Gender and age-related differences in axial alignment of the lower limb among healthy Japanese volunteers: comparative and correlation study.

A cross-sectional study was designed for this investigation using a healthy Japanese population. The objectives of this study were to confirm gender and age-related differences in axial alignment of the lower limb, and to investigate the correlation between femorotibial angle and axial alignment of the lower limb among a healthy Japanese population. Although axial alignment of the lower limb has been defined as one of the associating factors for osteoarthritis of the knee along with varus and valgus deformity, the results in the literature are inconsistent. Since there is gender difference in femorotibial angle, axial alignment of the lower limb should show the difference if it is an associating factor for osteoarthritis of the knee. Few studies have been conducted to investigate gender difference in axial alignment of the lower limb. One hundred and forty four healthy Japanese subjects took part in the study. Reliable clinical methods of measuring femoral torsion, tibiofibular torsion, rotational range of motion of the hip and knee joints, and femorotibial angle were employed utilizing a digital inclinometer. Two way ANOVA and Pearson product-moment correlation analysis were used for statistical analyses. Axial alignment of the lower limb was different between genders (p<0.05). An age-related difference was also shown in hip rotation (p<0.05). Further, the femorotibial angle was significantly correlated with hip and knee joint rotation (p<0.05) in older males and younger females. This study implied that axial alignment of the lower limb may be related to deformity of the knee joint.