Double Trabecular Tantalum Cones as an Alternative to Additive Technologies for Revision Knee Arthroplasty (A Case Series)

Relevance. To compensate the extensive (AORI type III) bone defects, metal cones/ sleeves or massive allografts are used. In the absence of metaepiphyses, structural allografts or megaprostheses are usually used for tumor lesions of the bones. The aim of the study was to show the possibility of replacing extensive type III defects of the femur and tibia, covering the metaphysical and diaphyseal zones, with double tantalum cones.Materials and Methods. The study included 13 patients undergone revision knee arthroplasty in 2015–2019. During the surgery, the primary fixation of the femoral or tibial component was achieved by the tight fit diaphyseal cone placement. The additional fixation is сarried out by cementing of the metaphyseal cone to the diaphyseal cone and the further osseointegration with the remaining bone of the metadiaphyseal zone. Fixation of the endoprosthesis component to the cones and to the bone is achived by use of the bone cement.Results. The short-term outcomes of this technique in revision knee arthroplasty were evaluated in all patients. The results were evaluated as good if the primary stable fixation and the correct endoprosthesis components placement were achieved, the limb support ability and the knee function were restored, and there were no complications in the immediate postoperative period. In a year, one patient developed a relapse of infection in the operated knee. The endoprosthesis was removed and followed by knee arthrodesis after sanitation of the infection focus. Functional and radiological results one year after surgery were studied in 4 patients. The average functional scores were: by KSS 81 (good) and by WOMAC — 25 points (also good). On the control radiographs, the position of the components remained correct and stable with osseointegration of the cones in the metaphyseal and diaphyseal areas of the femur and tibia. In the remaining 8 patients, the time after surgery was less than a year. Their follow-up yet continued.Conclusion. Thus, the tantalum cones technique is a reliable way to reconstruct extended metadiaphyseal defects in revision knee arthroplasty in the short-term prospect. The method can be considered as an alternative to megaprostheses, structural allografts, and individually made cones. But the long-term results of its application are still requiri ng further study.