Clinical, surface damage and oxidative performance of poly II tibial inserts after long-term implantation

Abstract

Carbon fiber-reinforced ultra-high molecular weight polyethylene (Poly II) was clinically introduced in the 1970s, but catastrophic short-term outcomes were reported in case studies. Clinical use of Poly II persisted into the 1980s until it was eventually abandoned. To date, no studies have documented its long-term clinical and material performance. Forty Poly II tibial inserts of the Total Condylar, Insall-Burstein I, and Miller-Galante I designs were retrieved at revision surgery. Twenty-six historical unreinforced polyethylene knee retrievals of similar designs (Miller-Galante I and II, and Insall-Burstein II) served as the control group. The average in vivo durations of both retrieval groups were similar (11.1 and 11.6 years, respectively), although Poly II had a wider implantation range (3.7-32.8 years) than historical polyethylene (4.4-17.0 years). Surface damage on all the retrievals, as well as oxidation and mechanical strength when possible, were characterized. Poly II tibial inserts had long-term clinical survivability and material performance comparable to unreinforced polyethylene bearings. Poly II retrievals exhibited less surface damage at all the regions than historical components, and they were less sensitive to pitting and delamination, but more susceptible to abrasion and embedded debris. Both Poly II and historical retrievals were found to oxidize in vivo and exhibited similar mechanical strength. This study provides improved understanding of well-consolidated Poly II long-term retrievals and also motivation to revisit carbon fiber-reinforced polymeric bearings for joint replacement in the twenty-first century.