A Method for Location of the Center of the Femoral Head During Total Knee Arthroplasty

Abstract

Purpose: To find a practical method to locate the center of femoral head during total knee arthroplasty when the extramedullary alignment guide has to be used. Materials and
Method: The distance between the Anterior Superior Iliac Spines (ASIS) and their distance from the vertical lines from the center of the femoral heads were measured on the AP pelvic radiographs of 56 female and 66 male patients. The obtained values were analyzed with correlation and regression analysis.
Results: Correlation analysis reveaIed that distance between the ASISs is positively correlated with the distance from the ASIS to a vertical line from the center of the femoral head on the same side. Using regression analysis, the latter distance was calculated for varying distances between two ASISs and a table was formed. The calculated values were within 1 cm of the measured values for 97% of the patients.
Discussion: When the extramedullary alignment guide is used during total knee arthroplasty, the center of the femoral head can be located easily and correctly by measuring the distance between the ASISs. This method saves the time and radiation exposure when radiography is used for the same purpose.