How do they do a bone scan on knees?

Painless: Radioactive tracer injected in vein. Small needle stick. Return a few hours later and stand in front of scanning machine for a few minutes. Bones are scanned while you stand.

Bone scan...: For most bone scans, a tracer called technetium mdp is injected intravenously and then delayed images of the desired area are taken. The patient is usually positioned supine on the table and the detectors of the gamma camera are oriented to achieve the appropriate views.

A radionuclide: is injected intravenously, and immediate and delayed images are usually performed by placing you on the camera(gamma camera).