Usage of the L-shaped Caliper for Limb Length and Femoral Offset Measurement in Total Hip Arthroplasty

Abstract

We designed a caliper positioned parallel to the femoral axis during total hip arthroplasty, and evaluated its accuracy in comparison with the straight caliper employed previously. At the same time, we evaluated the degree of femoral offset.
The correlation between the limb length measured intraoperatively and that measured by radiography was improved by use of the new caliper (p < 0.01, r = 0.83), but the correlation with femoral offset was not so high. Although measurement of the limb length parallel to the femoral axis is accurate, but not for that of the degree of femoral offset. To measure femoral offset correctly, it is necessary to reproduce the pre-and post-measurement abduction positions.