High density infill in cracks and protrusions from the articular calcified cartilage in osteoarthritis in standardbred horse carpal bones.
We studied changes in articular calcified cartilage (ACC) and subchondral bone (SCB) in the third carpal bones (C3) of Standardbred racehorses with naturally-occurring repetitive loading-induced osteoarthritis (OA). Two osteochondral cores were harvested from dorsal sites from each of 15 post-mortem C3 and classified as control or as showing early or advanced OA changes from visual inspection. We re-examined X-ray micro-computed tomography (µCT) image sets for the presence of high-density mineral infill (HDMI) in ACC cracks and possible high-density mineralized protrusions (HDMP) from the ACC mineralizing (tidemark) front (MF) into hyaline articular cartilage (HAC). We hypothesized and we show that 20-µm µCT resolution in 10-mm diameter samples is sufficient to detect HDMI and HDMP: these are lost upon tissue decalcification for routine paraffin wax histology owing to their predominant mineral content. The findings show that µCT is sufficient to discover HDMI and HDMP, which were seen in 2/10 controls, 6/9 early OA and 8/10 advanced OA cases. This is the first report of HDMI and HDMP in the equine carpus and in the Standardbred breed and the first to rely solely on µCT. HDMP are a candidate cause for mechanical tissue destruction in OA.
Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, Saint-Hyacinthe, QC J2S-7C6, Canada. sheila.laverty@umontreal.ca.
Sheila
S
Laverty
Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, Saint-Hyacinthe, QC J2S-7C6, Canada. matlacourt@gmail.com.
Mathieu
M
Lacourt
Division of Experimental Medicine, McGill University, Montreal, QC H3G-1A4, Canada. chan.gao@mail.mcgill.ca.
Chan
C
Gao
Bone Engineering Labs, Research Institute-McGill University Health Centre, Montreal General Hospital C9-133, 1650 Cedar Ave, Montreal, QC H3G-1A4, Canada. Janet.henderson@mcgill.ca.
Janet E
JE
Henderson
Dental Physical Sciences, Oral Growth and Development, Dental Institute, Barts' and The London School of Medicine and Dentistry, Queen Mary University of London (QMUL), London E1 4NS, UK. a.boyde@qmul.ac.uk.
Alan
A
Boyde
D000818:Animals; D002114:Calcinosis / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D002348:Carpal Bones / Q000000981:diagnostic imaging / Q000473:pathology*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology*; D006736:Horses; D010003:Osteoarthritis / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology*; D011857:Radiographic Image Interpretation, Computer-Assisted; D013314:Stress, Mechanical; D055114:X-Ray Microtomography