Knowledge Base

Stance Parameters

Single Stance

Single Stance is the duration (in seconds) of ground contact for a single hind paw (Coulthard et al., 2002, 2003). It is used for gait analysis in pain models. In CatWalk XT, Single Stance is the part in the step cycle of a hind paw where the contralateral hind paw does not touch the glass plate.

Initial Dual Stance

Dual Stance is the duration (in seconds) of ground contact for both hind paws simultaneously (Coulthard et al., 2002, 2003). Dual Stance is used for gait analysis in pain models. In CatWalk XT, a distinction is made between Initial Dual Stance and Terminal Dual Stance. Initial Dual Stance is the first time in a step cycle of a hind paw that the contralateral hind paw also makes contact with the glass plate.

Terminal Dual Stance

Terminal Dual Stance is the second time in a step cycle of a hind paw that the contralateral hind paw also makes contact with the glass plate. Note that the Terminal Dual Stance for a hind paw is the Initial Dual Stance for the successive step cycle of the contralateral paw.

Single and Dual Stance values are only calculated if the contralateral hind paw has been placed on the glass plate before and after a step cycle of the other hind paw.

Body Speed Parameters

Body Speed

The Body Speed of a step cycle of a specific paw is calculated by dividing the distance that the animal's body traveled from one initial contact of that paw to the next by the time to travel that distance.

Body Speed Variation

Body Speed Variation (%) is calculated by dividing the absolute difference between the Body Speed and the Average Speed of a run by the Average Speed.

Step Sequence

The Step Sequence sheet contains information on the order in which the four paws are placed. To view it, choose Analyze > View Run Statistics and under Statistics click Step Sequence.

Step Sequence

The Step Sequence lists the order in which the paws were placed on the glass plate. This order determines the footfall pattern that can be assigned.

Codes

Each Code corresponds to a particular paw:

• 1 = Left Hind (LH)
• 2 = Left Front (LF)
• 3 = Right Hind (RH)
• 4 = Right Front (RF)

The Codes are used to create the Footfall Patterns diagram.

Patterns

This row contains the abbreviations of the assigned footfall patterns. The colors of the cells correspond to those in the Footfall Patterns diagram.

Normal Patterns

This is the number of Step Cycles that fall within one of the footfall pattern categories.

Accounted Steps

This is the number of steps that was taken into account to determine the footfall patterns.

Regularity Index (%)

The Regularity Index expresses the number of normal step sequence patterns relative to the total number of paw placements. The formula is:

Regularity Index = (NSSP × 4 / PP) × 100%

where NSSP is the number of normal step sequence patterns and PP is the total number of paw placements.

The Regularity Index does not indicate whether the subject walks with the same pattern throughout. If the footfall pattern changes during a run (for example, from AA to AB), the Regularity Index is not affected.

The Regularity Index (RI) is used in research on spinal cord injury. It is a fractional measure of inter-paw coordination. In healthy, fully coordinated animals its value is 100%. For example, one week after rats were subjected to a transection injury, the RI decreased from 100% (pre-treatment) to approximately 80%, and increased again to 90% after 4 weeks (Hamers et al., 2001).

Additional Visualizations

In the Step Sequence sheet, when you click a Code or a colored cell, the following occurs:

• The Print View highlights the corresponding print.
• The Timing View highlights the start and end time of the stand of that paw.

To create footfall pattern diagrams, select Analyze > View Run Visualizations and under Visualizations click the Footfall Patterns tab.