This lesion looks relatively benign and no additional imaging is needed unless pain is localized to this area and increasing, then possibly a bone scan.

The fat-fluid level tells you there is a fracture, but the fracture is not evident on radiographs so definitely needs additional imaging, and since it is mainly a bony problem, CT is the best choice.

This appearance suggests a popliteal aneurysm, for which more imaging is definitely needed, either ultrasound or MR.