Fig. 1

Representative images, taken from full-thickness tear group 4, of parameters evaluated via histological score (HS). a Hypertrophy of synovium (H&E staining). Up to 4 layers of synoviocytes are present, HS 3. b Number of fibroblasts with rounded nuclei (H&E staining) was greatly increased in the whole tissue, HS 3. c Fatty metaplasia (H&E staining), when locally detected, HS 2. d Chondral metaplasia (Alcian Blue staining) in entire tissue, HS 3. e Neoangiogenesis, as an indicator for new vessel formation (α-SMA staining, red signal), HS 3. f Number of immune cells (CD45 staining, red signal) inside the tissue and in high numbers, HS 3. g Occurrence of villi as a sign for chronic processes (H&E staining), HS 3. h Occurrence of few nerve fibers (S100 staining), HS 2. For comparison, a “healthy” bursa from group 1 is depicted in (i) and a bursa from full-thickness SSP tear group 4 undergoing chronic changes is depicted in (j) (H&E staining)