Carbon fiber-reinforced UHMWPE composites

In the 1970s, carbon fiber-reinforced (CFR) UHMWPE composites were considered for orthopedic implants and were even commercially introduced (Poly 11, Zimmer, Inc., Warsaw, Indiana, USA). However, catastrophic short-term clinical failures [2, 3] eventually led to the abandonment of Poly 11 and the perception for decades, among surgeons and researchers alike, that UHMWPE composite materials may not be appropriate for orthopedic bearing applications. Today, with the interest in UHMWPE development that was stimulated by radiation and thermal processing techniques, as well as the growing use of UHMWPE composites in nonmedical arenas, there is renewed curiosity about these materials for biomedical applications. 

One carbon-UHMWPE composite, commonly known as Poly II (Zimmer, Inc., Warsaw, Indiana, USA), was developed commercially and used clinically. The CFR-UHMWPE was reinforced by chopped, randomly oriented carbon fibers in a direct compression molded UHMWPE matrix [4]. The carbon fiber reinforcement was initially considered to be responsible for improved wear behavior relative to UHMWPE during initial experimental testing conducted by the manufacturer [5]. However, further studies ultimately revealed that such performance came at the expense of the ductility, decreased crack resistance, and the fiber-matrix interface of the composite [6]. Subsequent wear studies also showed evidence of fiber disruption at the surface and abrasive wear of the metallic counterface [7]. Furthermore, occasional difficulties in the manufacture of the composite material resulted in incomplete consolidation of the powder and carbon fibers in certain implants [8]. Thus, after its clinical introduction, Poly II was found to exhibit wear, fracture, and extensive delamination [2, 3,9], and, as a result, the material was eventually withdrawn [ 10]. 

A wear study by McKellop et al. indicated that Poly n exhibited a 10 times greater wear rate than UHMWPE against a variety of common counterfaces, such as 316 stainless steel and CoCr alloy [19]. Because the major mechanism of wear in carbon fiber-reinforced polyethylene is abrasive wear that induces the drawing out of fibers from bearing surfaces [20], the interface strength is of critical importance in the overall performance of Poly II and similar composites. 

Xiong D. Friction and wear properties of UHMWPE composites reinforced with carbon fiber. Mater I tt 2005 59 175-9. 

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