Gait analysis as a correlate of pain induced by carrageenan intraplantar injection.

The aim of this study was to investigate whether gait changes occurring during the development of carrageenan induced rodent paw inflammation could be measured to provide an objective marker of persistent pain. The objectives were to measure hind limb tibiotarsal joint diameter as an indication of inflammatory oedema and to analyse gait during the development of the carrageenan induced persistent pain. Rear paw intraplantar injection of 6 mg (150 microl) lambda-carrageenan resulted in significant swelling of rear limbs at 90 min (P=0.002). Analysis of gait, using video recordings of spontaneous animal ambulations demonstrated significant changes in gait over a 90-min period. These were primarily changes in temporal measures of gait and consisted of a reduction in velocity (P=0.005) and stride length (P=0.006) and increase in dual stance time (P=0.009). It is hypothesised that the temporal and spatial changes in gait observed in this model of acute inflammatory hyperalgesia may have been due to avoidance of the normally non-noxious mechanical stimulation induced by walking. It is suggested that gait analysis may be a suitable method for measuring early behavioural change associated with inflammatory hyperalgesia.