ROTATIONAL ALIGNMENT OF THE FEMORAL COMPONENT IN TOTAL KNEE ARTHROPLASTY FOR VARUS OSTEOARTHRITIS OF THE KNEE; A RETROSPECTIVE STUDY

Abstract

Background and Aims: Achieving proper axial rotational alignment of the femoral component for varus knees is a critical step in total knee arthroplasty (TKA). Trans epicondylar axis (TEA) is the most reliable reference for alignment of femoral component. Yet, nding the exact location is sometimes difcult and time consuming. The aim of this study was to determine the correlation between the TEA and posterior condylar line reference (PCL) in varus knees. Besides, the other aim of this study was to nd the relationship between lateral distal femoral angle (LDFA) and femoral component external rotation (ER) measured intraoperatively. Material and Methods: This retrospective study was conducted on patients who were candidates for total knee arthroplasty from May 2016 to December 2019. LDFA, VA were calculated based on hip-to-ankle (HTA) radiographs before the surgery. All patients underwent TKA through an anterior midline incision. ER was calculated by determining TEA intraoperatively. All data were entered into SPSS software for data analysis. Results: One hundred and four patients were included in the nal analysis. Nineteen patients (18.3%) were male and 85 out of 104 (81.7%) were female. (P value = 0.001). No signicant relationship between the amount of ER measured during surgery and the amount of varus angle in varus knees was observed. Furthermore, there were no correlations between ER and LDFA in varus knees. Conclusion: Adjusting femoral component in 3 degrees external rotation relative to posterior condylar line reference achieves proper rotational alignment of the femoral component in the axial plane in varus knees. Also, the lateral distal femoral angle measured preoperatively from knee radiographs is not a predictor of ER in varus knees