Simply put, "gait" is the way in which a person or animal walks. When pain, paralysis or tissue damage occurs, abnormal gait is the result. Loss of motor control will also result in a gait disorder. There are two major abilities essential to walking. The first, equilibrium, is the ability to assume an upright posture and maintain balance. Locomotion, the ability to initiate and maintain rhythmic stepping, is the second. However, although these two abilities are essential, there are many additional contributing factors involved. The musculoskeletal system must provide intact bones and well functioning joints as well as adequate muscle strength. Normal gait requires the proper functioning of the musculoskeletal system and the nervous system.
Three Fundamental Stages of Gait
Contact Stage
The contact stage begins with heel strike on the lateral border of the calcaneus. The tibia internal rotation occurs to the tibia as the foot pronates at the subtalar joint through the contact phase. Contact is made by the 5th metatarsal with the ground as the foot continues rolling medially until the metatarsals become fully loaded at the conclusion of the contact phase. The contact phase is designed to convert the foot into a mobile adaptor and shock absorbing mechanism.
Midstance Stage
The midstance phase converts the foot from a mobile adaptor into a rigid lever. The tibia externally rotates during this phase and the foot supinates at the subtalar joint preparing the foot for propulsive phase.
Propulsive Phase
Heel lift commences the propulsive phase. The subtalar joint should approach the neutral position just prior to heel lift. It is at this point that the forefoot and the rearfoot lock together to enable effective toe-off. Supination continues during toe-off with the resultant external tibial rotation.
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