Kinematics of lower extremity for the young and elderly Chinese population during squatting

The purpose of this study was to investigate the kinematics of the lower extremities of Chinese population during normal squatting activity. 25 young subjects (average age of 23.6 years) and 25 elderly Chinese subjects ((average age of 62.7 years) were recruited. With each subject´s six trials data collected, the means of the three-dimensional (3D) rotation angles of the ankle, knee, and hip joints of two groups were calculated and analyzed. The statistical analysis showed that there are significant differences for hip joints and no significant differences for the knee and ankle joints between the two groups. The maximal eccentric range of hip flexion/extension of 90.1° for the young group (P<;0.01) was compared to that of 160.9° for the elderly group. Thus, the elderly enjoys more hip flexion/extension angles than the young, with the squatting posture assumed. The mean range of motion (ROM) of knee flexion/extension was 136.4° for the young group and 137.7°(P>0.05) for the elderly group. The mean ROM of ankle flexion/extension was 33.0° for the young group and 33.1°(P>0.05) for the elderly group. The ROMs available for us to obtain in the experiment during squatting were greater than the reported ones achieved after joint arthroplasty. These data may be valuable in establishing a standard of designing lower extremity prosthesis and assessing effect of rehabilitation for the Chinese population.