Trigger point(s) and/or muscle inhibition may be worth a look at, but I would have thought that they would not produce the level of pain that the patient is experiencing.
I wondered if she sprained the ankle, as I just got a new patient with intense constant pain from such. I'm no expert here, but if her laces were loose the sprain could be inside loose shoes? the inversion also agittated the invertors, hence medial symptoms.
Mark here, coming from left field, does Juvenile R.A. present with intense pain like this? Or would it have been picked up on MRI? Just a thought.
Mark
Here is an interesting article to ponder regarding supination spasm of the foot.
I would check again for tarsal coalition...did the MRI cover the whole rearfoot and midfoot?? http://www.jbjs.org.uk/cgi/reprint/47-B/3/533.pdf
I currently have a adult patient with a supination spasm of the posterior tibial muscle that seems to be related to something happening in the posterior subtalar joint.
This is the first I have seen in 21 years of practice.
Local infiltrations of local anesthetic into the posterior subtalar joint reduces pain and spasm but have not yet seen anything on a few x-rays.
Casting improves pain and spasm, but does not resolve it.
Awaiting an MRI.
Sounds like a similar history.
Try sequential diagnostic local anesthetic injections into the joint spaces of the rearfoot.
I'll bet it reduces the spasm.
These are rare birds when you try to do a literature search for supination spasms.