Can patients whose artificial knee is comprised of oxinium safely undergo an mri scan or is there an alternative?

Yes.: Knee prostheses are not a contraindication to MRI - however, the study will be very limited if trying to look at the knee with the prothesis because the metal in the prosthesis will warp the magnetic field.

Yes : The worry about mris and metal implants has to do with magnetic metals (ferromagnetic). Total and partial knee implants are made of cobalt chrome, titanium, oxinium ( oxidized zirconium), and polyethylene plastic. These are not iron containing magnetically charged implants so they are all safe in an mri. Pacemakers and defribulators, aneurysm clips can not go in mris.

Yes, but....: The problem with a knee replacement and then an MRI scan is more a technical problem with the scanner and images than a patient safety problem. The metal produces artifacts and distortions to the images, and may obscure important abnormalities. Similar problems can be seen with CT scans, although sometimes at different locations. The only thing to do is have a scan and see what it shows.