Femoral epiphyseal cartilage matrix changes at predilection sites of equine osteochondrosis: Quantitative MRI, second-harmonic microscopy, and histological findings.
Abstract: Osteochondrosis is an ischemic chondronecrosis of epiphyseal growth cartilage that results in focal failure of endochondral ossification and osteochondritis dissecans at specific sites in the epiphyses of humans and animals, including horses. The upstream events leading to the focal ischemia remain unknown. The epiphyseal growth cartilage matrix is composed of proteoglycan and collagen macromolecules and encases its vascular tree in canals. The matrix undergoes major dynamic changes in early life that could weaken it biomechanically and predispose it to focal trauma and vascular failure. Subregions in neonatal foal femoral epiphyses (n = 10 osteochondrosis predisposed; n = 6 control) were assessed for proteoglycan and collagen structure/content employing 3T quantitative MRI (3T qMRI: T1ρ and T2 maps). Site-matched validations were made with histology, immunohistochemistry, and second-harmonic microscopy. Growth cartilage T1ρ and T2 relaxation times were significantly increased (p < 0.002) within the proximal third of the trochlea, a site predisposed to osteochondrosis, when compared with other regions. However, this was observed in both control and osteochondrosis predisposed specimens. Microscopic evaluation of this region revealed an expansive area with low proteoglycan content and a hypertrophic-like appearance on second-harmonic microscopy. We speculate that this matrix structure and composition, though physiological, may weaken the epiphyseal growth cartilage biomechanically in focal regions and could enhance the risk of vascular failure with trauma leading to osteochondrosis. However, additional investigations are now required to confirm this. 3T qMRI will be useful for future non-invasive longitudinal studies to track the osteochondrosis disease trajectory in animals and humans. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1743-1752, 2016.
© 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
Publication Date: 2016-02-08 PubMed ID: 27734566DOI: 10.1002/jor.23176Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the changes in cartilage matrix in horses that may make them susceptible to osteochondrosis, a disorder that affects growth cartilage. Advanced technologies such as magnetic resonance imaging (MRI), histology, immunohistochemistry, and second-harmonic microscopy were used for this purpose.
Study Context and Aim
- Osteochondrosis is a condition affecting the growth cartilage in humans and animals. It’s an ischemic chondronecrosis that results in a localized failure of endochondral ossification or osteochondritis dissecans.
- Despite extensive study, the exact causes that lead to localised ischemia in this condition remain unknown.
- The goal of this study was to uncover the precursory events that lead to this focal ischemia, focusing specifically on the early-life dynamic changes in the cartilage matrix that may predispose it to biomechanical weakness and subsequent vascular failure.
Methodology
- The researchers examined the femoral epiphyses (end part of a long bone) in neonatal foal —equine species— (10 osteochondrosis gifted and 6 controlled)
- The cartilage structure and content of proteoglycan and collagen—a primary constituent of cartilage—was studied with 3T qMRI: T1ρ and T2 maps.
- Second-harmonic microscopy, histology, and immunohistochemistry were used to validate the findings made in the aforementioned sites.
Results and Interpretation
- Findings indicated that there were significantly increased T1ρ and T2 relaxation times in growth cartilage within the proximal third of the trochlea – a site predisposed to osteochondrosis, as compared to other regions.
- This observation was made in control samples as well as osteochondrosis-predisposed specimens, implying that such a condition might be physiological, but not exclusive to osteochondrosis cases.
- Upon microscopic examination, areas with low proteoglycan content and hypertrophic-like appearance were revealed. This indicates that the matrix structure and composition may be weakening the growth cartilage in some areas, possibly enhancing the risk of vascular failure following trauma, which could lead to osteochondrosis.
Implications and Future Research Directions
- This research hasn’t definitively concluded that the observed changes in matrix composition and structure lead to osteochondrosis, and future investigations are needed to confirm these findings.
- The results suggest that the 3T qMRI might be a valuable tool for non-invasive longitudinal studies investigating the disease trajectory of osteochondrosis in animals and humans.
Cite This Article
APA
Martel G, Couture CA, Gilbert G, Bancelin S, Richard H, Moser T, Kiss S, Légaré F, Laverty S.
(2016).
Femoral epiphyseal cartilage matrix changes at predilection sites of equine osteochondrosis: Quantitative MRI, second-harmonic microscopy, and histological findings.
J Orthop Res, 34(10), 1743-1752.
https://doi.org/10.1002/jor.23176 Publication
Researcher Affiliations
- Comparative Orthopaedic Research Laboratory, Faculté de médecine vétérinaire, Université de Montréal, Québec, Canada.
- INRS-EMT, Université du Québec, Québec, Canada.
- MR Clinical Science, Philips Healthcare, Markham, Ontario, Canada.
- INRS-EMT, Université du Québec, Québec, Canada.
- Comparative Orthopaedic Research Laboratory, Faculté de médecine vétérinaire, Université de Montréal, Québec, Canada.
- Department of Radiology, Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Québec, Canada.
- Department of Radiology, Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Québec, Canada.
- INRS-EMT, Université du Québec, Québec, Canada.
- Comparative Orthopaedic Research Laboratory, Faculté de médecine vétérinaire, Université de Montréal, Québec, Canada. sheila.laverty@umontreal.ca.
MeSH Terms
- Animals
- Collagen Type II / metabolism
- Female
- Femur
- Growth Plate / metabolism
- Growth Plate / pathology
- Horses
- Magnetic Resonance Imaging
- Male
- Osteochondrosis / etiology
- Osteochondrosis / metabolism
- Osteochondrosis / pathology
- Proteoglycans / metabolism
Citations
This article has been cited 2 times.- Lemirre T, Santschi E, Girard C, Fogarty U, Chapuis L, Richard H, Beauchamp G, Laverty S. Maturation of the equine medial femoral condyle osteochondral unit.. Osteoarthr Cartil Open 2020 Mar;2(1):100029.
- Finnøy A, Olstad K, Lilledahl MB. Non-linear optical microscopy of cartilage canals in the distal femur of young pigs may reveal the cause of articular osteochondrosis.. BMC Vet Res 2017 Aug 22;13(1):270.
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