Magnetic resonance imaging of the foot and ankle.

Magnetic resonance imaging (MRI) of the foot and ankle is useful for the diagnosis and staging as well as the surgical planning of multiple disorders: first, for osseous injury, particularly stress fractures and occult fractures, which appear like bone bruises but behave more like fractures. Then, for the Achilles tendon, MR is useful for staging the chronicity and extent of damage, as well as whether the tendon can be surgically repaired or reconstructed. For the diagnosis of posterior tibialis tendon tears and injuries, MR is an important tool in surgical planning. Often, MR is helpful for the diagnosis of peroneal tendon injury, including dislocations and peroneal splits, two entities that are seen to affect only the peroneal tendons. MR helps in the evaluation of avascular necrosis in any bone secondary to various systemic causes, particularly following talus fractures. MR has also been utilized to assess ankle sprains with complications, such as the ankle impingement syndrome, the sinus tarsi syndrome, and chronic instability, and to diagnose osteomyelitis (since the typical patient also has neuropathic disease bone, scintigraphy is invariably abnormal). MR is promising for the evaluation of reflex sympathetic dystrophy and is as useful for the evaluation of bone and soft tissue tumors as it is elsewhere in the skeleton. MR helps to characterize the biological aggressiveness of the tumor as well as its extent and therefore aids in surgical planning.