1. Histopathological subgroups in knee osteoarthritis
L.A. Wyatt, B.J. Moreton, P.I. Mapp, D. Wilson, R. Hill, E. Ferguson, B.E. Scammell, D.A. Walsh 
Osteoarthritis and Cartilage 
Volume 25, Issue 1, Pages (January 2017)
DOI: /j.joca
Copyright © 2016 Osteoarthritis Research Society International Terms and Conditions

2. Fig. 1
Histological appearances of the medial tibial plateaux (A–F) and synovium (G–H). Articular cartilage surfaces displayed varying degrees of loss of cartilage surface integrity; from mild clefts (A) to the articular surface to deep clefts and severe cartilage loss (B). Inset of (B) chondrocyte cloning is observed (arrows). Proteoglycan content ranged from normal to severe loss (C). Channels frequently breached the tidemark between calcified and non-calcified cartilage (D). Subchondral bone marrow spaces contained normal fatty tissue in the majority of cases (E), whereas in some cases this was replaced by fibrovascular tissue (F). Inset of (F); high power image of the area indicated by the dotted box. In the majority of cases examined the synovium was normal (G); however in some cases mild, moderate or severe inflammation was observed (H). Dotted circle in (H) indicates perivascular lymphoid aggregate. Visualised with haematoxylin and eosin stain (A, B, D–H) or Safranin-O Fast Green (C).
Osteoarthritis and Cartilage  , 14-22DOI: ( /j.joca )
Copyright © 2016 Osteoarthritis Research Society International Terms and Conditions

3. Fig. 2
Histological features of early OA. (A): Prevalence of pathological features observed in knee tissue collected from 343 PM cases. Histopathological features towards the left were most commonly observed and might be normal or indicative of early OA. Features towards the right might be later features of OA. Abbreviations: cart = cartilage surface integrity, prot = proteoglycan loss, chon = chondrocyte morphology, tide = tidemark breached, oste = osteophytes present, syno = synovial inflammation, bone = subchondral bone marrow replacement by fibrovascular tissue. Chondrocyte scores are compressed. Each bar represents cumulative percentages for each histological measure e.g., cart ≥1 = percentage of cases that had a cartilage surface integrity score of 1 or above (i.e., between 1 and 6) etc. Separately, histopathological differences were compared between non-arthritic controls, chondropathy/osteophyte and end-stage OA cases for cartilage surface irregularity scores (B), proteoglycan score (C), synovitis score (D), chondrocyte morphology score (E), bone marrow replacement (F) and tidemark breaching (G). Data presented as mean (+s.e.m). Differences between groups were compared using multinomial regression analysis adjusted for age and gender. *P < 0.05, **P < 0.01, ****P < 
Osteoarthritis and Cartilage  , 14-22DOI: ( /j.joca )
Copyright © 2016 Osteoarthritis Research Society International Terms and Conditions

4. Fig. 3
Histopathological appearance of the synovium from each of the three histopathological subgroups. Class 1; normal synovium, grade 0 (A), Class 2; mild inflammation, grade 1 (B), Class 3: moderate inflammation grade 2, dotted circles indicate small cluster of inflammatory cells (C). Arrows indicate synovial lining. Pictures presented represent median synovitis scores for each subgroup. Haematoxylin and eosin stain.
Osteoarthritis and Cartilage  , 14-22DOI: ( /j.joca )
Copyright © 2016 Osteoarthritis Research Society International Terms and Conditions