Coronal Alignment of the Lower Limb and the Incidence of Constitutional Varus Knee in Korean Females

PURPOSE In total knee arthroplasty (TKA), it is important to restore neutral mechanical alignment. The purpose of this study was to assess whether the lower limb alignment is neutral in healthy Korean females and investigate the incidence of constitutional varus knees among them. MATERIALS AND METHODS Weight-bearing full-leg standing radiographs were obtained from 118 healthy females between the ages of 20 to 39 years. One radiologist and two orthopaedic surgeons measured the hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and femoral anatomic mechanical angle (FAMA) on the radiographs and compared with the traditional gold standard HKAA of 0°, MPTA of 3° varus, and FAMA of 6°. RESULTS The interobserver reliability of the three independent observers was high (p<0.001). The HKAA of the study subjects (1.35°±2.04°) was significantly different from the standard HKAA of 0° (p<0.001), but no statistically significant difference was observed in the MPTA (-3.18°±1.61°) and FAMA (5.99°±0.70°) from the standard values (p=0.083 and p=0.887, respectively). The incidence of constitutional varus alignment was 20.34%. CONCLUSIONS In Korean females, the mechanical axis of the lower limb was not neutral and the incidence of constitutional varus alignment was slightly higher than that in Western females. We believe that these findings should be taken into consideration in planning reconstructive surgery of the knee, such as TKA, unicompartmental knee arthroplasty, and high tibial osteotomy.