Cryotome type cm3050s

Following intraoperative resection, the tissue was transported and stored in serum-free Dulbecco's Modified Eagle's Medium (Gibco, Life Technologies, Darmstadt, Germany) with 2% (v/v) penicillinstreptomycin and 1.2% (v/v) amphotericin B. Two types of tissue sections were used: perpendicular sections (side view) and tangential sections (top-down view). For the side-view analysis, cartilage-bone cuboid samples (~1 cm in width, 3-4 cm in length) were cut from the resected condyle along the kinematic uniaxial movement direction of the knee. These cuboids were fixed in 4% (w/v) paraformaldehyde/ phosphate-buffered saline (PBS) (pH 7.0) for 24 hours at 4°C, followed by decalcification in 20% (w/v) ethylenediaminetetraacetic acid in PBS for several days at 37°C, with the solution being changed every other day. Following decalcification, samples were cut at a thickness of 35 μm with a Leica cryotome type CM3050S (Leica Biosystems, Wetzlar, Germany). For the side-view analysis, cutting was performed perpendicularly to the articular surface to obtain a full-thickness view of all cartilage layers, including the subchondral bone in a single lateral view (Figure S2B). Sections for the top-down views were performed directly on the resected tissue from the femoral condyle at 35-µm thickness in parallel to the articular surface (Figure S2C).