Revision Total Knee Arthroplasty Causes of failure, bone loss management and outcomes\

Abstract

The objectives of the current study were to identify the causes leading to revision knee arthroplasty, analyse implant choices and assess the short-term outcome. The current study is a retrospective on including a group of 33 patients operated between Jan 2013-Dec 2016 in a single institution. Data was collected from the Romanian National Arthroplasty Register. The cause for revision surgery was noted, as well as the type of implant used during the surgical procedure. The bony defect was classified according to the Anderson Orthopaedic Research Institute (AORI) Classification and the reconstruction method was analysed. Functional outcome was assessed using Oxford Knee Score preoperatively and at one year follow-up. Infection was the cause of failure in 18 cases, aseptic loosening in 11 cases, malposition of implants in 2 cases, instability in 1 case and periprosthetic fracture in 1 case. Revision implants were chosen based on joint stability and degree bone loss. The preferred implant was a condylar constrained knee type (20 cases), followed by a rotating hinge type (5 cases). An unconstrained implant was used in 2 cases. Six infected cases required an arthrodesis of the knee. Based on the AORI Classification, there were 10 type III defects, 14 type IIB, 8 type IIA and only one type I defect. Metal augments were preferred for reconstruction of bone defects. Bone graft was used in 8 cases. The mean Oxford Knee Score was 15 pre-op (12-20) and 38 post-op (32-45). Implant survival at final follow-up was 100%. The most common cause of failure of primary total knee arthroplasty is prosthetic joint infection. Bone defects can be addressed using metal augments or bone allograft. Postoperative functional outcome is improved irrespective of the type of implant used.