Clinical trade‐offs in cross‐linked ultrahigh‐molecular‐weight polyethylene used in total joint arthroplasty

Abstract

Highly cross-linked formulations of ultrahigh-molecular-weight polyethylene (XLPE) offer exceptional wear resistance for total joint arthroplasty but are offset with a reduction in postyield and fatigue fracture properties in comparison to conventional ultrahigh-molecular-weight polyethylene (UHMWPE). Oxidation resistance is also an important property for the longevity of total joint replacements (TJRs) as formulations of UHMWPE or XLPE utilizing radiation methods are susceptible to free radical generation and subsequent embrittlement. The balance of oxidation, wear, and fracture properties is an enduring concern for orthopedic polymers used as the bearing surface in total joint arthroplasty. Optimization of material properties is further challenged in designs that make use of locking mechanisms, notches, or other stress concentrations that can render the polymer susceptible to fracture due to elevated local stresses. Clinical complications involving impingements, dislocations, or other biomechanical overloads can exacerbate stresses and negate benefits of improved wear resistance provided by XLPE. This work examines trade-offs that factor into the use of XLPE in TJR implants.

Wear of highly crosslinked polyethylene acetabular components

“…When used in primary THA, XLPE has a lower rate of revision for any reason than conventional PE ( AOANJRR 2013 ). Different companies continue to use different manufacturing methods for each XLPE product, aiming to balance resistance to wear, oxidation, and fatigue fracture ( Pruitt et al 2013 ). Ideally, as with all new prosthetic components, new XLPEs should be rigorously tested in clinical trials before being released for general use because of potential variation in manufacturing methods, which may lead to possible failure ( Rohrl et al 2005 , Malchau et al 2011 ).…”

Biomechanical Effect of Various Tibial Bearing Materials in Uni-Compartmental Knee Arthroplasty Using Finite Element Analysis

“…Developments during the last decades have presented significant changes in manufacturing and sterilization methods, as well as material technologies, enhancing the mechanical properties, oxidative stability, and wear of UHMWPE [13,14]. However, such an apparent trade-off between each of these factors with increasing cross-linkage is associated with a decrease in fatigue resistance [13,14]. There have been several investigations of substitute materials for UHMWPE, including poly-ether-ether-ketone (PEEK) and carbon-fiber-reinforced PEEK (CFR-PEEK).…”

Wear of Biopolymers under Reciprocating Sliding Conditions against Different Counterfaces

“…It has been reported that the wear rate of PE increases due to the presence of scratches on the counterface and the presence of third‐body particles such as bone chips, bone cement, metal beads, broken wires, particles of bone, and other wear debris . It has been found that crosslinking with irradiation has improved the wear resistance of conventional UHMWPE, with a concomitant reduction in mechanical properties such as ultimate tensile strength, ductility, fracture toughness, and fatigue crack propagation resistance . Therefore, a number of researchers have raised concerns regarding the long‐term durability of XLPE .…”

“…It has been found that crosslinking with irradiation has improved the wear resistance of conventional UHMWPE, with a concomitant reduction in mechanical properties such as ultimate tensile strength, ductility, fracture toughness, and fatigue crack propagation resistance . Therefore, a number of researchers have raised concerns regarding the long‐term durability of XLPE . In vitro and in vivo studies of hip arthroplasty have indicated that crosslinking can reduce PE wear by up to 80%–90% .…”