Normal lower-extremity alignment parameters in healthy Southern Chinese adults as a guide in total knee arthroplasty

Alignment parameters in 199 healthy lower extremities of Southern Chinese adults and the parameters' anatomical influence were studied in a standardized frontal plane for the selection of the proper valgus angle of the distal femoral cut in total knee arthroplasty. The average hip-knee-ankle angle was 179.8 degrees +/- 2.4 degrees. The average femoral physiologic valgus angle was 5.1 degrees +/- 0.9 degrees (95% confidence interval, 4.9 degrees -5.2 degrees). The hip-knee-ankle angle showed a significantly inverse correlation with the femoral physiologic valgus angle. The results indicate that choosing 5 degrees as the valgus angle for the femoral distal cut in total knee arthroplasty is safe for most of Southern Chinese ethnicity, and it is reasonable to adjust the femoral valgus angle to 7 degrees or 3 degrees in the few patients with severe genu varum or genu valgum.