case_images: PMC7364266_01
case_images: Preoperative photograph showing swelling of the posteromedial and posterolateral aspects (white arrows) of the right ankle.
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case_images: fig1
case_images: At the first visit to our department, physical examination revealed swelling and tenderness of the medial and lateral aspects of the ankle (Figure 1).
case_images: Lateral plain radiographic view of the right ankle obtained preoperatively showing several ossified masses in the posterior ankle area (arrow).
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case_images: fig2
case_images: A weight-bearing lateral plain radiographic view of the loose bodies in the posterior ankle extra-articular space is shown in Figure 2.
case_images: Computed tomography scans showing homogeneous calcifications with typical ring-and-arc chondroid mineralization in the posterior ankle (a) on a plain sagittal view (arrow) and (b) on a three-dimensional image view (arrow).
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case_images: fig3
case_images: Several loose bodies were seen on the ossified lesion in osteochondromatosis on computed tomography scans (Figures 3(a) and 3(b)).
case_images: Magnetic resonance imaging shows several small fusiform masses (arrow) surrounded by a fluid signal on T2-weighted (a) and short T1 inversion recovery (b) scans in the sagittal plane.
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case_images: PMC7364266_01_CRIOR2020-6580472.004.jpg
case_images: fig4
case_images: T1 inversion recovery images showed hypointense areas indicating loose bodies surrounded by effusion (Figures 4(a) and 4(b)). The preoperative diagnosis was osteochondromatosis of the posterior ankle extra-articular space, and a plan was made to reduce the patient's pain surgically using a minimally invasive arthroscopic approach.
case_images: Arthroscopic views of the posterior aspect of the right ankle. (a) A large loose body from the right posterior ankle extra-articular space (arrow) can be visualized. The arrowhead follows the superior-posterior aspect of the calcaneus. (b) Friction between a loose body (arrow) and the FHL tendon (arrowhead) can be seen. (c) A longitudinal tear and fibrillation were detected in the FHL tendon (arrow). FHL: flexor hallucis longus.
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case_images: PMC7364266_01_CRIOR2020-6580472.005.jpg
case_images: fig5
case_images: Several ossified loose bodies were then visualized at the posterior aspect of the talus in the posterior ankle space (Figure 5(a)). Loose bodies were impinging between the posterior aspect of the talus and calcaneus with friction between the loose bodies and the FHL tendon (Figure 5(b)). FHL tendon sheath could be visualized and the tendon was released with a shaver. Fibrillation and a friction-related longitudinal tear of the FHL were seen (Figure 5(c)) but could not be treated during posterior ankle arthroscopy.
case_images: Photograph showing the loose bodies that were endoscopically removed from the right posterior ankle extra-articular space.
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case_images: fig6
case_images: In total, four loose bodies were removed endoscopically from the right posterior ankle extra-articular space (Figure 6).
case_images: Histology slide showing peripheral chondrocytes.
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case_images: fig7
case_images: The histology report confirmed hypercellularity in the hyaline cartilage peripherally with no evidence of nuclear pleomorphism associated with binucleated or multinucleated lacunae, necrosis, or mitotic activity in the ossified lesion (Figure 7).
case_images: Lateral plain radiographic view of the right ankle showing no ossified loose bodies in the right posterior ankle extra-articular space.
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case_images: fig8
case_images: Plain radiographic and three-dimensional computed tomographic images showed no recurrence of the ossified masses (Figures 8 and 9).
case_images: Three-dimensional computed tomography scan obtained postoperatively shows no ossified lesions in the posterior ankle.
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case_images: fig9
case_images: Plain radiographic and three-dimensional computed tomographic images showed no recurrence of the ossified masses (Figures 8 and 9).