Insufficiency fractures involving the medial tibial condyles bilaterally showing hyperemia on the nuclear medicine bone scan and SPECT and then confirmed on MRI study.
The primary differential would be avascular necrosis, especially based on the clinical scenario, but the location in the medial tibial condyle, the symmetry, and the intense capitation on the bone scan/SPECT go against this diagnosis. MRI has further shown the fracture lines.
Insufficiency fractures are a type of stress fracture, which are the result of normal stresses on abnormal bone. This diagnosis was achieved based on the clinical data and imaging appearances. These fractures are usually not identified on conventional radiographs. Radionuclide bone scan, and especially MRI are the modalities of choice when assessing this condition.