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.
|Number of pages||10|
|Journal||Equine Veterinary Journal|
|State||Published - Sep 2022|
Bibliographical noteFunding Information:
This study was supported by grants from Fonds en santé équine de la Faculté de médecine vétérinaire de l’Université de Montréal and Zoetis. Sheila Laverty's laboratory is currently funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) and by the Quebec Cell, Tissue and Gene Therapy Network –ThéCell (a thematic network supported by the Fonds de recherche du Québec–Santé). We remain grateful for Dr John Mort's (RIP) gift of Cathepsin K antibodies to our laboratory. We would also like to extend our thanks to the technical staff at the University of Kentucky and Kansas State University for their assistance with sample collection.
This study was supported by grants from Fonds en santé équine de la Faculté de médecine vétérinaire de l’Université de Montréal and Zoetis. Sheila Laverty's laboratory is currently funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) and by the Quebec Cell, Tissue and Gene Therapy Network –ThéCell (a thematic network supported by the Fonds de recherche du Québec–Santé).
© 2021 EVJ Ltd.
- Cathepsin K
- medial femoral condyle
- subchondral radiolucency
ASJC Scopus subject areas