Measurement of articular cartilage stiffness of the femoropatellar, tarsocrural, and metatarsophalangeal joints in horses and comparison with biochemical data.
OBJECTIVE
To determine normal cartilage stiffness values in different weight-bearing and non-weight-bearing areas of 3 different equine joints, and to evaluate the relationship between cartilage stiffness and glycosaminoglycan (GAG) and collagen content.


METHODS
Compressive stiffness of the articular cartilage was measured in 8 horse cadaver femoropatellar (FP), tarsocrural (TC), and metatarsophalangeal (MT) joints. Gross evaluation, collagen content, GAG content, and histologic appearance were assessed for each measurement location.


METHODS
Eight equine cadavers (4 intact females, 4 castrated males; 7 Quarter Horse or Quarter Horse type, 1 Arabian; aged 4-12 years, weighing 400-550 kg).


METHODS
The articular surfaces of 8 equine cadaver FP, TC, and MT joints were grossly evaluated for signs of articular cartilage pathology. Stiffness at preselected sites (FP joint-6 sites; TC joint-3 sites; MT joint-4 sites) was determined using an arthroscopic indentation instrument. Biochemical composition (collagen, GAG content) and histologic evaluation (modified Mankin score) were assessed for each measurement site.


RESULTS
All cartilage from all sites evaluated was determined to be normal based on macroscopic and histologic assessments. No significant correlation between Mankin scores and cartilage stiffness values was observed. Site differences in cartilage stiffness were measured in all 3 joints (P<.001). GAG or collagen content had a significant positive correlation with stiffness values in 6 of 13 sites (P<.05, r>0.622, r2>0.387).


CONCLUSIONS
Relative cartilage stiffness values measured in healthy equine joints are site dependent and can be measured using an indentation device intended for arthroscopic application.


CONCLUSIONS
An indentation instrument provided an objective means of determining relative compressive stiffness of articular cartilage. Further research needs to be performed to confirm the site and joint differences observed in this study in clinically normal horses and to determine if the tester can be used clinically to predict articular cartilage pathology.
Garcia-Seco
Elena
E
Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211, USA.
Wilson
David A
DA
Cook
James L
JL
Kuroki
Keiichi
K
Kreeger
John M
JM
Keegan
Kevin G
KG
D000818:Animals; D001696:Biomechanical Phenomena; D002102:Cadaver; D002358:Cartilage, Articular / Q000737:chemistry / Q000473:pathology / Q000502:physiology*; D003094:Collagen / Q000032:analysis*; D019245:Compressive Strength / Q000502:physiology*; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis*; D006736:Horses; D008297:Male; D008683:Metatarsophalangeal Joint / Q000737:chemistry / Q000473:pathology / Q000502:physiology*; D013640:Tarsal Joints / Q000737:chemistry / Q000473:pathology / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology
D006025:Glycosaminoglycans; D003094:Collagen