Utilizing 3d-printed patient-specific porous titanium cones in complex primary and revision total knee arthroplasty.

Abstract

Introduction: Effective management of bone defects is crucial in revision total knee arthroplasty (rTKA) to ensure implant stability in low-density bone environments, especially following prosthesis removal. While various reinforcement techniques exist, such as allografts, augments, metal cones, sleeves, or combinations thereof, metal cones are increasingly favored for their ability to reconstruct significant bone defects. A prominent challenge with off-the-shelf (OTS) cones is their unsuitability for Asian and specifically Iranian anatomies due to mismatched sizes and smaller medullary canals. This study explores the application of customized 3D-printed porous titanium cones, tailored to individual patient anatomy, for bone defect reconstruction in complex primary or revision total knee arthroplasty (TKA).

Materials and methods: Utilizing CT scans for 3D preoperative planning, porous cones were individually designed to fit each patient's anatomy. A novel aspect of these cones is their dual functionality: promoting bone ingrowth while preventing cement infiltration. The cones were fabricated using selective laser melting with medical-grade Ti6Al4V alloy. To aid in surgical preparation, single-use polyamide trials were also 3D-printed.

Results: A total of nineteen cones/half cones (four diaphyseal, twelve metaphyseal, and three meta-diaphyseal) for femoral and tibial applications were successfully designed and implanted across ten cases. There was a perfect alignment between preoperative planning and intraoperative outcomes, with precise defect reconstruction achieved in all cases. Early follow-ups indicated no loosening or implant migration.

Conclusions: Customized patient-specific porous cones offer not only the long-term benefits of OTS options, such as osseointegration and biological fixation but also accurately address a wide range of complex metaphyseal and diaphyseal defects. This approach preserves residual bone stock and streamlines the surgical process, presenting a promising advancement in bone defect management in rTKA.