Anatomical landmarks of the distal femoral condyles are not always parallel to the tibial bone cut surface in flexion during total knee arthroplasty.

•Soft tissue balancing of the knee is crucial for total knee arthroplasty.•The flexion joint gap was measured using three measured resection techniques.•An outlier in the flexion joint gap (>3.0°) was observed in about 30% of cases with each technique.•Anatomical landmarks of the distal femur are not always parallel to the tibial bone cut surface in flexion.