Gait analysis plays an important role in the assessment of neurological function in many disease models. In this review, we focus on the newly developed CatWalk system for gait analysis. CatWalk was originally developed as a tool to enhance assessment of functional outcome in spinal cord injury (SCI) models. Although it is also of value in models of among others (neuropathic) pain and peripheral nerve damage, we will limit ourselves to its use in SCI models in this review. The system is positioned against well-established locomotor function tests, and it is indicated how CatWalk can enhance the usefulness of such tests. Development of the system started with the idea that it should enable objective assessment of coordination, and powerful measures of coordination are nowadays included in the analysis options provided by CatWalk. Therefore, a major part of this review is devoted to the history and meaning of these coordination measures.

The Basso, Beattie and Bresnahan (BBB) locomotor rating scale is the most widely used open field test and has been accepted as a valid way to assess locomotor function after spinal cord contusion injury in the rat. A limitation within the BBB locomotor rating scale is the correct assessment of forelimb (FL)-hindlimb (HL) coordination. This limitation can have major implications for the final assessment of locomotor function. In the present study, we show an objective method to assess coordination based on the regularity index (RI), achieved through the use of the CatWalk method. The RI grades the degree of coordination as the result of the number of normal step sequence patterns multiplied by four and divided by the total amount of paw placements. Using the RI, single walkway crossings can be objectively analyzed on coordination. Integration of the CatWalk based coordination into the BBB scale indicates that objective analysis of coordination results in reliable and more sensitive assessment of locomotor function. This new method has been tested successfully in determination of positive effects of enriched housing on functional recovery after spinal cord injury (SCI).

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