How To Diagnose Lateral Ankle Injuries

By Remy Ardizzone, DPM, and Ronald L. Valmassy, DPM

What You Should Know About Intraarticular Injuries

   In the lateral ankle, intraarticular injuries typically consist of impingement syndromes, chondral and osteochondral lesions. Chondral lesions involve only the articular cartilage while osteochondral lesions consist of injury to the cartilage and the underlying bone.42 Occasionally, a talar dome lesion may be visible on initial X-ray following an inversion injury or a patient may have a loose body present from a prior injury that appears on a X-ray. However, these injuries frequently do not manifest until later in the healing process or once the patient returns to regular activity.    Chronic ankle instability has a higher incidence of osteochondral lesions than acute distal fibular fracture.43 The patient may complain of periodic “clicking,” “popping” or “locking” of the ankle. Frequently, these occurrences are random. There may be persistent pain to the anterolateral ankle that often occurs with end-range dorsiflexion, especially with impact activities or walking uphill. Patients often describe the pain as a dull, aching sensation about the ankle joint.3,44    Chondral and osteochondral lesions typically involve the posterior medial and anterior lateral aspects of the talus.45,46 Posterior medial lesions frequently are less symptomatic and not always associated with trauma. Anterior lateral lesions are associated with trauma in nearly 100 percent of cases.44-47 One should maintain a high index of suspicion in patients who have persistent pain despite normal radiographs or those who fail to improve after traditional treatment following a routine ankle sprain.    Physical examination may reveal persistent focal swelling to the anterior lateral ankle with pain to palpation of this area, particularly with the ankle in plantarflexion. Crepitus may be present and pain may increase with tibial talar compression. The presence of an intraarticular loose body may precipitate locking. In late stages, the presentation will be consistent with an arthritic joint.    Although some osteochondral lesions may be visible on plain radiographs, which provide the basis for the Berndt-Hardy classification, a MRI provides more specific evidence of pathology.45 Various sequences highlight different tissues, contrast and spatial resolution. Fat-suppressed proton density-weighted or T2-weighted sequences (STIRs) are often the most sensitive for detecting contusion or trabecular injury to the underlying bone.3 Bone marrow edema adjacent to chondral defect generally indicates that the lesion is active or likely symptomatic. One may use MRI to help assess and track healing of lesions over time.    Impingement syndromes generally result from hyalinized fibriolysis of the hemarthrosis associated with lateral ankle ligament injury, leading to posttraumatic synovitis within the anterolateral gutter.48,49 This inflamed scar tissue, which may be triangular or meniscoid in shape, impinges on the anterolateral margin of the talar dome, causing pain and decreased range of motion.20,50 Over time, this may cause repetitive abrasion of the chondral surface and erosion of the articular cartilage.    In impingement syndromes, the clinical examination may reveal chronic edema to the anterolateral ankle in the location of the anterior talofibular ligament. There is pain to palpation in this region or one may only produce pain with provocation such as closed chain dorsiflexion of the ankle. There may be resistance to attempted rotary motion of the ankle as well as decreased ankle joint dorsiflexion compared to the contralateral side.    Plain X-rays may reveal the presence of an osseus intraarticular loose body. Whether this is present or not, obtaining a MRI will help determine the location of the loose body and can also detect excessive scar tissue or meniscoid bodies that may be limiting joint motion and contributing to persistent painful synovitis.3

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