Certain disorders of motor and sensory function manifest themselves most clearly as impairments of upright stance and locomotion; their evaluation depends on knowledge of the neural mechanisms underlying the peculiarly human function of standing and bipedal walking. The analysis of stance, carriage, and gait is a rewarding exercise; with some experience, the examiner can sometimes reach a neurologic diagnosis merely by noting the manner in which the patient enters the office. Considering the frequency of falls that result from gait disorders and their consequences, such as hip fracture, and the resultant need for hospital and nursing home care, this is an important subject for all physicians. The substantial dimensions of the social and economic problem of falls and the elderly have been described by Tinetti and Williams.
Obviously, gait varies considerably from one person to another and it is a commonplace observation that a person may be identified by the sound of his footsteps, notably the pace and the lightness or heaviness of tread. The manner of walking and the carriage of the body may even provide clues to an individual's personality and occupation. Sherlock Holmes expressed pride in his talent for reading such clues. It is said that Charcot could often make the correct diagnosis, even before seeing the patient, based on the sound of patient walking down the hallway on the way to the examining room. Furthermore, the gaits of men and women differ, a woman's steps being quicker and shorter. The changes in stance and gait that accompany aging—the slightly stooped posture and slow, stiff tread as described in Chap. 29, on aging—are so familiar that they are not perceived as abnormalities.
The normal gait seldom attracts attention but it should be observed with care if slight deviations from normal are to be appreciated. The body is erect, the head is straight, and the arms hang loosely and gracefully at the sides, each moving rhythmically forward with the opposite leg. The feet are slightly externally rotated, the steps are approximately equal, and the medial malleoli almost touch as each foot passes the other. The medial edges of the heels, as they strike the ground with each step, lie almost along a straight line. As each leg moves forward, there is coordinated flexion of the hip and knee, dorsiflexion of the foot, and a barely perceptible elevation of the hip, so that the foot clears the ground. Also, with each step, the thorax advances slightly on the side opposite the swinging lower limb. The heel strikes the ground first, and inspection of the shoes will show that this part is most subject to wear.
The normal gait cycle, defined as the period between successive points at which the heel of the same foot strikes the ground, is illustrated in Fig. 7-1, based on the studies of Murray and coworkers, and of Olsson. In this figure, the cycle is initiated by the ...