Early Survivorship of Newly Designed Highly Porous Metaphyseal Tibial Cones in Revision Total Knee Arthroplasty

Background: Metaphyseal cones provide durable fixation in revision total knee arthroplasty (TKA). However, there is a paucity of data on the outcomes of a new porous cone design. As such, the goal of this study was to analyze the early survivorship in patients undergoing revision TKA with this cone. Methods: We retrospectively reviewed 163 revision TKAs with a newly designed porous tibial cone from 2016 to 2018. Mean age was 67 years, and mean body mass index was 33 kg/m2. Minimum follow-up duration was 2 years. Most patients were revised for aseptic loosening (46%), 2-stage periprosthetic joint infection (PJI) reimplantation (28%), or instability (15%). Most were varus-valgus constrained (65%) or hinged (32%) constructs. The majority had hybrid tibial stem fixation (74%). A multivariate Cox regression analysis was used to identify risk factors for reoperation. Results: Survivorship free from re-revision for aseptic loosening, any nonmodular revision, and any reoperation was 100%, 96%, and 86% at 2 years, respectively. No patients were revised for aseptic loosening. Six (4%) tibial cones were removed for PJI, one of which was loose. There were 23 reoperations (14%), most commonly for PJI (10%). Multivariate analysis identified PJI reimplantation (hazard ratios [HR] = 4.2, P = .002), males (HR = 2.9, P = .02), and hinged constructs (HR = 2.7, P = .02) as significant risk factors for reoperation. Conclusions: In a complex revision TKA cohort with a new highly porous tibial cone, in which most patients received hybrid stem fixation and nonlinked and linked constraint, there was 100% survival free from re-revision for aseptic loosening at 2 years. Longer term follow-up is required.