Magnetic resonance imaging of ankle ligaments

The ankle is one of the most common sites of musculoskeletal injury. In a series of 1176 athletic injuries, 14% were found to be injuries of the ankle, and 85% of those were specifically sprains of ankle ligaments [1]. Although many ankle ligaments can be well assessed by an operator trained in ultrasound techniques, evaluation by magnetic resonance imaging (MRI) offers the advantages of a comprehensive and operator-independent examination [2]. In this article, a practical review of MRI of ankle ligaments is presented. The discussion is limited primarily to the ligaments surrounding the tibiotalar joint, particularly the inferior tibiofibular syndesmotic ligaments and the medial and lateral collateral ligaments (Table 1). Because of its close association with the deltoid ligament, the spring ligament is also included. Ligament names are represented by unambiguous abbreviations similar to those appearing in the literature [3-5]. For each ligament, normal anatomy, MRI appearance, and function will be addressed. Next, with regards to the injured ligament, basic mechanisms of injury will be reviewed, taking into consideration differing opinions in the literature that, in some cases, diverge from the classic teachings of Lauge and Hansen [3]. Because ligament injury usually manifests itself in similar ways, such as abnormal signal intensity (intrasubstance or periligamentous) or abnormal morphology (thickening, thinning, discontinuity, absence, irregularity, indistinctness, or heterotopic ossification) [2,4,6], additional imaging clues to injury that are ligamentspecific will be emphasized. Finally, because chronic injury is the leading cause of ankle impingement [7], we will cover those ankle impingement syndromes that are commonly caused by ligament injuries: anterolateral, anteromedial, posteromedial, and posterior (Figure 1). We omit anterior impingement, which is not directly caused by ligament injury; posterolateral impingement, which is not well described; and extra-articular syndromes [8,9]. (author)