The Effect of Polyethylene Liner Thickness on Patient Outcomes and Failure After Primary Total Knee Arthroplasty

Background: The effect of using thicker liners in primary total knee arthroplasty (TKA) on functional outcomes and aseptic failure rates remains largely unknown. As such, we devised a multicenter study to assess both the clinical outcomes and survivorship of thick vs thin liners after primary TKA. Methods: A search of our institutional databases was performed for patients having undergone bilateral (simultaneous or staged) primary TKA with similar preoperative and surgical characteristics between both sides. Two cohorts were created: thick liners and thin liners. Outcomes collected were as follows: change in Knee Society Score (Delta KSS), change in range of motion, and aseptic revision. Ad hoc power analysis was performed for Delta KSS (alpha = 0.05; power = 80%). Differences between cohorts were assessed. Results: About 195 TKAs were identified for each cohort. Delta KSS and change in range of motion in the thin vs thick cohorts were similar: 51.4 vs 51.6 (P .86) and 11.1 degrees vs 10.0 degrees (P=.66), respectively. No difference in aseptic revision rates were observed between thin and thick cohorts: all cause (4.1%, 3.1%; P = .59), aseptic loosening (0.5%, 0.5%; P=1.0), instability (0.5%, 0.5%; P=1.0), all-cause revision for stiffness (3.1%, 2.1%; P=.52), manipulation under anesthesia (2.1%, 2.1%; P= 1.0), and liner exchange (0.5%, 0%; P=.32). Conclusion: The results of this study suggest that both rates of revision surgery and clinical outcomes are similar for TKAs performed with thick and thin liners. Preoperative factors are likely to play an important role in liner thickness selection, and emphasis should be placed on ensuring sound surgical technique. (C) 2020 Elsevier Inc. All rights reserved.