Child has jra and her ankle hurts often but mri showed no inflammation so what could be wrong? before mri rheumo noticed physical diff in movement

Not active: Mri only shows active inflammatory processes. The joint may not have been involved at that time, or it was not yet active enough to see. Also, some chronic inflammatory states are not well visualized on mri.

4: Most pain stems from mechanical, inflammatory, neurologic or functional causes. Mr is fairly good at finding inflammation if present. I doubt functional or neurologic pain and thus i would at mechanical causes. A pediatric orthopedic surgeon may be your best option for a diagnosis and treatment.