Patient-specific computed tomography based instrumentation in total knee arthroplasty: a prospective randomized controlled study

The aim of this study was to compare radiological results of total knee arthroplasties (TKAs) performed with patient-specific computed tomography (CT)-based instrumentation and conventional technique. The main study hypothesis was that CT-based patient-specific instrumentation (PSI) increases the accuracy of TKA. A prospective, randomized controlled trial was carried out between January and December 2011. A group of 112 patients who met the inclusion and exclusion criteria were enrolled in this study and randomly assigned to an experimental or control group. The experimental group comprised 52 patients operated on with the aid of the Signature (TM) CT-based implant positioning system. The control group consisted of 60 patients operated on using conventional instrumentation. The radiographic evaluation of implant positioning and overall coronal alignment was performed 12 months after the surgery by using standing anteroposterior radiographs of the entire lower limb and standard lateral radiographs. Of the 112 patients initially enrolled for the study, 95 were included in the subsequent analyses. There were no statistically significant differences between groups in respect to coronal and sagittal component positioning and overall coronal alignment, except for frontal tibial component positioning. For this parameter, better results were obtained in the control group, with borderline statistical significance. Our study did not reveal superiority of the CT-based PSI system over conventional instrumentation. Further high-quality investigations of patient-specific systems are absolutely indispensable to assess their utility for TKA. In our opinion, the surgeon applying PSI technology is required to have advanced knowledge and considerable experience with the conventional method.