Conventional MRI Versus MR Arthrography in Evaluation of Ankle Impingement Syndromes and Intra Articular Pathologies.

Overview

Chronic ankle pain is a common clinical problem with a wide differential diagnosis. Soft-tissue and osseous impingement syndromes are now increasingly recognized as a significant cause of chronic ankle pain. Ankle impingement syndromes are defined as pathologic conditions resulting in chronic, painful restriction to movement at the tibiotalar articulation secondary to soft-tissue or osseous abnormalities. Ankle impingement is classified according to its anatomic relationship to the tibiotalar joint as anterolateral, anterior, anteromedial, posteromedial, or posterior impingement.

The anterolateral impingement syndrome is caused by obstruction of the so-called anterolateral gutter (ALG) or recess secondary to an inversion injury resulting in disruption of the syndesmotic and/or lateral collateral ligaments and capsule. In anterior impingement,Arthroscopic evaluations suggest direct microtrauma to the talus and tibia as the aetiology. The natural course of this microtraumas to form osseous spurs. In anteromedial impingement,The mechanism is not well understood but is likely a rare complication of a supination (inversion) injury rather than a pronation (eversion) injury as initially hypothesized.During the acute injury, there is damage to the anterior tibiotalar ligament, which subsequently thickens. In addition toligament thickening, osteophytes, synovitis and fractures have been described as other possible causative factors. In posteromedial impingement, the common precipitating injury for posteromedial ankle impingement is a plantar flexion, inversion and internal rotation trauma. This can lead to damage to the PTTL and associated synovitis. The majority of the posterior impingement syndromes are related to the posterior talus.The secondary ossification centre of the posterolateral talus forms around 8-13 years of age and then subsequently fuses within 1 year of that. Occasionally (approximately 7%), there may be non-fusion with a resultant ostrigonum. Conventional MR imaging can accurately detect and localize osteophytes and associated lesions. In addition, MR imaging provides an easy evaluation of any articular cartilage changes, ligamentous injury, and occult bony contusions. Direct magnetic resonance (MR) arthrography extends the capabilities of conventional MR imaging and utilizes the natural advantages gained from joint effusion. Contrast solution distends the joint capsule, outlines intra articular structures,and leaks into abnormalities.It can detect cartilage damage, intra articular loose bodies and osteochondral talar lesions.