Radiological and histological characterization of subchondral bone cysts in osteoarthritic joint. (A) Two-dimensional image of a subchondral bone cyst (SBC; dotted line) in a bone cylinder taken from the primary compressive region of osteoarthritic femoral head, from micro-computed tomography scan. (B) Three-dimensional reconstruction of the SBC (blue), from micro-computed tomography scan. (C) Osteoclastic bone resorption (arrowheads) in the trabeculae surrounding a SBC, from backscattered scanning electron microscope scan. (D) Histological features of new bone formation (arrows) on the surface of the trabeculae surrounding a SBC.