Abstract
The ability to predict accurate sizing of the implant components for total knee arthroplasty
surgery can have several benefits in the operating room, in terms of simplifying the
workflow and reducing the number of required instrument trays. Planning on a three-dimensional
(3D) virtual model can be used to predict size. The aim of this study was to quantify
the accuracy of the surgeon-validated plan prediction on a computed tomography (CT)-based
system. The clinical records of 336 cases (267 patients), operated using a CT-based
patient-specific instrumentation, have been reviewed for the size of implanted components.
Preoperative default planning (according to the preferences of the surgeon) and approved
planning have been compared with the size of implanted components for both the femur
and tibia. The prosthesis size, preplanned by the manufacturers, was modified by the
surgeon during the validation process in 0.9% of cases for the femoral component and
in 2.7% of cases for the tibial component. The prosthesis size, preplanned by the
surgeon after the validation process, was used in 95.8% for the femur and 92.6% for
the tibia. Concordance on the size of the surgeon-validated plan and the finally implanted
size was perfect for both, the femoral (κ = 0.951; 95% confidence interval [CI]: 0.92–0.98) and the tibial component (κ = 0.902; 95% CI: 0.86–0.94). The most frequent change of size (51%) was an increase
by one size of the planned tibial component. Planning of knee arthroplasty surgery
on a 3D virtual, CT-based model is useful to surgeons to help predict the size of
the implants to be used in surgery. The system we have used can accurately predict
the component size for both the femur and tibia. This study reflects a study of level
III evidence.
Keywords
patient-specific instruments - total knee arthroplasty - implant size - preoperative
planning
