Longitudinal monitoring of subchondral bone cysts (SBC) developing in the medial tibial plateau. Co-registered sagittal 9.4 Tesla MRI (a-c) and micro-CT (d-f) sections reveal the onset of SBC formation in conjunction with a breach of the subchondral bone plate (d - arrowhead), which never fully repairs over time. All SBC expanded over time, 4 weeks (wk) to 12 wk post surgery, and appeared to transition from a vacuous, fluid filled cavity (b - arrow) to a more fibrous filled region containing immature or disorganized osteoid (c, f - arrows). Scale bar = 2 mm. micro-CT, micro computed tomography; MRI, magnetic resonance imaging.