Management of bone loss: augments, cones, offset stems

Abstract

Trabecular metal augmentation has added new treatment options for severe proximal tibial bone defects in revision knee arthroplasty. Porous tantalum tibial cones provide mechanical support for the tibial component and have the potential for long-term biologic fixation. These cones facilitate restoration of the proximal tibia metaphysis in Type 2 and 3 defects. Ten tantalum tibial cones were press-fit into the prepared cavitary defect of a series of revision knee arthroplasties. Voids between the cone and host bone were filled with morselized grafting material. The core tibial component was cemented into the implanted tibial cone; fixation was enhanced with stem extensions, which were press-fit in four knees and cemented in six knees. Extensions ranged from 75-200 mm with length dependent upon the residual bone quality. Offset stems were used in 3 tibias. At follow-up (average 10 months), radiographic evaluation revealed no evidence of loosening or change in position. Strength, range of motion, and stability were comparable to previously reported series of revision arthroplasties. Trabecular metal cones can help reconstruct large cavitary defects and, along with stem extensions and offset stems, may eliminate the need for extensive bone grafting or structural allograft in revision knee arthroplasty.

Level of evidence: Therapeutic study, level V (expert opinion). See the Guidelines for Authors for a complete description of levels of evidence.