Exercise-induced metacarpophalangeal joint adaptation in the Thoroughbred racehorse.
- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
The research article examines the impact of exercise on the metacarpophalangeal joint of Thoroughbred racehorses, and the differences in joint stress outcomes between athletic and non-athletic horses. The researchers concluded that an accumulation of microdamage and stress in the joints of athletic horses significantly exceeded that of non-athletic horses.
Research Methodology
A comparative analysis was conducted on two groups of horses:
- young Thoroughbred racehorses that were actively racing (10 horses)
- non-athletic horses (8 horses)
The study employed histologic examination of the distal end of the third metacarpal bone in the horses’ joints. Morphometric measurements were taken from five regions of the joint surface. The researchers measured a variety of indicators of joint stress, including hyaline cartilage width, microcrack density, blood vessel density, bone volume fraction, and osteocyte density.
Findings and Observations
The study found that the adaptation of articular cartilage was similar in both groups of horses. Interestingly, the non-athletic horses showed increased vascularization of articular cartilage. Microcracks in the joint surface were co-localized with blood vessels and resorption spaces. These microcracks were more prevalent in the condylar grooves of the athletic horses compared to the other joint regions as well as the non-athletic horses.
Joint Stress Outcomes
Microcracks often led to the development of intracortical articular condylar stress fractures in some joints. There was targeted remodeling of the affected subchondral plate. Additionally, the subchondral plate of the condyles in the athletic horses had an atypically stained bone matrix with increased numbers of osteocytes showing abnormal characteristics. However, there were not significant differences in the number of osteocytes between the athletic and non-athletic horses.
Conclusion
The researchers concluded that there were significantly greater differences in site-specific microdamage accumulation and remodeling between athletic and non-athletic horses than differences in osteocyte morphology. However, the presence of an abnormal subchondral bone matrix in the athletic horses was associated with extensive osteocyte loss. While osteocyte mechanotransduction is considered crucial for functional adaptation, it is likely that multiple mechanotransduction pathways regulate adaptation in this model.
Cite This Article
Publication
Researcher Affiliations
- Comparative Orthopaedic Research Laboratory, School of Veterinary Medicine, University of Wisconsin-Madison, 53706, USA. muirp@svm.vetmed.wisc.edu
MeSH Terms
- Adaptation, Physiological
- Animals
- Bone Remodeling
- Breeding
- Calcinosis / pathology
- Cartilage, Articular / blood supply
- Cartilage, Articular / pathology
- Fractures, Bone / pathology
- Fractures, Stress / pathology
- Horse Diseases / etiology
- Horse Diseases / pathology
- Horses
- Metacarpophalangeal Joint / blood supply
- Metacarpophalangeal Joint / injuries
- Metacarpophalangeal Joint / pathology
- Metacarpus / blood supply
- Metacarpus / pathology
- Microscopy, Confocal
- Osteocytes / pathology
- Physical Conditioning, Animal / adverse effects
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