Tobacco Exposure Is Associated With Extremely Low Polyethylene Oxidation in Total Knee Arthroplasty Components

We evaluate whether patient exposures such as tobacco use are associated with high systemic or local in vivo oxidative state and with increased in vivo polyethylene oxidation.

We performed a case-control study which evaluated clinical factors associated with high systemic or local in vivo oxidative state among patients whose implants have been identified as demonstrating either extreme or minimal oxidation by our implant retrieval laboratory. Analysis of more than 2500 tibial inserts from explanted total knee arthroplasty demonstrated a wide spectrum of polyethylene oxidation. Components from some patients exhibited extremely high oxidation rates (super-oxidizers), and components from other patients demonstrated negligible oxidation (nonoxidizers). Patients' clinical data were retrospectively investigated from a prospectively collected institutional database.

Eighteen patients met criteria as either super-oxidizers (9) or nonoxidizers (9). Average time in vivo was 6.6 (±4.4) years. Reasons for removal were aseptic loosening (10), instability (3), infection (2), component malposition (1), massive osteolysis (1), and other (1). Chi-square for categorical predictors demonstrated that nonoxidizer patients were significantly more likely to be current smokers than super-oxidizers (6 vs 0, P = .012). No other free radical-associated variables were significantly different across oxidation groups.

There was a significant association between extremely low ultra-high-molecular-weight polyethylene oxidation and current smoking.