Structural characterization of subchondral bone in the distal aspect of third metacarpal bones from Thoroughbred racehorses via micro--computed tomography.
OBJECTIVE
To characterize the microstructure of subchondral bone (SCB) plate and trabecular bone (TBB) of the distopalmar aspect of the condyles of third metacarpal bones (MC3s) from Thoroughbred racehorses at 2 different stages of SCB disease via micro-computed tomography (CT).


METHODS
12 pairs of MC3s from Thoroughbred racehorses euthanized for various reasons.


METHODS
MC3s were collected from horses with mild (n = 6) or severe (6) SCB disease, as determined via micro-CT. Cubic (6 x 6 x 6-cm) specimens of SCB plate and TBB were cut from the palmar aspect of condyles and sagittal ridges and examined with 3-dimensional micro-CT. For each specimen, apparent bone mineral density (aBMD), true BMD (tBMD), bone volume fraction (BVF), trabecular thickness (TBT), trabecular separation (TBS), and connectivity (CN) were calculated.


RESULTS
Condyles had higher aBMD, tBMD, BVF, and TBT and lower TBS than did the sagittal ridge. In bone specimens with mild SCB changes, SCB plate had higher aBMD, TBT, and CN and lower TBS than did TBB. In bone specimens with severe SCB disease, TBB had higher aBMD and TMD and lower TBS than it did in bone specimens with mild disease, and values were similar to those for SCB plate in bone specimens with severe disease.


CONCLUSIONS
The microstructure of SCB of the distopalmar aspect of metacarpal condyles of horses varied according to the severity of changes identified via micro-CT. With mild SCB disease, sclerosis existed in the SCB plate of the condyles; with severe disease, sclerosis also invaded condylar TBB.
Rubio-Martínez
Luis M
LM
Comparative Orthopedics Research Laboratory, Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON NIG 2W1, Canada.
Cruz
Antonio M
AM
Gordon
Karen
K
Hurtig
Mark B
MB
D000704:Analysis of Variance; D000818:Animals; D001847:Bone Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary*; D002102:Cadaver; D006734:Horse Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D006736:Horses; D050279:Metacarpal Bones / Q000000981:diagnostic imaging / Q000473:pathology* / Q000502:physiology; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D055114:X-Ray Microtomography / Q000662:veterinary