Use of porous tantalum metaphyseal cones for severe tibial bone loss during revision total knee replacement.

BACKGROUND: The best treatment method for large tibial bone defects during revision knee replacement has not been established. The purpose of this study was to determine the initial results obtained with a unique reconstructive implant, the porous tantalum metaphyseal cone, designed as an alternative treatment for severe tibial bone loss following total knee arthroplasty.
METHODS: Porous tantalum metaphyseal cones were implanted during fifteen revision total knee replacements in eight women and seven men who had an average age of 68.1 years at the time of the procedure. The patients had had an average of 3.5 prior total knee replacements. According to the Anderson Orthopaedic Research Institute bone defect classification, eight knees had a Type-3 defect and seven knees had a Type-2B bone defect. All patients were followed clinically and radiographically.
RESULTS: The patients were followed for an average of thirty-four months (range, twenty-four to forty-seven months). Overall, the average Knee Society clinical scores improved from 52 points preoperatively to 85 points at the time of the final follow-up. At the final follow-up evaluation, all fifteen porous metaphyseal cones showed evidence of osseointegration with reactive osseous trabeculation at points of contact with the tibia. There was no evidence of loosening or migration of any of these tibial reconstructions at the time of final follow-up.
CONCLUSIONS: At the time of short-term follow-up, the porous tantalum metaphyseal tibial cones effectively provided structural support for the tibial implants in this series. The potential for long-term biologic fixation may provide durability for these tibial reconstructions. Long-term follow-up and comparison with alternative reconstructive techniques will be required to evaluate the true effectiveness of this treatment approach.