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Case Reports
. 2017;28(3):123-126.
doi: 10.1294/jes.28.123. Epub 2017 Sep 20.

Histopathological Findings of Apical Fracture of the Proximal Sesamoid Bones in Young Thoroughbred Foals

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Free PMC article
Case Reports

Histopathological Findings of Apical Fracture of the Proximal Sesamoid Bones in Young Thoroughbred Foals

Fumio Sato et al. J Equine Sci. .
Free PMC article

Abstract

Although radiographic findings at the apical portion of the proximal sesamoid bone (PSB) are often observed in young Thoroughbred foals, conflicting findings, either fractures or apparent secondary ossifications centers, have been reported. Three cases (aged 2, 5, and 7 weeks) were identified in 30 necropsied foals (0-31 weeks old). Histopathologically, the subchondral trabecular woven bone was fractured and exhibited focal necrosis of woven bone, fibrin exudate, and/or fibrosis within the foci. In the 7-week-old case, proliferations of chondrocytes were also observed. These findings suggest that the radiographic findings represented a healing process of the apical PSB fractures associated with the mechanically damaged subchondral trabeculae. Developmental PSB injuries should be taken into consideration during the management of young Thoroughbred foals.

Keywords: foal; proximal sesamoid bone fracture; subchondral lesion.

Figures

Fig. 1.
Fig. 1.
Latero-medial radiographs of cases with radiographic findings in the apical part (arrows) of the PSBs. Left forelimb of Case 1 (A); left and right forelimbs of Case 2 (B and C); and left forelimb of Case 3 (D). Arrows indicate the parts of the radiographic findings in the apical portion of the PSBs.
Fig. 2.
Fig. 2.
Macrographs of the medial PSB of the left forelimb of Case 1 (A), lateral PSB of the left and right forelimbs of Case 2 (E, I), and medial and lateral PSBs of the left forelimb of Case 3 (M and Q), corresponding hematoxylin and eosin staining micrographs (B, F, J, N, Q), and high-magnification views of the areas enclosed by dashed line squares (C, G, K, O, S and D, H, L, P, T). Arrows indicate the positions of the radiographic findings. Bar=5.0 mm (black), 0.5 mm (blue) and 100 µm (red).

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