Excellent two-year survivorship of 3D-printed metaphyseal cones in revision total knee arthroplasty: A reliable and safe reamer-based system

Aims Metaphyseal fixation during revision total knee arthroplasty (TKA) is important, but potentially difficult when using historical designs of cone. Material and manufacturing innovations have improved the size and shape of the cones which are available, and simplified the required bone preparation. In a large series, we assessed the implant survivorship, radiological results, and clinical outcomes of new porous 3D-printed titanium metaphyseal cones featuring a reamer-based system. Methods We reviewed 142 revision TKAs in 139 patients using 202 cones (134 tibial, 68 femoral) which were undertaken between 2015 and 2016. A total of 60 involved tibial and femoral cones. Most cones (149 of 202; 74%) were used for Type 2B or 3 bone loss. The mean age of the patients was 66 years (44 to 88), and 76 (55 %) were female. The mean body mass index (BMI) was 34 kg/m2 (18 to 60). The patients had a mean of 2.4 (1 to 8) previous operations on the knee, and 68 (48%) had a history of prosthetic infection. The mean follow-up was 2.4 years (2 to 3.6). Results Survivorship free of cone revision for aseptic loosening was 10 0% and survivorship free of any cone revision was 98%. Survivorships free of any revisio n and any reoperation were 90% and 83%, respectively. Five cones were revised: Three for infection, one for periprosthetic fracture, and one for aseptic tibial loosening. Radiologically, three unrevised femoral cones appeared loose in the presence of hinged implants, while the remaining cones appeared stable. All cases of cone loosening oc curred in patients with Type 2B or 3 defects. The mean Knee Society score (KSS) improve d significantly from 50 (0 to 94) preoperatively to 87 (72 to 94) (p < 0.001). Three in traoperative fractures with cone impaction (two femoral, one tibial) healed uneventfully. Conclusion Novel 3D-printed titanium cones, with a reamer-based system, yielded excellent early survivorship and few complications in patients with severe bone loss undergoing difficult revision TKA. The diversity of cone options, relative ease of preparation, and outcomes rivalling those of previous designs of cone support their continued use.