Figure 5
Gait changes occur before visible arthritis is apparent. (A) Time course of the print area and the duration of stance phase measured as the fraction of total step duration of a representative left hind paw after pristane-injection. (B) Photographic images of the left hind paw at characteristic time points (before pristane injection = Day 0, clinically unaffected joint showing gait changes = Day 11, onset of clinical PIA = Day 12, full-blown acute PIA = Day 16). Arrows show location of erythema and swelling on Day 12 and Day 16. (C) Comparison of day of onset of significant gait changes (defined by >5% reduction of print area or shortening of stance phase time versus pre-operative values) versus clinically apparent arthritis in paws with severe arthritis (arthritis score ≥5) reveals that print area reduction and stance phase shortening occur significantly before onset of apparent PIA. Data are presented as box plots. Lines within the boxes represent the median, boxes represent the 25th and 50th percentiles, and lines outside the boxes show the minimum and maximum values.