3D-Printed Porous Titanium Augments for Reconstruction of Massive Bone Defect in Complex Revision Total Knee Arthroplasty: Implant Design and Surgical Technique

Reconstruction of severe bone defects in revision total knee arthroplasty (TKA) remains a challenge for orthopaedists. The progression of medical imaging and additive manufacturing technology has enabled the rapid manufacture of custom-made implants, and 3D-printed augments with interconnected pore structures have become an alternative approach for the reconstruction of bone defects in revision TKA, especially in patients with complex bone defects. The size and location of the bone defect were determined by thin-layer computed tomography (CT; layer thickness is 1 mm) after reduction of artifacts. The 3D reconstruction models of the host bone were obtained based on thin-layer CT imaging. The custom-made augmentation was designed according to the 3D reconstruction bone model. The augmentation had an interconnected porous structure on the bone-implant interface to achieve biological fixation. After the design was complete, the 3D model of augment was exported in STL format, and augments were fabricated with Ti6Al4V powder using electron beam melting. Thin-layer CT and 3D reconstruction bone models are accurate methods for evaluating periprosthetic bone loss after artifact reduction. The 3D-printed augments perfectly match the bone defects during surgery. 3D-printed augmentation is an effective approach for the reconstruction of bone defects in revision TKA. Thus, surgeons and engineers should carefully evaluate the bone defect during augment design to avoid a mismatch between the augment and host bone.