Breadth of base whilst walking: effect of ageing and parkinsonism

Background: the effect of healthy ageing and of parkinsonism on breadth of base whilst walking had not been adequately documented. Design: height-specific reference ranges for mean foot separation at mid-swing were derived for males and females, age not proving to be a significant influence. Method: normative data were obtained from 164 healthy volunteers, and foot separation in idiopathic parkinsonism (99 patients) was characterized by comparison. Results: parkinsonism was associated with significantly greater within-and between-subject variability in foot separation. There was a linear trend from increased separation in those with bilateral signs but little functional impairment, to decreased separation in the severely impaired but not yet chair or bed bound. Foot separation was best explained by two clinical signs, rigidity and anatomical postural abnormality. A flexed posture was associated with increased separation, rigidity with decreased, the separation manifested being determined by the net effect. Conclusion: in early idiopathic parkinsonism, falling may depend on abnormal posture, and increased breadth of base be compensatory. Later, the decrement in foot separation may become a primary determinant of falls.