The epicondylar ratio can be reliably used on X-ray of the knee to determine the joint line.
Bernd LutzAngela TrubrichThomas KappeHeiko ReichelRalf BiegerPublished in: Archives of orthopaedic and trauma surgery (2018)
The ER can be determined reliably on MRI and X-ray images of the knee. The correlation of the ER in MRI and X-ray is fair.