Longitudinal gait analysis of pristane-induced arthritis. Time course of the print area (A) and the stance phase-fraction of total step duration (B) of paws of pristane-injected versus control rats. Mean values obtained for the gait variables of affected (n = 16) and unaffected (n = 8) paws are shown in black. Respective values of all paws of pristane-injected animals (n = 24) are also depicted for comparison. Arthritis scores of affected paws are depicted in red. Mean values ± SEM of paws were calculated and subjected to ANOVA with Dunnett's post hoc test to compare paws of pristane-injected animals with paws of control animals. * P < 0.05, ** P < 0.01. For longitudinal analysis within each group, locomotion and arthritis score was recorded prior to injection and was used as the baseline reading (Day 0). Comparisons with later time points were performed using paired t-tests. + P < 0.05, ++ P < 0.01, +++ P < 0.001. One representative out of two experiments is shown (C) Time course of the regularity index measured by the percentage of normal step sequence patterns in naive control rats (n = 8) and rats injected with pristane (n = 12). Overall arthritis scores of affected animals are depicted in red. The curves show mean values ± SEM. Differences to pre-morbid values were calculated using paired t-tests.