Is Cement Mantle Thickness a Primary Cause of Aseptic Tibial Loosening Following Primary Total Knee Arthroplasty?

Background: Aseptic tibial loosening following primary total knee replacement is one of the leading causes of long-term failure. Cement mantle thickness has been implicated as a source of aseptic tibial loosening. Therefore, the following study was designed to deter-mine (1) what is the cement mantle thickness in patients that develop aseptic tibial loos-ening, and (2) is there a difference in cement mantle thickness based on the interface of failure?Method: This retrospective cohort included 216 patients revised for aseptic tibial loosen-ing. Patient demographics, operative data, and clinical outcomes were recorded. A preop-erative radiographic assessment was performed to determine the interface of failure and the thickness of the cement mantle using the Knee Society Radiographic Evaluation System zones.Results: The average patient age was 65 years and body mass index was 33.7 kg/m2. 203 patients demonstrated radiographic failure at the implant-cement interface and 13 patients demonstrated failure at the cement-bone interface. The average cement mantle thickness of each radiographic zone for the entire cohort on the AP and lateral views was 4.4 and 4.5 mm, respectively. The average cement mantle thickness of patients that developed failure at the implant-cement interface was significantly greater than patients that failed at the cement-bone interface in each radiographic zone (p < 0.001). Conclusions: Patients that develop implant loosening at the cement-bone interface were noted to have a significantly decreased cement mantle compared to patients that failed at the implant-cement interface. Methods for decreasing tibial implant loosening should likely focus on improving the fixation at the implant-cement interface.(c) 2022 Elsevier B.V. All rights reserved.