Results of a Modular Revision System in Total Knee Arthroplasty.

BACKGROUND Revision total knee arthroplasty (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. METHODS A query of our practice registry revealed 257 consented patients (274 knees and 278 TKA) with minimum 2-year follow-up who underwent aseptic revision TKA with a modular system (Vanguard Super Stabilized Knee; Zimmer Biomet, Warsaw, IN) between 2005 and 2013. Four patients were rerevised to a second Vanguard Super Stabilized Knee 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 2, 8 others with instability, 1 with hypersensitivity, and 1 revised elsewhere for unknown cause. Ten knees were revised for infection. Range of motion 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, 1 tibial radiolucency, 1 femoral and tibial radiolucency, and 1 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 rerevision, good knee stability, and substantial improvements in range of motion and clinical and functional outcomes.