Inner Ear Dysplasia
Joseph Junewick, MD FACR
over 7 years ago
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Fibrous tarsal coalition
Heather Borders, MD
|Diagnostic Category: Developmental or Congenital
|Created: over 7 years ago
|Updated: over 7 years ago
11 year old patient with ankle pain.
Fibrous coalition of the medial facet of the subtalar joint.
The medial facet of the subtalar joint is irregularly marginated and horizontally oriented with edema within the adjacent bone. There is no osseous bridging across the joint. The signal of the tissue in the joint was predominantly low on the sequences obtained. There is no talar beaking or significant degenerative change.
Coalition can be fibrous, osseous or cartilaginous. Most cases are congenital. Symptoms may not develop until osseous fusion begins. Approximately 50% are bilateral.
Radiograpic findings include the C-sign, anterior talar beaking, ball and socket ankle joint; for talocalcaneal coalition.
On CT, osseous coalition shows cortical continuity between affected bones. In non osseous coalition there may be joint space narrowing, irregularity, sclerosis and sometimes subchondral cysts. The orientation of the joint will also typically change and either be horizontally or inferiorly directed.
On MRI, osseous coalitions will again show marrow/osseous continuity. Edema will often be present. Fibrous or cartilaginous coalitions will show hypointensity on all imaging sequences and follow cartilage signal, respectively. These patiens are more likely to injure their peroneal tendons and these should be assessed.
J Herman Kan, Pediatric and Adolescent Musculoskeletal MRI. A case based approach.