To explore the three angle degrees of kinematic characteristics of hip joint in the gait cycle: adduction/abduction, internal/external and flexion/extension during gait of healthy subjects by three-dimensional gait analysis system, furthermore, the kinematic parameters of the hip joint between the dominant and dominant legs were analyzed.

Thirty healthy subjects (15 male and 15 female) were recruited as the research objects. The kinematic data of hip joint in walking state were collected by three-dimensional gait analysis system. Paired sample t test was used to statistically analyze the kinematics data and motion range of the hip joint between the dominant leg and the non-dominant leg in the gait cycle, and the other parameters were analyzed by independent sample t test.

The hip joint movement showed regular changes in gait cycle. In the adduction/abduction degrees of freedom, the dominant leg and the non-dominant leg showed statistically significant difference in 41% to 64% of gait cycle (late standing and early swing), 50% in the late supporting phase (t=2.32, P=0.028), and the difference in the range of motion was also statistically significant (t=9.387, P< 0.05), but there was no statistically significant difference between sexes. In the internal/external rotational degrees of freedom, the gender differences in most phases of gait cycle were statistically significant, 50% in the late support phase (t=2.445, P= 0.018) and 62% in the early swing phase (t=2.540, P=0.014). In the comparison of the range of motion, the difference between the dominant legs was statistically significant (t=2.319, P=0.028), while the difference between the sexes was not statistically significant(P>0.05). In the flexion/extension degrees of freedom, the gender difference was statistically significant among 59%~86% of the gait cycle (including early swing phase, early swing phase and middle swing phase) ( 62% of the early swing phase: t=-2.371, P=0.021). In the comparison of dominant side and non-dominant side, there were significant differences in the flexion angle between 1%~39% (heel landing stage, load stage, middle standing stage, and late partial standing stage) and 76%~100% (middle swing phase, end swing phase) of gait cycle (31% in the middle support phase: t=3.024, P=0.005, the maximum flexion angle 89%: t=8.702, P<0.001). There was statistically significant difference between the dominant and non-dominant legs in the comparison of the range of motion (t=9.387, P<0.001)

The regular changes of hip joint kinematics in gait cycle of healthy subjects are showed in this study, which can provide reference for the research of hip joint disease motion characteristics. The impact of gender and dominant leg should be considered in hip gait analysis.