Stacked Cones for the Treatment of Massive Bone Loss in Revision Total Knee Arthroplasty: 50% Reoperation Rate at Five Years.

Abstract

Metaphyseal cones can be used to address bone loss and/or obtain reliable biologic fixation in revision total knee arthroplasties (TKAs). Sometimes, larger bone defects mandate using more than one cone on either the femoral or tibial side. This study aimed to evaluate implant survivorship, radiographic results, and clinical outcomes of revision TKAs with multiple stacked cones. We identified 50 revision TKAs using stacked cones performed at a single academic institution from 2011 to 2021. Stacked cones were used in the tibia in 26 patients (52%), femur in 22 patients (44%), and both in two patients (4%). The mean age was 69 years, the mean body mass index was 33, and 74% were men. Kaplan-Meier survivorship curves were calculated, radiographs were reviewed, and clinical outcomes were evaluated with Knee Society Function Score. The mean follow-up was 5 years (range, 17 days to 10 years). The 5-year survivorship free of rerevision for aseptic loosening of the stacked cone constructs was 93%, and free of any stacked cone rerevision was 75%. There were nine stacked cone constructs (six femoral and three tibial) rerevised, with periprosthetic joint infection (PJI; n = 7; 3 with prior PJI) and aseptic loosening (n = 2) being the indications for rerevision. The 5-year survivorship free of any rerevision and any reoperation was 58 and 50%, respectively. There were 17 rerevisions, with aseptic loosening (n = 8) and PJI (n = 8) being the most common reasons. There were two nonrerevised stacked cone constructs that had signs of radiographic loosening. The mean Knee Society Score was 54. Stacked cones demonstrated modest survivorship at a mean 5-year follow-up with a low rate of aseptic loosening. However, 50% of these cases required a reoperation, highlighting this complex cohort and selection bias to those receiving stacked cones.