Subchondral bone density and cartilage degeneration patterns in osteoarthritic metacarpal condyles of horses.
OBJECTIVE
To evaluate and correlate patterns of subchondral bone density and articular cartilage degeneration (derived by use of gross, histologic, and computed tomographic [CT] examinations) in equine third metacarpal condyles with and without osteoarthritis.


METHODS
8 metacarpophalangeal (MCP) joints (n = 4 horses) without osteoarthritis and 6 osteoarthritis-affected MCP joints (4).


METHODS
Horses were euthanized. The third metacarpal condyles of the joints were examined grossly and via CT (3 slice images/condyle). For 6 condylar zones, mean bone density and pattern of density distribution were determined. Data for osteoarthritis-affected and control joints were compared. Histomorphometric point count analyses identified areas of bone density for comparison with CT density measurements.


RESULTS
Osteoarthritis-affected condyles had heterogeneous subchondral bone with focal resorptive lesions and patterned sclerosis, whereas control condyles had symmetric bone density distribution. In osteoarthritis-affected condyles, bone density determined via gray scale image density analysis was greater (dorsal and medial pattern), compared with control condyles, and differed among zones because of resorption and sclerosis. With regard to bone density in osteoarthritis-affected condyles, histologic findings correlated with CT images, and bone lesions were significantly correlated with cartilage lesions.


CONCLUSIONS
In horses, heterogeneous distribution and greater subchondral bone density were characteristic of osteoarthritis-affected condyles, compared with control condyles. Subchondral bone lesions correlated with overlying cartilage lesions in osteoarthritis-affected MCP joints. Identification of CT image characteristics appears to predict the presence of a cartilage lesion in MCP joints of horses with osteoarthritis.
Comparative Orthopedic Research Laboratories, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
Benjamin D
BD
Young
Valerie F
VF
Samii
John S
JS
Mattoon
Steven E
SE
Weisbrode
Alicia L
AL
Bertone
D000818:Animals; D015519:Bone Density / Q000502:physiology*; D002356:Cartilage / Q000473:pathology*; D005552:Forelimb / Q000473:pathology; D006734:Horse Diseases / Q000473:pathology*; D006736:Horses; D007596:Joints / Q000473:pathology; D010003:Osteoarthritis / Q000473:pathology / Q000662:veterinary*