Component Sizing In Total Knee Arthroplasty Research Articles

Comparative study of femoral component sizing in TKA between custom cutting block and intraoperative anterior reference sizing

BackgroundCorrect sizing of prostheses is a considerable factor regarding function and successful rate of total knee arthroplasty (TKA). The purpose of this study is comparing the accuracy of CT-based preoperative sizing in patient-specific guide (PSG) with the conventional femoral component-sizing instrument. MethodsFifty-four patients underwent TKA with CT-based PSG. Preoperative sizing was compared to the component size measured intraoperatively by conventional anterior reference femoral-sizing instrument. The actual sizes of implanted components were also recorded to analyze the accuracy of each measurement. ResultsBy comparing to CT preoperative planning, the measurement of femoral size with the conventional anterior reference instrument showed 55.6% of equivalent size, 37% of increased size and 7.4% of decreased size with interclass correlation of 0.914 (0.852–0.950). The measurement by two surgeons showed 42.6% and 57.4% equivalent to the actual size (53.7% and 38.9% larger sizes). The accuracy of CT preoperative sizing in femoral component on comparing to the actual size was 96.3%. ConclusionAccuracy of femoral component sizing with a conventional instrument remains questionable. It might lead to an oversized component. The accuracy of sizing in PSG is improved due to the advantage of preoperative CT sizing.

Component sizing in total knee arthroplasty: patient-specific guides vs. computer-assisted navigation

Patient-specific guides (PSG) and computer-assisted navigation (CAN) are technologies that have been developed to improve the accuracy and reproducibility of total knee arthroplasty (TKA). The purpose of this study is to compare the methodology by which a PSG system and an intraoperative navigation system (CAN) perform an anatomical registration and correctly predict femoral component size in TKA. One hundred and eleven PSG TKA were performed, 30 of which were concurrently evaluated with CAN. PSG-predicted and CAN-predicted femoral component size were compared with the actual component selection. The process by which PSG and CAN determines component sizing was evaluated. The PSG system was both more accurate and more precise than the CAN navigation system in predicting femoral component size in TKA. In this study, the surgeon's final component selection was more likely to be in accordance with the PSG rather than the CAN sizing algorithm. This study suggests that intraoperative surface registration may not be as accurate as preoperative three-dimensional magnetic resonance imaging reconstructions for establishing optimal femoral component sizing.

Analysis of the Relationship between Posterior Cruciate Ligament Preservation and Femoral Component Sizein Total Knee Arthroplasty

Purpose : How PCL preservation affects the selection of femoral component size in total knee arthroplasty. Materials and Methods: One hundred and fifty-seven patients, two-hundred and twenty-two knees, underwent total knee arthroplasties with Scorpio®. One hundred and eighteen knees underwent PCLpreserving procedures, and one-hundred and four knees underwent PCL-substituting procedures. For minimization of error, we performed soft tissue balancing and then bone cutting by a Linker system with certain posterior slope (≤3˚). We compared the sizes of the femoral components between the PCL-preserving and PCL-substituting procedures in order to determine how flexion gap differences affect femoral component sizes (Wilcoxon signed rank test). Results : With a certain minimal posterior slope (≤3˚), the PCL-preservation procedure led to selection of a 2.4 mm smaller femoral component than the PCL substituting procedure (p＜0.05). Conclusion : Selection of femoral component size was affected by PCL preservation, and the size of the femoral component was decreased in the PCL preservation group.