Three-dimensional analysis of accuracy of component positioning in total knee arthroplasty with patient specific and conventional instruments: A randomized controlled trial

Component malalignment remains a major concern in total knee arthroplasty (TKA). Patient-specific guides (PSG) were developed to increase accuracy of bone resections and component placement, but available evidence is contradictory. We assessed the accuracy of 3D component placement in TKA with PSG compared to conventional surgery using virtual 3D bone models. Fifty patients were randomly assigned to the PSG or conventional instrumentation group, 44 were finally analyzed. Preoperatively, MRI and CT scans were converted into virtual 3D models and a surgical plan was developed. Surgery was performed and changes in component sizing were recorded. Postoperative CT images were converted to 3D models and aligned to the planned, preoperative models and implant orientation. Differences between planned and postoperative implant orientations were calculated in 3D. PSG allowed significantly more accurate varus/valgus placement for the femoral component (PSG: 0.14±1.47; control: 1.40±1.99; p