THREE-DIMENSIONAL ANALYSIS OF KINEMATIC AND KINETIC COORDINATION OF THE LOWER LIMB JOINTS DURING STAIR ASCENT AND DESCENT

Abstract

Being a common daily activity, stair locomotion places much higher loads on the lower limb than level walking does so a better understanding of the biomechanics of this activity is important for evaluation and treatment for patients with lower limb problems. The purpose of the present study was to investigate the three-dimensional dynamics and coordination of the joints of the lower limb during the stance phase of stair ascent and descent. Ten normal young adult subjects were recruited to ascend and descend stairs in a gait laboratory where the three-dimensional kinematic and kinetic data as well as muscle electromyography (EMG) were collected. The sagittal ranges of motion during stance phase of stair ascent were from 1.85° extension to 53.5° flexion for the hip, 13.1° to 60.1° flexion for the knee and 13.8° dorsiflexion to 14.0° plantarflexion for the ankle. Corresponding data for stair descent were 4.78( to 13.16( flexion for the hip, 8.3° to 77.6° flexion for the knee and 18.3° dorsiflexion to 27.4° plantarflexion for the ankle. Maximum extensor moments of 8.5% and 15.6% (Nm/BW/LL) were required at the hip and knee respectively during loading response while 19.4% (Nm/BW/LL) at the ankle shortly before toe-off. During stair descent, maximum extensor moments of about 4.4% were required at the hip during loading response and before toe-off while 13.3% and 15.2% (Nm/BW/LL) at the knee and ankle respectively before toe-off The joint angles, moments, and powers in the frontal and transverse planes were relatively small, except for hip abduction. The hip abductor moments and powers were significantly bigger than those of the knee and ankle in both stair activities. Joint powers and the corresponding muscle activation patterns in stair ascent were significantly different from those in descent, with concentric powers generated mostly during stair ascent and with eccentric powers stair descent. The differences of the movements of the lower limb during stair ascent and descent were due to different safety requirements and kinematic and kinetic constraints from the stairs. The complete description of the biomechanics of the lower extremity while performing stair locomotion will be helpful for the planning and evaluation of treatment programs for patients with lower limb problems.