethylene (CPE) versus remelted or annealed HXLPE liners? Pseudocapsular tissue samples were collected from revision surgery of CPE and HXLPE (annealed and remelted) liners, and digested using nitric acid. The isolated polyethylene wear particles were evaluated using scanning electron microscopy. Tissues from both HXLPE cohorts contained an increased percentage of submicron particles compared to the CPE cohort. However, the total number of particles was lower for both HXLPE cohorts, as a result there was no significant difference in the volume fraction distribution and specific biological activity (SBA; the relative biological activity per unit volume) between cohorts. In contrast, based on the decreased size and number of HXLPE wear debris there was a significant decrease in total particle volume (mm(3) /g of tissue). Accordingly, when the SBA was normalized by total particle volume (mm(3) /gm tissue) or by component wear volume rate (mm(3) /year), functional biological activity of the HXLPE wear debris was significantly decreased compared to the CPE cohort. Indications for this study are that the osteolytic potential of wear debris generated by HXLPE liners in vivo is significantly reduced by improvements in polyethylene wear resistance. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 02/2013; · 2.15 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

0.1 surface area ratio [SAR]
 
average diameter
 
broad concentration range
 
conventional polyethylene
 
CPE particles
 
cross-linked polyethylenes
 
highest dose
 
hip simulator
 
HXPEs
 
intermediate
 
Longevity particles
 
relative biologic activity
 
relative tissue necrosis factor alpha
 
similar findings
 
statistically significant differences
 
tissue necrosis factor
 
vascular endothelial growth factor levels
 
vascular endothelial growth factor secretion levels
 
vitro inflammatory responses
 
Warsaw
 

Richard Lynn Illgen