Abstract
Background: Total knee arthroplasty (TKA) overall is a very reliable, durable procedure. Biomechanical studies have suggested superior stress distribution in metal-backed tibial trays, however, these results have not been universally observed clinically. Currently there is a paucity of information examining the survival and outcomes of all-polyethylene tibial components.
Methods: We reviewed 31,939 patients undergoing a primary TKA over a 43-year period (1970–2013). There were 28,224 (88%) metal-backed and 3,715 (12%) all-polyethylene tibial components. The metal-backed and all-polyethylene groups had comparable demographics with respect to sex distribution (57% female for both) mean age (67 vs. 71 years), and mean BMI (31.6 vs. 31.1). Mean follow-up was 7 years (maximum 40 years).
Results: The purpose of this investigation was to analyze the outcomes of all-polyethylene compared to metal-backed components in TKA and to determine (1) is there a difference in overall survival? All-polyethylene tibial components had improved survivorship (P<0.0001) and metal-backed tibias were at increased risk of revision (HR 3.41, P<0.0001). (2) Does body mass index (BMI) or age have an effect on survival of all-polyethylene compared to metal-backed tibial components? All-polyethylene tibias had improved survival (P<0.01) in all ages groups except in patients 85 years or greater, where there was no difference (P=0.16). All-polyethylene tibial components had improved survival (P<0.005) for all BMI's except in the morbidly obese (BMI ≥40) where there was no difference (P=0.20). (3) Is there an increased risk of post-operative infection? Metal-backed tibial components were found to have an increased risk of infection (HR 1.60, P=0.003). (4) Is there a difference in the rate of reoperation and post-operative complications? Metal-backed tibial components were found to have an increased risk of reoperation (HR 1.84, P<0.0001).
Conclusions: The use of all-polyethylene tibias should be considered for the majority of patients, regardless of age and BMI.
