Aggrecan fragment concentrations in the study groups. Concentrations of (a) ARGS fragments, (b) sulfated glycosaminoglycan (sGAG), and (c) aggrecan in the study groups healthy knee reference (REF), acute inflammatory arthritis (AA), acute knee injury (AI), chronic knee injury (CI), and knee osteoarthritis (OA). The boxes define the 25th and 75th percentiles with a line at the median, error bars defining the 10th and 90th percentiles and circles represents individual outliers. Note that in panel (a) the median level of the chronic injury group is the same as the lower limit of the box; 0.5 pmol ARGS/ml. After Bonferroni correction, P values below 0.013 are considered significant to retain the 0.05 overall significance level.