ANATOMIC AND MRI STUDY OF THE SUBTALAR LIGAMENTOUS SUPPORT

The diagnosis of subtalar instability remains difficult both clinicall y and radiographically. The authors present an anatomic and MRI study of the subtalar ligamentous support. The anatomic study has consisted in dissections and sections of cryoconserved hindfeet (15 cases) which precises the organisation of ligamentous bundles in the lateral (sinu s tarsi) and central (canalis tarsi) subtalar compartments, mainly rep resented by the trilayered inferior extensor retinaculum, the cervical talo-calcaneal ligament and the interosseous talo-calcaneal ligament. MRI study (1.5 tesla) of anatomic specimens was performed according t o defined types of sections: sagittal, coronal, coronal oblique, axial transverse. The correlations of anatomic and MRI sections allowed a p recise interpretation of the subtalar ligamentous support as anatomica lly described. A complementary clinical MRI study was performed which allowed the validation of ''the inversion test'': this test optimizes the visualization of the different ligamentous structures. Relative to the difficulties of conventional imaging procedures, MRI appears of c linical relevance in the diagnosis of subtalar instabilities. This tec hnique allows direct visualization of ligaments (or their rupture) and therefore a better evaluation of subtalar involvement in ankle sprain . This paper present a functional concept in MRI articular Ligamentous restraints concern.