Abstract
Introduction
This study investigates and compares the accuracy of pre-operative templating from the AP and lateral radiographs in total knee arthroplasty.
Methods
Pre-operative radiographs from 478 patients undergoing primary total knee arthroplasty from September 2006 to April 2009 were reviewed. 154 had digital templating performed on both the AP and lateral radiograph The sizes templated for both the femoral and tibial components were recorded from the PACS archive. These were compared aginst the implanted femoral and tibial sizes taken from the theatre record.
A Z-score for two proportions was used to determine the level of significance of any difference in accuracy between the AP and lateral views for each component.
Results
The femoral component was templated accurately in 56 cases (36.4%) on the lateral view and in 48 (31.2%) on the AP. It was accurate to within 1 size for the femoral component in 125 cases (81.2%) from both the AP and lateral views. The tibial component was template accurately in 70 cases (45.5%) on the lateral view and in 78 (50.6%) on the AP. It was accurate to within 1 size in 139 cases (90.3%) on the lateral view and in 142 (92.2%) on the AP. The same size was templated for the femoral component in 111 cases (72.1%) and in 83 cases (53.9%) for the tibial component.
There was no statistical difference between the AP and lateral templating for either femoral or tibial component. The tibial component was templated significantly more accurately than the femoral component for the exact size (p= 0.016) and to within 1 size (p= 0.007).
Conclusions
There is a tendency for greater accuracy of femoral templating on the lateral radiograph and for tibial templating on the AP. Tibial templating is significantly more accurate than femoral templatin
