Knowledge Base

Paw Statistics

Body Dynamics

• Initial Contact At (s): Body Speed
• Stand / Stance (s): Body Speed Variation (%)
• Single Stance: Duration during which only one hind paw contacts the glass plate (contralateral hind paw off ground).
• Initial Dual Stance: First period in a hind-paw step cycle during which both hind paws simultaneously contact the glass.
• Terminal Dual Stance: Second period in a hind-paw step cycle during which both hind paws simultaneously contact the glass.

Interactive Hind Paw Footprint Measurement (Module)

• Max Intensity At (s): Time since run start at which maximum print intensity occurs.
• Max Intensity At (%): Max Intensity At expressed as a percentage of stance duration.
• Max Intensity: Time since run start at which maximum print intensity occurs.
• Min Intensity: Max Intensity At expressed as a percentage of stance duration.
• Mean Intensity: Time since run start at which maximum print intensity occurs.
• Mean Intensity of 15 Most Intense Pixels: Mean intensity of the 15 highest-intensity pixels of the print.

Step Sequence and Footfall Patterns

• Regularity Index (%): Number of Normal Step Sequence Patterns (NSSP) × 4 / Total paw placements × 100%. A value of 100% indicates fully coordinated gait. Used in spinal cord injury research.
• Footfall Patterns: Six recognised pattern families: Cruciate A (CA), Cruciate B (CB), Alternate A (AA), Alternate B (AB), Rotate A (RA), Rotate B (RB). Labelling is independent of which paw starts the run.
• Normal Patterns: Count of step cycles falling within one of the six recognised footfall pattern categories.
• Accounted Steps: Total number of steps used to determine footfall patterns.

Base of Support

• Base of Support — Front Paws: Mean Y-axis distance between the centres of the two front paws at Max Contact.
• Base of Support — Hind Paws: Mean Y-axis distance between the centres of the two hind paws at Max Contact.

Print Positions

• Print Positions: Distance between the ipsilateral front and hind paw in the same step cycle (X-axis at Max Contact). Positive = hind paw behind front paw; negative = hind paw in front of front paw.

Other Statistics

• Duration: Duration of the run based on selected steps (Data Segmentation profile).
• Average Speed: Average speed of selected steps (distance units/second).
• Maximum Variation (%): Maximum variation in average speed within the selected steps.
• Cadence: Steps per second, calculated from Initial Contact of the first to last selected step.
• Number of Steps: Total number of selected steps.
• Sciatic Functional Index (SFI): Functional recovery measure for the sciatic nerve. Uses Manual Print Length, Toe Spread, and Intermediate Toe Spread for experimental vs. normal contralateral hind paw. Calculated separately for rats (Bain 1989) and mice (Inserra 1998). Requires IFM module.
• Posterior Tibial Functional Index (TFI): Recovery measure for the tibial nerve branch. Same inputs as SFI. Requires IFM module.
• Peroneal Functional Index (PFI): Recovery measure for the peroneal nerve branch. Uses Print Length and Toe Spread. Requires IFM module.

Phase Dispersions

Phase Dispersions describe the temporal relationship between the placement of two paws within a step cycle, expressed as a percentage of the anchor paw's step cycle time. Six paw-pair combinations are reported. Range: −50% to +50% (CStat Mean). Values are circular statistics.

Paw Pair Combinations

• Diagonal Pairs: RF–LH and LF–RH (anchor = front paw).
• Girdle Pairs: LF–RF and LH–RH (anchor = left paw).
• Ipsilateral Pairs: RF–RH and LF–LH (anchor = front paw).

Phase Dispersion Statistics

• CStat Mean (%): Circular mean of phase dispersions (range −50% to +50%).
• AD (Angular Deviation): Measure of spread around the mean (equivalent to Standard Deviation in CatWalk ≤ 10.6).
• SD (Circular Standard Deviation): Alternative spread measure; ranges from 0 to ∞.
• R: Length of the mean vector (0–1); higher R = greater consistency of inter-paw timing across step cycles.
• Mismatches: Count of ANT (anchor, no target), AMT (anchor, multiple targets), and TNA (target, no anchor) occurrences.

Couplings

Couplings are computed the same way as Phase Dispersions but a target can never precede its anchor; values range from 0% to 100% (CStat Mean). Twelve paw-pair combinations are reported. The same statistics (CStat Mean, AD, SD, R, Mismatches) are available as for Phase Dispersions.

Support and Footfall Formulas

• Support Formula: Number of paws simultaneously on the glass plate in each section of a step cycle (e.g., 2–3–2–3–2–3–2–3).
• Footfall Formula: Alphanumeric notation indicating which specific paws are on the glass plate during each section.
• Standing On (%): Relative duration of simultaneous contact for all combinations: zero, single, diagonal, lateral, girdle, three, and four paws.

Group Statistics

Group statistics aggregate per-trial values by treatment group and time point combination. Available statistics: N, Mean (arithmetic or circular), SEM, CStat Mean, CStat R, CStat AD, CStat SD.

Charts: Bar chart (mean ± SEM) or Five Number Summary (box-whisker, minimum 4 trials required). Circular charts for Phase Dispersions and Couplings. Charts can be split by treatment group, time point, or both.

Research Applications

CatWalk has been validated and applied extensively across a wide range of preclinical research areas. The following disease models and research areas have been studied using CatWalk gait parameters.

Source: CatWalk XT 11.0 Technical Specifications, Noldus Information Technology