Poorer survival after a primary implant during revision total knee arthroplasty

Revision total knee arthroplasty (rTKA) is a complex procedure. Depending on the degree of ligament and bone damage, either primary or revision implants are used. The purpose of this study was to compare survival rates of primary implants with revision implants when used during rTKA. A retrospective comparative study was conducted between 1998 and 2009 during which 69 rTKAs were performed on 65 patients. Most common indications for revision were infection (30 %), aseptic loosening (25 %) and wear/osteolysis (25 %). During rTKA, a primary implant was used in nine knees and a revision implant in 60. Survival of primary implants was 100 % at one year, 73 % [95 % confidence interval (CI) 41-100] at two years and 44 % (95 % CI 7-81) at five years. Survival of revision implants was 95 % (95 % CI 89-100) at one year, 92 % (95 % CI 84-99) at two years and 92 % (95 % CI 84-99) at five years. Primary implants had a significantly worse survival rate than revision implants when implanted during rTKA [P = 0.039 (hazard ratio = 4.56, 95 % CI 1.08-19.27)]. Based on these results, it has to be considered whether primary implants are even an option during rTKA.