Femur rotational alignment in total knee arthroplasty: Delphi consensus statements from European knee society (EKS)

Proper rotational alignment of the femur components represents one of the key factors for the functional outcome of patients after total knee arthroplasty (TKA). Recent 3-D imaging data have shown a wide variability of the distal femur bony anatomy in the axial plane. The identification and intraoperative correction of these bony torsional deformities remain controversial. During the last decades various bony landmarks and surgical techniques have been proposed for proper femur rotational alignment but there is no consensus or evidence which method will be the best.This study employs a Delphi consensus methodology among European Knee Society (EKS) experts to address key questions regarding femur rotational alignment in TKA. Through a systematic literature review and expert discussions, a strong consensus was achieved on three main points: (1) Proper femoral rotational alignment must establish a balanced flexion gap and ensure proper patella tracking through the 3-D positioning of the trochlear groove. There is no consensus or evidence indicating whether the transepicondylar or trans-cylindric axis is the best compromise for the TKA flexion/extension axis. (2) For the three main techniques (measured resection, balanced flexion gap and combined/hybrid) and the new personalized alignment philosophies, no agreement on the best femoral rotational alignment exist. (3) Computer-Assisted Surgery (CAS) techniques using 3-D imaging preoperatively can help to identify the key rotational bony landmarks. Until now CAS has not delivered conclusive data to link these pre- and intraoperative findings to the clinical outcome to allow any recommendation for proper rotational alignment of the femur.This Delphi consensus statement summarizes the controversies, current practices, and evidence on the three key questions regarding proper femoral rotational alignment. There is a need for further high-level studies to identify the correct individual femoral rotational alignment to achieve better TKA outcomes.