Figure 9.

Patient with bilateral knee pain without history of trauma. Proton density fat saturated MR (top right) had shown a focal abnormal signal within the lateral femoral condyle and proximal tibia of the right knee with a differential of avascular necrosis (AVN), infarct or metabolic cause. On the single photon emission CT-CT, there is focal increased uptake of tracer seen in the right lateral femoral condyle, which corresponds to an area of faint sclerosis on the CT. Scan appearances in the right knee indicate a healing subchondral fracture likely secondary to AVN, and the increased uptake at this site correlates to the marrow oedema seen on MRI. Uptake in the tibial plateau is likely secondary to the medial meniscal degeneration.