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Subchondral bone failure in overload arthrosis: a scanning electron microscopic study in horses.
J Musculoskelet Neuronal Interact. 2006 Jul-Sep; 6(3):251-7.JM

Abstract

Mechanical overload leads to a common arthrosis in the metacarpal condyle of the fetlock joint of racehorses. This is usually asymptomatic but severe forms can cause lameness. Subchondral bone failure is often present and the predictability of the site provided an opportunity to study of the progression of bone failure from microcracks to actual collapse of subchondral bone. Twenty-five fetlock condyles from racehorses with various stages of disease were selected. Stages ranged from mild through severe subchondral bone sclerosis, to the collapse of bone and indentation or loss of cartilage known as 'traumatic osteochondrosis'. Parasagittal slices were radiographed and examined with scanning electron microscopy. Fine matrix cracks were seen in the subchondral bone layer above the calcified cartilage and suggested loss of water or other non-collagenous components. The earliest microcracks appeared to develop in the sclerotic bone within 1-3 mm of the calcified cartilage layer and extend parallel to it in irregular branching lines. Longer cracks or microfractures appeared to develop gaps as fragmentation occurred along the margins. Occasional osteoclastic resorption sites along the fracture lines indicated activated remodeling may have caused previous weakening. In one sample, smoothly ground fragments were found in a fracture gap. Bone collapse occurred when there was compaction of the fragmented matrix along the microfracture. Bone collapse and fracture lines through the calcified cartilage were associated with indentation of articular cartilage at the site.

Authors+Show Affiliations

Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA. rnorrdin@colostate.eduNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17142946

Citation

Norrdin, R W., and S M. Stover. "Subchondral Bone Failure in Overload Arthrosis: a Scanning Electron Microscopic Study in Horses." Journal of Musculoskeletal & Neuronal Interactions, vol. 6, no. 3, 2006, pp. 251-7.
Norrdin RW, Stover SM. Subchondral bone failure in overload arthrosis: a scanning electron microscopic study in horses. J Musculoskelet Neuronal Interact. 2006;6(3):251-7.
Norrdin, R. W., & Stover, S. M. (2006). Subchondral bone failure in overload arthrosis: a scanning electron microscopic study in horses. Journal of Musculoskeletal & Neuronal Interactions, 6(3), 251-7.
Norrdin RW, Stover SM. Subchondral Bone Failure in Overload Arthrosis: a Scanning Electron Microscopic Study in Horses. J Musculoskelet Neuronal Interact. 2006 Jul-Sep;6(3):251-7. PubMed PMID: 17142946.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Subchondral bone failure in overload arthrosis: a scanning electron microscopic study in horses. AU - Norrdin,R W, AU - Stover,S M, PY - 2006/12/5/pubmed PY - 2007/1/18/medline PY - 2006/12/5/entrez SP - 251 EP - 7 JF - Journal of musculoskeletal & neuronal interactions JO - J Musculoskelet Neuronal Interact VL - 6 IS - 3 N2 - Mechanical overload leads to a common arthrosis in the metacarpal condyle of the fetlock joint of racehorses. This is usually asymptomatic but severe forms can cause lameness. Subchondral bone failure is often present and the predictability of the site provided an opportunity to study of the progression of bone failure from microcracks to actual collapse of subchondral bone. Twenty-five fetlock condyles from racehorses with various stages of disease were selected. Stages ranged from mild through severe subchondral bone sclerosis, to the collapse of bone and indentation or loss of cartilage known as 'traumatic osteochondrosis'. Parasagittal slices were radiographed and examined with scanning electron microscopy. Fine matrix cracks were seen in the subchondral bone layer above the calcified cartilage and suggested loss of water or other non-collagenous components. The earliest microcracks appeared to develop in the sclerotic bone within 1-3 mm of the calcified cartilage layer and extend parallel to it in irregular branching lines. Longer cracks or microfractures appeared to develop gaps as fragmentation occurred along the margins. Occasional osteoclastic resorption sites along the fracture lines indicated activated remodeling may have caused previous weakening. In one sample, smoothly ground fragments were found in a fracture gap. Bone collapse occurred when there was compaction of the fragmented matrix along the microfracture. Bone collapse and fracture lines through the calcified cartilage were associated with indentation of articular cartilage at the site. SN - 1108-7161 UR - https://www.unboundmedicine.com/medline/citation/17142946/Subchondral_bone_failure_in_overload_arthrosis:_a_scanning_electron_microscopic_study_in_horses_ L2 - http://www.ismni.org/jmni/pdf/25/07NORRDIN.pdf DB - PRIME DP - Unbound Medicine ER -