Hospital bed height influences biomechanics during bed egress: A comparative controlled study of patients with Parkinson disease

Although a significant proportion of patient falls occur during egress from the hospital bed, the biomechanical adaptations during egress from different bed heights are still largely unknown. The purpose of this study was to evaluate the effect of hospital bed height on natural transition during egress in patients with Parkinson disease (PD). Twelve patients with PD and fourteen healthy elderly adults (HEA) were recruited and the natural transition during egress from three different bed heights (low, medium and high) were recorded for each participant using a motion capture system and force plates. The bed egress time, joint kinematics, ground reaction force and center of mass (CoM) were compared using a two-factor repeated ANOVA to determine the effects of three bed heights and two groups. The results showed that patients with PD had a significantly increased bed egress time, decreased peak of pelvis anterior tilt, hip flexion, and anteroposterior distance between pelvis center and CoM compared to HEA. Additionally, both PD and HEA groups increased the peak of trunk, hip and knee flexions to generate forward CoM momentum and joint torque to rise from a low bed height. These findings indicated that patients with PD invoked a more conservative movement pattern than HEA during egress to improve postural stability. The low bed height increased demands of balance and postural control during egress which exacerbates the risk of falls for patients with PD.