Biomechanics of Normal vs Pathological Neurological Gait
The human gait cycle is an intricate sensory-motor sequence composed of two primary intervals: the stance phase (representing approximately 60% of the stride), requiring profound lower limb stability and weight acceptance, and the swing phase (40%), demanding active limb shortening, hip flexion, and precise foot clearance.
When central or peripheral nervous system lesions occur, this harmonious kinematic chain disintegrates. In hemiplegic stroke survivors, impaired hip extensor control and quadriceps spasticity often provoke violent knee recurvatum (hyperextension) during midstance, while ankle dorsiflexor weakness impairs ground clearance during swing. To prevent the paretic toes from dragging, the patient instinctively initiates 'circumduction gait' — swinging the paralyzed leg outward in a wide lateral arc using excessive pelvis elevation (hip hiking).
Conversely, in Parkinson's disease, patients exhibit a stooped, festinating gait characterized by rapid, diminutive steps and loss of reciprocal arm swing. In cerebellar ataxia, patients present with an irregular, wide-based, drunken-like staggering gait. Bidaya clinicians conduct comprehensive qualitative and quantitative observational gait analysis in the patient's home, isolating specific kinematic deficits and designing targeted interventions rather than encouraging unstructured, compensatory walking.
