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.