Comparison of CT-based patient-specific templating and digital radiography templating in total knee arthroplasty

AimThe aim of the prospective study is to evaluate and compare the accuracy of digital templating and CT-based templating in preoperative planning, in determining the size of the femoral and tibial component in total knee arthroplasty.Materials and methodsA prospective study was conducted to compare the accuracy in predicting the size of the prosthetic components in total knee replacement in 81 patients. Preoperatively, all the patients underwent the same standard protocol including digital radiographs with calibration and a CT scan. A dedicated IMPAX digital software was used to template the radiographs. The CT-based planning was performed on 3D reconstruction of CT scans as per standardized protocol for patient-specific instrumentation.ResultThe planning of digital radiography indicates the correct size in 71% of the cases for the femoral component and 47% for the tibial component. CT-based planning reached an accuracy of 93% for the femur and 54% for the tibia in predicting the exact size. The accuracy reaches 100% for both components if considered the maximum error of one size in CT-based planning. There were no surgical complications in any of the cases.DiscussionThe improvement in the ability to predict the size of the prosthetic components obtained by the CT images is statistically significant compared to that obtained by the radiographic study to predict the size of the tibial and femoral component. CT can indicate the number of size within the maximum error of measurement of one size in 100% of cases and this can be helpful to the surgeon and the organization in terms of trays to be sterilized, OR turnover, and cost savings. It appears that CT-based patient-specific templating is relatively easy to use, less invasive, saves time, and improves the accuracy in the positioning of the prosthetic components.