Results of a Modular Revision System in Total Knee Arthroplasty

Abstract Background Revision TKA poses unique challenges compared with primary TKA such as bone loss, deformity and ligament instability. Modular component options allow flexibility to deal with these complexities. The purpose of this study was to evaluate midterm outcomes for revision TKA using a modular revision knee system with complete interchangeability and multiple options for augmentation, offset, constraint, and stem extensions. Materials and Methods A query of our practice registry revealed 257 consented patients (274 knees, 278 TKA) with minimum 2-year follow-up who underwent aseptic revision TKA with a modular system (Vanguard SSK, Zimmer Biomet, Warsaw, Indiana) between 2005 and 2013. Four patients were re-revised to a second Vanguard SSK within the study period. Mean age was 68 years, and mean number of previous surgeries was 2 (1-14). Results At mean follow-up of 6.0 years (range, 2-11 years) there have been 25 aseptic revisions involving one or more components (9.0%): 15 aseptic loosening with concomitant instability in two, 8 others with instability, one hypersensitivity, and one revised elsewhere for unknown cause. Ten knees were revised for infection. ROM improved from 100° preoperatively to 105° most recently. Knee Society clinical scores improved from 45 to 79, and function scores from 46 to 56. Radiographic evaluation revealed satisfactory position, fixation and alignment in 97% and abnormal findings in 7 knees: 4 limited to the patella, one tibial radiolucency, one femoral and tibial radiolucency, and one tibial subsidence. Conclusion The results of this modular TKA revision system at 6 years mean follow-up are promising for use in complex scenarios, with a low frequency of aseptic re-revision, good knee stability, and substantial improvements in ROM and clinical and functional outcomes.