By: 19 July 2016
Highly cross-linked polyethylene for knees.  Is BioPoly® an alternative?

Dinesh Nathwani, Alister Hart, Ravi Shenoy, Herb Schwartz and Matthew Hill review the mechanical properties and advances in the development of polyethylene bearing surfaces for use in knees, discussing a new material with potentially improved mechanical and wear properties

Highly cross-linked polyethylene (HXLPE) has been and continues to be commonly used for liners in total hip arthroplasty (THA) due to its known ability to reduce wear during articulation. Its use in the tibial tray for total knee arthroplasty (TKA), however, has been much more controversial. Specifically, decreased mechanical properties and larger wear particles are concerning. A new micro-composite with hydrophilic properties, known as BioPoly®, may be able to offer an alternative material to offset some of the current concerns regarding HXLPE in total knee replacements (TKR).

History and properties of HXLPE

Before examining the use of HXLPE in the knee, it is important to understand the history and properties of the material as used for hip liners. Ultra-high molecular weight polyethylene (UHMWPE) was first introduced in the 1970s by John Charnley as a bearing material for THA. Although the material was successful, concerns eventually grew in regard to implant loosening due to osteolysis (bone loss surrounding an implant) in the 1990s. Polyethylene wear particles are the primary cause of osteolysis as they induce an autoimmune response that results in bone resorption. Osteolysis has now been shown to be one of the most common causes of revision for primary THA [1]. In response to this problem, HXLPE was developed. …

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