Magnetic resonance imaging (MRI) of the ankle and hindfoot

While Magnetic Resonance Imaging (MRI) has become a routine diagnostic method to deal with pathology of the knee, little has been published about foot and ankle lesions. This is probably due to the anatomic complexity of bone and ligamentous structures of these small joints, necessitating the use of very thin slices from various orientation planes (orthogonal and oblique planes). A special technique is needed allowing a 3-dimensional (3D) analysis, using inframillimetric slices and more sophisticated equipment than for 2-dimensional (2D) MRI (high fields with good homogeneity, specialized image processors...). An initial potential indication of the method is the precise diagnosis of lateral ligamentous components in severe sprains. MRI may determine if surgical therapy is needed. The ligamentous components are reconstructed along their specific planes thanks to the 3D method. Furthermore, assessment of the ligamentous damage is also possible in chronic ankle instability (elongation, fibrotic appearance...). Thanks to the multiplanar approach, associated lesions of articular cartilage can be revealed in ankle sprains. The high sensitivity of MRI in slight modifications of medullary bone allows the early diagnosis of "occult" fractures (not seen on conventional radiographs), osteonecrosis, osteochondrosis and reflex sympathetic dystrophy syndrome. Finally, MRI easily displays all ankle and foot tendons and fascia and is particularly helpful in depicting partial tears and postoperative complications.