PMC8261161_01
Lateral radiograph of right ankle showing an os trigonum and posterior talus process fracture.
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fig1
The plain radiograph of the ankle demonstrated an os trigonum; however, due to the orientation of the medial tubercle, this was not clearly seen and he was incorrectly diagnosed as having os trigonum syndrome (see Figure 1).
Sagittal slice of T2 MRI of right ankle showing the posteromedial talus fracture fragment and associated oedema.
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fig2
The MRI scan reported mild inflammation associated with the os trigonum but also confirmed the presence of bone fragments posteromedially between FHL and the flexor digitorum longus (FDL) with marrow oedema affecting the medial tubercle of the talus (see Figure 2).
PMC8261161_02
Axial slice of T2 MRI of right ankle demonstrating fluid enhancement around the FHL tendon with the adjacent fractured posteromedial talus fragment.
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fig3
The fragment was between FDL and FHL tendons representing an "unusually located os trigonum," and there was also associated FHL tenosynovitis (see Figure 3).
Intraoperative image intensifier imaging demonstrating pre- (left) and post- (right) excision of the posteromedial talus fragment.
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fig4
He underwent operative intervention with an open excision of the bony fragment (see Figure 4).
PMC8261161_03
Lateral radiograph of right ankle demonstrating a prominent fractured and displaced posterior process of talus.
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fig5
His pain film radiograph demonstrated a prominent posterior process of the talus that was fractured and displaced, but this had been misdiagnosed as an os trigonum (see Figure 5).
Coronal slice of T2 MRI demonstrating the large os trigonum lateral to the FHL tendon and the fracture fragment medial to the FHL tendon.
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fig6
Interestingly, the MRI report did not describe the posteromedial tubercle fracture fragment that was the palpable mass (see Figure 6).
PMC8261161_04
Axial CT slice demonstrating lateral os trigonum and posteromedial talus fracture fragment nonunion.
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fig7
A right ankle CT scan demonstrated a malunion/partial union of the medial margin of the talus and secondary degenerative changes (see Figure 7).