case_images: PMC8052159_01
case_images: Plain radiograph: (a) anteroposterior image and (b) lateral image. Computed tomography (CT): (c) axial image, (d) sagittal image, and (e) 3-dimensional image. The left ankle plain radiograph showed multiple oval free bodies at the anterior and posterior ankle joint space. CT image showed intra-articular multiple ossified oval mass lesions (yellow arrowhead), and some protrusions arose from the talus (yellow arrow).
case_images: CRIOR2021-5579684.001.jpg
case_images: PMC8052159_01_CRIOR2021-5579684.001.jpg
case_images: fig1
case_images: Left ankle plain radiography revealed multiple oval free bodies 10-15 mm in size at the anterior and posterior ankle joint spaces (Figures 1(a) and 1(b)). Computed tomography images showed intra-articular multiple ossified oval mass lesions and some protrusions arising from the talus (Figures 1(c)-1(e)).
case_images: Magnetic resonance (MR) image: (a) coronal T1-weighted image, (b) T2-weighted image, and (c) short T1 inversion recovery (STIR) image. T1- and T2-weighted MR images showed an intra-articular oval mass of a low intensity partially with high intensity and with high intensity on STIR image. The diffuse STIR high-intensity lesions were confirmed on the protuberance from the talus and the area underneath it.
case_images: CRIOR2021-5579684.002.jpg
case_images: PMC8052159_01_CRIOR2021-5579684.002.jpg
case_images: fig2
case_images: Diffuse STIR high-intensity lesions were confirmed on the protuberance from the talus and talar body underneath it, suggesting a bone marrow lesion of the protuberance and talus (Figure 2).
case_images: Intraoperative picture: (a) anterior midline incision, (b) posteromedial incision, (c) talar dome, and (d) removed intra-articular free bodies. Excisions of the protuberances from the talus rendered a circular articular cartilage defect (black arrow).
case_images: CRIOR2021-5579684.003.jpg
case_images: PMC8052159_01_CRIOR2021-5579684.003.jpg
case_images: fig3
case_images: With anterior midline and posteromedial incisions, intra-articular multiple mass lesions were removed (Figures 3(a) and 3(b)). The microfracture technique was performed for the cartilage defect (Figure 3(c)). On macroscopic examination, some mass lesions were colored brown, including the protuberance from the talus, while others were white (Figure 3(d)).
case_images: (a) Microscopic images of the synovium, (b) brown mass lesion, and (c) white mass lesion. No hyaline cartilage component was found in the synovium (a). The brown mass was trabecular bone covered by fibrous tissue (b). The white free bodies were thick cartilage cap with ossification, which resembled the epiphysis (c). Scale bar, 200 mum.
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case_images: PMC8052159_01_CRIOR2021-5579684.004.jpg
case_images: fig4
case_images: Microscopic examination revealed no hyaline cartilage component in the synovium (Figure 4(a)). The brown mass lesion was trabecular bone tissue covered almost exclusively by fibrous tissue, and only a small amount of cartilage was found (Figure 4(b)). The white mass lesions, all of which were loose bodies, were thick hyaline cartilage (cartilage cap) with central ossification, which resembled the epiphysis (Figure 4(c)).
case_images: Chronological ankle lateral plain radiograph. (a) Postoperative three months after primary surgery, (b) postoperative five months after primary surgery, (c) postoperative one year after primary surgery, and (d) postoperative six months after secondary surgery. (e) Arthroscopic findings during secondary surgery. Gradual growth of a new oval ossified free body in the posterior joint space of his left ankle after primary surgery (yellow arrow) (a-c). No recurrence after secondary surgery after six months postoperatively (d). The cartilage defect due to resection of the protuberance from the talus, which was treated with microfracture technique during primary operation, was covered with healthy cartilage (black arrow).
case_images: CRIOR2021-5579684.005.jpg
case_images: PMC8052159_01_CRIOR2021-5579684.005.jpg
case_images: fig5
case_images: Lateral plain radiography revealed the growth of a new oval ossified free body in the posterior joint space of his left ankle during postoperative follow-up (Figures 5(a)-5(c)). The cartilage defect, resulting from the resection of the protuberance from the talus, treated with microfracture in the primary operation was covered with healthy cartilage (Figure 5(e)). A recurrence of free body or protuberance was not confirmed by the plain radiographs during the postoperative follow-up of 6 months (Figure 5(d)).