Age / Sex : 18 / M

Chief complaint : Chronic heel pain, limitation of motion

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy of Sheen-Woo Lee, Gil Hospital, Gachon University College of Medicine

Discussion

Answer:  Extrarticular talocalcaneal coalition

Findings: Irregular narrowing of posteromedial talocalcaneal joint space, immediately posterior to sustentaculum.

         Broadening of posterior margin of sustentaculum tali and posteromedial talar process

         Low SI of joint space on T1WI, T2WI.

         Osseous edema across the coalition

         Osseous protrusion into tarsal tunnel

Differential Diagnosis: Medial talocalcaneal ligament

Discussion:

 Tarsal coalition is defined as abnormal bridging between tarsal bones. It can be osseous, cartilaginous or fibrous. Radiograph and CT may show bone bridging, proliferation or irregularity of the bony margins at the level of coalition. MR is useful for determining the type of coalition. Osseous subtalar coalitions demonstrate bone marrow signal continuing across the fused articulation, cartilaginous type generally demonstrate signal intensity similar to fluid or cartilage extending across the abnormal joint, and fibrous type demonstrate low-signal intensity on all sequences across the affected joint space. Non-osseous subtalar coalitions create abnormal mechanical stress across the affected joint with resultant bone marrow edema adjacent to the articulation.

References:

1) Diagnostic Imaging, Musculoskeletal, Nontraumatic disease, Manaster et al

 2) 근골격 영상의학, 강흥식 외

 3) Lawrence DA. et al. Tarsal Coalitions: Radiographic, CT, and MR Imaging Findings. HSSJ (2014) 10:153–166.