Relationship between trunk stability during voluntary limb and trunk movements and clinical measurements of patients with chronic stroke.

[Purpose] The purposes of this study were to investigate differences between patients with chronic stroke and age matched healthy controls in trunk stability, by assessing the kinematics of the center of mass and moving body segments during voluntary limb and trunk movement, and the relationship between trunk stability and clinical measurements. [Subjects and Methods] Fifteen stroke patients and 15 age- and gender-matched healthy subjects participated. Each subject performed flexion of the hip and shoulder of the non-paretic or matched side as fast as possible, as well as trunk flexion and extension at a self-selected speed. A Qualisys motion system was employed to track the kinematics of the trunk and limbs. [Results] Patients presented larger mediolateral displacement of the center of mass during all limb and trunk movements, and larger velocity of center of mass during hip flexion movement. Healthy subjects showed greater movement velocity during shoulder flexion, trunk flexion and extension. Patients' clinical measurements only correlated with movement characteristics during voluntary trunk motions. [Conclusion] Trunk stability in patients with chronic stroke was compromised during voluntary trunk as well as non-paretic limb movements, and the voluntary trunk movements reflected the trunk deficits measured using clinical measurements. Rehabilitation of patients with chronic stroke should include programs to improve trunk stability.