TY - JOUR
T1 - Osteoclast density is not increased in bone adjacent to radiolucencies (cysts) in juvenile equine medial femoral condyles
AU - Fortin-Trahan, Rosalie
AU - Lemirre, Thibaut
AU - Santschi, Elizabeth M.
AU - Janes, Jennifer G
AU - Richard, Hélène
AU - Fogarty, Ursula
AU - Beauchamp, Guy
AU - Girard, Christiane A.
AU - Laverty, Sheila
N1 - Publisher Copyright:
© 2021 EVJ Ltd.
PY - 2022/9
Y1 - 2022/9
N2 - Background: There is a knowledge gap about how equine MFC subchondral radiolucencies (SR) arise and evolve. Osteoclasts are believed to have a role but have not been studied in situ. Objectives: To measure and compare osteoclast density and the percentage of chondroclasts in healthy and MFC SR specimens from juvenile Thoroughbreds. Study design: Cadaveric study. Methods: Medial femoral condyles (MFC) from a tissue bank of equine stifles were studied. Inclusion criteria were MFCs (≤8 months old) with a computed tomography SR lesion and histological focal failure of endochondral ossification (L group). Contralateral, lesion-free, MFCs were a control group (CC). Osteochondral slabs were cut through the lesion (L), a healthy site immediately caudal to the lesion, (internal control; IC) and the contralateral, site-matched controls (CC). Histological sections were immunostained with Cathepsin K for osteoclast counting. Osteoclasts in contact with the growth cartilage (chondroclasts) were also counted. The sections were segmented into regions of interest (ROI) at different depths in the subchondral bone: ROI1 (0-1 mm), ROI2 (1-3 mm) and ROI3 (3-6 mm). Osteoclasts were counted and the bone area was measured in each ROI to calculate their density. Chondroclasts were counted in ROI1. Results: Sections were studied from L and IC (n = 6) and CC sites (n = 5). Osteoclast density was significantly higher in ROI1 when compared with ROI3 in all groups. Although higher osteoclast density was measured in ROI1 in the L group, no significant differences were detected when compared with control ROIs. The proportion of chondroclasts in ROI1 was lower in the L sections when compared with controls but no significant differences were detected. Main limitations: Limited sample size. Conclusions: Osteoclasts are important actors in MFC subchondral bone development, digesting both growth cartilage (chondroclasts) and bone, but the pathophysiology of early MFC SRs cannot be explained solely by an increased osteoclast presence in the subchondral bone.
AB - Background: There is a knowledge gap about how equine MFC subchondral radiolucencies (SR) arise and evolve. Osteoclasts are believed to have a role but have not been studied in situ. Objectives: To measure and compare osteoclast density and the percentage of chondroclasts in healthy and MFC SR specimens from juvenile Thoroughbreds. Study design: Cadaveric study. Methods: Medial femoral condyles (MFC) from a tissue bank of equine stifles were studied. Inclusion criteria were MFCs (≤8 months old) with a computed tomography SR lesion and histological focal failure of endochondral ossification (L group). Contralateral, lesion-free, MFCs were a control group (CC). Osteochondral slabs were cut through the lesion (L), a healthy site immediately caudal to the lesion, (internal control; IC) and the contralateral, site-matched controls (CC). Histological sections were immunostained with Cathepsin K for osteoclast counting. Osteoclasts in contact with the growth cartilage (chondroclasts) were also counted. The sections were segmented into regions of interest (ROI) at different depths in the subchondral bone: ROI1 (0-1 mm), ROI2 (1-3 mm) and ROI3 (3-6 mm). Osteoclasts were counted and the bone area was measured in each ROI to calculate their density. Chondroclasts were counted in ROI1. Results: Sections were studied from L and IC (n = 6) and CC sites (n = 5). Osteoclast density was significantly higher in ROI1 when compared with ROI3 in all groups. Although higher osteoclast density was measured in ROI1 in the L group, no significant differences were detected when compared with control ROIs. The proportion of chondroclasts in ROI1 was lower in the L sections when compared with controls but no significant differences were detected. Main limitations: Limited sample size. Conclusions: Osteoclasts are important actors in MFC subchondral bone development, digesting both growth cartilage (chondroclasts) and bone, but the pathophysiology of early MFC SRs cannot be explained solely by an increased osteoclast presence in the subchondral bone.
KW - Cathepsin K
KW - chondroclast
KW - cyst
KW - horse
KW - medial femoral condyle
KW - osteoclast
KW - subchondral radiolucency
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U2 - 10.1111/evj.13530
DO - 10.1111/evj.13530
M3 - Article
C2 - 34716940
AN - SCOPUS:85119205351
SN - 0425-1644
VL - 54
SP - 989
EP - 998
JO - Equine Veterinary Journal
JF - Equine Veterinary Journal
IS - 5
ER -