J. BEN HAFDHALLAH, S. BOURKHIS, F. SNENE, M.A.GHODHBANI, H. RAJHI, N. MNIF. CHARLE NICOLLE’S HOSPITAL, TUNIS, TUNISIA. MK6

OBJECTIVES Evaluate the role of imaging modalities in the diagnosis and management of the posterior tibio talian syndrome. It includes clinical situations secondary to entrapment of bony elements or soft tissue between the posterior edge of the tibia and calcaneus during plantar flexion of the ankle.

A CASE REPORT This is a 27-year-old male who usually complains of posterior ankle pain exacerbated by plantar flexion or dorsiflexion. An Achille tendinopathy was firstly suspected.

RESULTS  AN ULTRASOUND EXAM OF ACHILLE TENDON Tibio talian intra articular liquid Right anlke / axial plane

 Lateral ankle radiographs RESULTS Lateral ankle radiograph shows a prominent posterior process of the tibia and a long posterior talian process.

 MR imaging RESULTS Sagittal (T2 / T1-weighted) and axial (T1-weighted) MR image shows focal thickening of posterior pericapsular tissue ( ) but normal bone marrow signal intensity in the postérior process. Note the tibio talian intra articular liquid ( ).

 TREATMENT RESULTS A posterior tibio talian syndrome was diagnosed. The patient had an arthroscopic treatement with supression of prominent posterior process. Clinical evolution marked by an improvement. Lateral ankle radiograph before and after surgery shows a disappearance of prominent posterior process ( ).

DISCUSSION  Posterior impingement has been described under a variety of different names, including os trigonum syndrome and posterior tibiotalar compression syndrome.  The condition arises from compression of the soft tissues between the posterior process of the talus and the posterior tibia on plantar flexion of the ankle.

CAUSES The syndrome can develop after  a significant acute injury:  avulsion of the posterior talo-fibular ligament.  talar fracture.  disruption of an os trigonum.  A chronic injury:  a repetitive forced plantar flexion of the foot(ballet dancers). DISCUSSION

CLINICAL FEATURES  The syndrome usually manifests clinically when a significant soft-tissue component forms.  Clinical symptoms usually consist of posterior ankle pain exacerbated by plantar flexion or dorsiflexion.  Clinical examination shows:  Posterior tenderness anterior to and not involving the Achilles tendon.  Occasionally, palpable soft-tissue thickening DISCUSSION

CONVENTIONAL RADIOGRAPHS  Conventional radiographs may show a prominent lateral talar process or os trigonum. IMAGING FEATURES DISCUSSION

US exam  Ultrasound is a useful technique for accurate real-time guidance of therapeutic injection. IMAGING FEATURES DISCUSSION

 MR imaging  MR imaging shows:  Bone marrow edema.  A fracture line.  fluid in the synchondrosis.  Posterior capsular or ligament thickening with intermediate to low signal intensity on T2-weighted images. IMAGING FEATURES DISCUSSION

 The integrity of the ligaments.  Possible associated flexor hallucis longus abnormality or other internal derangement, which can alter any planned surgical approach.  Enhancement after intravenous administration of gadolinium contrast material can highlight small focal areas of synovitis.  MR imaging IMAGING FEATURES DISCUSSION

Management  Imaging-guided injection (a steroid or local anesthetic): Most cases of posterior impingement of the ankle respond to conservative treatment (physiotherapy).  Surgery: in resistant cases. IMAGING FEATURES DISCUSSION

CONCLUSION  Impingement syndromes of the ankle are usually a clinical diagnosis.  Conventional radiograph plays an important role in the initial assessment of these conditions.  MR imaging is most useful in posterior impingement, where it can identify the relative contributions of the osseous and soft-tissu components.