A common old school technique for treating Tarsal Tunnel is cortisone shots. The science behind it is fine, if inflammation is causing the nerve to be impinged the cortisone shot will calm the inflammation thus reducing the tarsal tunnel sympatomoly for a limited period of time. However, do the positives of this injections outweigh the negatives over a prolonged period of time?
We know that by injecting steroid into the region specifically near a tendon it will weaken the tendon and increase the chance that the tendon may rupture or team. The Tibialis Posterior tendon runs parallel to the Tarsal Tunnel, a cortisone shot could lead to deleterious effects on the Tibialis Posterior tendon and any injury to that tendon would have negative sequalea down the road.
The other risk is we all know the steroid will precipitate where it is injected. So essentially you are dealing with a compressive symptom for some structures and adding foreign bodies to the area. Think about it this way, if you were doing a Tarsal Tunnel release and came upon steroid precipitate would you remove it or leave it in there. Of course you would remove it, so why are you injecting it in there in the first place.
Third, look at the causes of Tarsal Tunnel syndrome. What exactly does a cortisone shot treat???? The main causes of Tarsal Tunnel are compression from a cyst such as ganglion, another space occupying lesion, system inflammation, unknown etiology. A Cortisone shot is not a treatment for any of these. So by giving a cortisone shot for Tarsal Tunnel you are increasing risk for a patient while not really treating any of the underlying problems.