Sagittal T1 MR in a pre-teen with ankle pain shows elongatio | Figure 1

CincyKidsRad

Cincinnati Children's Radiology

Sagittal T1 MR in a pre-teen with ankle pain shows elongation, irregularity, and low signal intensity of the anterior process of the calcaneus and the adjacent navicular. However, no osseous continuity is seen. These findings are typical of a fibrocartilaginous calcaneonavicular coalition. This tarsal coalition can be suggested on lateral foot radiographs by an elongated calcaneal anterior process but is best visualized with an oblique foot radiograph. Conservative therapy may be tried initially, but resection of the coalition is often performed for definitive treatment. #MSKMonday

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AP x-ray of the foot and lateral x-ray of the ankle shows coalition (arrow) of the medial cuneiform and the navicular bone. A coalition is an abnormal bridging of the bones. It is usually congenital. The most common site of a coalition in the feet is either between the calcaneus and the navicular or between the calcaneus and the talus. #MSKMonday


Oblique radiographs of the left foot (image 1 and zoomed-in focusing on the area of abnormality on image 2) show a calcaneonavicular coalition (arrow). Calcaneonavicular coalition is often best seen on the oblique image. An ossific bar connects the anterior process of the calcaneus to the lateral navicular. The coalition can be fibrous or bony. If symptomatic, the coalition can be resected (image 3).


Lateral radiograph of the ankle shows the continuous C sign (image 2) of a talocalcaneal coalition (arrow on image 3). Coalitions of the foot most commonly occur between the talus and calcaneus or the calcaneus and the navicular. While most patients with a talocalcaneal coalition are asymptomatic, some patients can present with repeated ankle sprains and pain present with pain at the site of coalition distal to the medial malleolus. The pain is aggravated by running, jumping, or prolonged standing. #MSKMonday #MusculoskeletalMonday


When looking at image 6, note four tendons in the medial flexor compartment. This is known as "the sign of too many tendons". The arrows in image 6 point to a complex longitudinal split tear of the posterior tibialis. This is also visualized on image 7 (arrow). Abnormal longitudinal high-grade partial split tear is shown on images 8 and 9 (arrows). In the setting of tendinosis and split tears, it is useful to identify the proximal-distal length of the tear. In this case, retromalleolar, inframalleolar, and postmalleolar segments are swollen and abnormal as the posterior tibialis courses behind the medial malleolus into the arch of the foot and navicular attachments. Periarticular arthropathic spurring is identified within the midfoot, sagittally. Additionally, note unrelated prominent medial process of the navicular, which has close approximation to the anterior calcaneal process outlined on image 10 (arrows). This resembles fibrous coalition; however, no osseous edema. No bony bridging is noted. The navicular is simply dysplastic.