Before having arthroscopy should I have radiiologist interpreting knee mri?

To what end? Most mri's are read by radiologists. Did you get a copy of the report? The name at the bottom would be a radiologist. At the same time, your surgeon should also read the films and make surgical decisions from them. If you want another opinion, it should probably be from another surgeon to interpret the surgical indications.
See below. Any arthroscopic surgeon should be able to accurately interpret an MRI of the knee. If they are not able to interpret diagnostic studies, they should not be performing the surgey. Nevertheless, i would recommend an independent reading by a musculoskeletal radiologist. In my practice, mris are performed by independent radiology facilities , and readings are performed by the radiologist.
Yes. Ok. So as a Radiologist I may seem a bit biased, but if you have any uncertainty about the reason for an arthroscopic examination, then you should get a second opinion for your MRI study from an experienced Radiologist. This will reassure you that there are abnormal findings in your study that may be helped with arthroscopic treatment. Discuss the second opinion with your Surgeon.
Sure. Radiologists usually provide a report on any mri. However, radiologists do not have the benefit of actually examining the patient. I only recommend surgery when symptoms, physical exam findings, and MRI findings compliment each other and confirm a diagnosis amenable to surgical intervention.
MRI. It certainly cannot hurt to have another opinion on your MRI reading. Most orthopedists are adept at reading mris but i always like to see what the iradiologist reads on the mris that i order.