Does periosteal scraping of the third metacarpal bone reduce the incidence of ‘bucked shins’ in young Thoroughbred racehorses?

Objectives The exact aetiology and pathogenesis of microdamage-induced long bone fractures remain unknown. These fractures are likely to be the result of inadequate bone remodelling in response to damage. This study aims to identify an association of osteocyte apoptosis, the presence of osteocytic osteolysis, and any alterations in sclerostin expression with a fracture of the third metacarpal (Mc-III) bone of Thoroughbred racehorses. Methods A total of 30 Mc-III bones were obtained; ten bones were fractured during racing, ten were from the contralateral limb, and ten were from control horses. Each Mc-III bone was divided into a fracture site, condyle, condylar groove, and sagittal ridge. Microcracks and diffuse microdamage were quantified. Apoptotic osteocytes were measured using TUNEL staining. Cathepsin K, matrix metalloproteinase-13 (MMP-13), HtrA1, and sclerostin expression were analyzed. Results In the fracture group, microdamage was elevated 38.9% (sd 2.6) compared with controls. There was no difference in the osteocyte number and the percentage of apoptotic cells between contralateral limb and unraced control; however, there were significantly fewer apoptotic cells in fractured samples (p < 0.02). Immunohistochemistry showed that in deep zones of the fractured samples, sclerostin expression was significantly higher (p < 0.03) than the total number of osteocytes. No increase in cathepsin K, MMP-13, or HtrA1 was present. Conclusion There is increased microdamage in Mc-III bones that have fractured during racing. In this study, this is not associated with osteocyte apoptosis or osteocytic osteolysis. The finding of increased sclerostin in the region of the fracture suggests that this protein may be playing a key role in the regulation of bone microdamage during stress adaptation. Cite this article: N. Hopper, E. Singer, F. Henson. Increased sclerostin associated with stress fracture of the third metacarpal bone in the Thoroughbred racehorse. Bone Joint Res 2018;7:94–102. DOI: 10.1302/2046-3758.71.BJR-2016-0202.R4.

Download Full-text

Relationships of exercise regimen and racetrack surface to modeling/remodeling of the third metacarpal bone in two year-old Thoroughbred racehorses

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0038-1632738 ◽

2002 ◽

Vol 15 (04) ◽

pp. 195-199 ◽

Cited By ~ 12

Author(s):

D. M. Nunamaker

Keyword(s):

Cross Sections ◽

Dorsal Surface ◽

Metacarpal Bone ◽

Control Group ◽

Bone Modeling ◽

Cross Sectional ◽

The Third ◽

Thoroughbred Racehorses ◽

The Cross ◽

The Individual

SummaryThe effects of two different training regimens, two different racetrack surfaces (dirt and woodchip), as well as no training (control) were studied to determine their relationships to bone modeling/remodeling and cross-sectional inertial properties in the third metacarpal bone (Mclll) of the young Thoroughbred racehorse. Eight two-year old Thoroughbred racehorses were divided into four groups and subjected to different training regimens over a period of five months. At the end of the training period 100 micron cross sections of Mclll were examined using microradiography and the cross-sectional inertial properties of MCI 11 were determined. The results showed striking differences in the appearance of the bone cross sections with most of the bone modeling occurring on the dorso- medial surface of the ‘classically’ exercised animals and bone deposition on the dorsal surface in the ‘Modified-Classical’ training groups. Inertial properties were different between the groups with the ‘Classically’ trained animals having Imin values similar to the control group while the ‘Modified-Classically’ trained group had large increases in Imin at the mid diaphysis similar to reported measurements of older racehorses. These areal measurements of the cross sections, indicating resistance to bending in the dorsal palmar direction, showed the effects of training on the individual groups.

Download Full-text

Articular calcified cartilage canals in the third metacarpal bone of 2-year-old thoroughbred racehorses

Journal of Anatomy ◽

10.1111/j.0021-8782.2004.00354.x ◽

2004 ◽

Vol 205 (6) ◽

pp. 491-500 ◽

Cited By ~ 19

Author(s):

A. Boyde ◽

E. C. Firth

Keyword(s):

Metacarpal Bone ◽

The Third ◽

Calcified Cartilage ◽

Thoroughbred Racehorses ◽

Cartilage Canals

Download Full-text

Association of Catastrophic Condylar Fracture With Bony Changes of the Third Metacarpal Bone Identified By Standing Magnetic Resonance Imaging In Cadaveric Forelimbs of Thoroughbred Racehorses

Equine Veterinary Journal ◽

10.1111/evj.30_12732 ◽

2017 ◽

Vol 49 ◽

pp. 18-18

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Metacarpal Bone ◽

Resonance Imaging ◽

Condylar Fracture ◽

The Third ◽

Thoroughbred Racehorses

Download Full-text

Preexisting lesions associated with complete diaphyseal fractures of the third metacarpal bone in 12 Thoroughbred racehorses

Journal of Veterinary Diagnostic Investigation ◽

10.1177/1040638717704866 ◽

2017 ◽

Vol 29 (4) ◽

pp. 437-441 ◽

Cited By ~ 8

Author(s):

Sarah N. Gray ◽

Mathieu Spriet ◽

Tanya C. Garcia ◽

Francisco A. Uzal ◽

Susan M. Stover

Keyword(s):

Callus Formation ◽

Metacarpal Bone ◽

Diaphyseal Fracture ◽

The Third ◽

Bone Injury ◽

Thoroughbred Racehorses ◽

Metacarpal Bones ◽

Periosteal Surface ◽

Diaphyseal Fractures ◽

Bone Callus

We characterized features of complete diaphyseal fractures of third metacarpal bones in Thoroughbred racehorses. Given that stress fractures are known to occur in the third metacarpal bone, an additional aim was to determine if complete fractures are associated with signs of a preexisting incomplete stress fracture. Bilateral metacarpi from 12 Thoroughbred racehorses euthanized because of complete unilateral metacarpal diaphyseal fracture were examined visually and radiographically. Open, comminuted, transverse or short oblique fractures occurred in the middle of the diaphysis or supracondylar region. Periosteal surface discoloration and bone callus formation contiguous with the fracture line were present in fractured bones. All contralateral intact metacarpi had gross anatomic lesions, and 10 had radiographic abnormalities similar to those observed on fractured metacarpi. Catastrophic metacarpal fractures occurred in racehorses with bilateral evidence of preexisting bone injury.

Download Full-text