Analysis of a patient's gait (the way a person walks) can reveal biomechanical deficits that could be addressed by physical therapy, prescribed medical equipment, interventional procedures, or even surgery. While a gait defect alone does not warrant treatment, the combination of pain and neurological deficits from nerve involvement, including muscle weakness that results in a gait deficit, can all improve with proper management.
We must distinguish between a gait abnormality, which is caused by a particular myotomal deficit that is either compensated by other myotomal activity or not compensated, versus an antalgic gait, which is an inconsistent alteration in gait in a nonmyotomal pattern that serves as an expression of the degree of pain.
Before a practitioner can analyze gait, understanding the basic features of gait is paramount so that a deficit can readily be identified.
Stride length: The linear distance between any point along the contact surface of the foot with the ground with the same point of contact of the same foot with the ground after taking two steps. For example, the distance from right heel strike to the next right heel strike is the stride length. Normal stride length is approximately 56 inches. (See Fig. 5-1.)
Stride length, step length, and step width.
Step length: The longitudinal (the net direction of ambulation) projection of the linear distance between any point along the contact surface of the foot with the ground with the same point of contact of the contralateral foot with the ground after taking one step. For example, the longitudinal distance from right heel strike to the next left heel strike is the step length. Not taking hypotenuse distances in consideration, roughly two step lengths equal one stride length. Normal step length is approximately 28 inches. (See Fig. 5-1.)
Step width: The lateral (orthogonal to the longitudinal direction) projection of the linear distance between any point along the contact surface of the foot with the ground with the same point of contact of the contralateral foot with the ground after taking one step. Normal step width is approximately 3 inches. This measurement is also known as the walking base. (See Fig. 5-1.)
Gait cycle: All the musculoskeletal activities that occur during the time it takes to traverse one stride length. The gait cycle consists of the stance phase and the swing phase.
Cadence: The number of steps per minute. Normal cadence is approximately 115 steps per minute.
Normal walking speed: Approximately 80 meters per minute or 3 mph.
Center of gravity: The center of gravity for a normal human standing upright is located approximately 5 cm anterior to the S2 vertebral body. ...