Tantalum Cones in Revision Total Knee Arthroplasty. A Promising Short-Term Result With 29 Cones in 21 Patients

Twenty-nine porous tantalum metaphyseal cones were implanted in 21 patients (14 women and 7 men) during revision TKA. The average age at the time of the procedure was 73.3 years. Sixteen revisions were considered aseptic and 5 were reimplantations after sepsis. Eight patients had stemmed revision implants and thirteen primary designs. According to the Anderson Orthopaedic Research Institute bone defect classification, femoral defects were rated as F3 in 14 knees and F2B in 3 knees. Tibial defects were rated as T2A in 3 cases, T2B in 3 cases and T3 in 5 cases. A femoral cone was inserted in 10 patients, a double cone (femur and tibia) in 8, and a single tibial cone in 3. A rotating hinge knee prosthesis (RHK, Zimmer) was inserted in 10 patients and a constrained condylar prosthesis (LCCK, Zimmer) in 11 patients. The diaphysis was cemented in 9 cases and, in 11 cases, just the metaphysis. At an average follow up of 36 months only one reconstruction was removed due to persistent infection. All metaphyseal cones showed evidence of stable osseointegration. According to the Knee Society Score the results were rated as excellent in 12 cases, good in 5 cases, fair in 3 and poor in 1 case. In the short term, porous tantalum metaphyseal cones provided structural support for large femoral and tibial defects. They also provided the environment for bone graft osseointegration, repair of femoral fractures and effective interdigitation of cement mantle into the trabecular metal cone.