Fig. 4.

Microanatomical damage observed in histopathologic analyses of the PCL-SEC. (A) Fissuring of the collagen matrix (arrows) in the PCL is a feature commonly observed in the samples we studied. (B) Accumulation of myxoid material (arrow) in the fissured collagen matrix. (C) Tide mark reduplication (arrows) at the site of insertion was a common observation. In this case there is new bone formation in between the tide marks and evidence of cell necrosis. (D) Extensive neovascularisation (arrows) indicative of a reparative process observed at the PCL enthesis. (E) Fibrillation of the cartilage surface and (F) chondrocyte clustering (arrow) observed in the accessory sesamoid fibrocartilage of the PCL-SEC, both features typically associated with OA. Scale bars, A and B = 500 μm, C–F = 200 μm.