To assess whether the combination of hyaluronan, sodium chondroitin sul-fate, and N-acetyl-d-glucosamine (HCSG) lubricates articular cartilage in vitro and modulates joint lubrication in vivo.
16 healthy adult horses.
The effects of HCSG injections on SF lubricant properties and joint health, immediately after injury and 2 weeks later, were analyzed by use an equine osteochondral fracture model of post-traumatic osteoarthritis (OA). Middle carpal joints of adult horses were randomly assigned to 1 of 4 surgical treatment groups as follows: normal nonsurgical group (n = 8), normal sham-surgical group (8), OA-induced surgical group with HCSG injection (8), or OA-induced surgical group with saline (0.9% NaCl) solution injection (8). Synovial fluid was aspirated periodically and analyzed for boundary lubrication function and lubricant molecules. At 17 days, joints were screened for gross pathological changes.
Induction of OA led to an impairment of SF lubrication function and diminished hyaluronan concentration in a time-dependent manner following surgery, with HCSG injection lessening these effects. Certain friction coefficients approached those of unaffected normal equine SF. Induction of OA also caused synovial hemorrhage at 17 days, which was lower in joints treated with HCSG.
CONCLUSIONS AND CLINICAL RELEVANCE
After induction of OA, equine SF lubricant function was impaired. Hyaluronan-sodium chondroitin sulfate–N-acetyl-d-glucosamine injection restored lubricant properties at certain time points and reduced pathological joint changes.
Objective—To determine and correlate subchondral
bone mineral density and overlying cartilage structure
and tensile integrity in mature healthy equine stifle
(low magnitude loading) and metacarpophalangeal
(high magnitude loading) joints.
Animals—8 healthy horses, 2 to 3 years of age.
Procedure—Osteochondral samples were acquired
from the medial femoral condyle (FC) and medial
trochlear ridge (TR) of the stifle joint and from the
dorsal (MC3D) and palmar (MC3P) aspects of the distal
medial third metacarpal condyles of the
metacarpophalangeal joint. Articular cartilage surface
fibrillation (evaluated via India ink staining) and tensile
biomechanical properties were determined. The
volumetric bone mineral density (vBMD) of the
underlying subchondral plate was assessed via dualenergy
Results—Cartilage staining (fibrillation), tensile moduli,
tensile strength, and vBMD were greater in the
MC3D and MC3P locations, compared with the FC
and TR locations, whereas tensile strain at failure was
less in MC3D and MC3P locations than FC and TR
locations. Cartilage tensile moduli correlated positively
with vBMD, whereas cartilage staining and tensile
strain at failure correlated negatively with vBMD.
Conclusions and Clinical Relevance—In areas of
high joint loading, the subchondral bone had high
vBMD and the articular cartilage surface layer had
high tensile stiffness but signs of structural wear (fibrillation
and low failure strain). The site-dependent
variations and relationships in this study support the
concept that articular cartilage and subchondral bone
normally adapt to physiologic loading in a coordinated
way. (Am J Vet Res 2005;66:1823–1829)