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[The chondroprotective effect of intra-articular hyaluronic acid at early stages of osteoarthritis: an experimental study in rabbits].

OBJECTIVES
Hyaluronic acid (HA) is used in osteoarthritis, especially for the control of pain. In this study, we investigated the effect of intra-articular HA on experimental osteoarthritis of early stage.


METHODS
Osteoarthritis was induced in both knees of 10 rabbits by transecting the anterior cruciate ligament under intramuscular anesthesia with ketamine and xylazine. Intra-articular HA at a dose of 0.6 ml (15 mg/ml) and physiologic saline solution (0.6 ml) were injected into the right and left knees, respectively, three times with a week interval. Three rabbits died during the study period and were excluded. The remaining rabbits were sacrificed in the 12th week via high dose anesthesia to remove the distal femora for histological evaluation using the Mankin scale and for measurements of the cartilage area.


RESULTS
The mean cartilage areas calculated in HA- and saline-injected knees differed significantly (1.097 mm2 and 0.477 mm2, respectively; p<0.05). The overall mean Mankin score was significantly lower in HA-injected knees (3.57 versus 11.14; p<0.05). Although, there were no significant differences between the two groups with respect to cellular abnormality, matrix staining, and tidemark continuity (p>0.05), the mean scores for the structure of the cartilage were significantly different (0.86 versus 4.43; p<0.05). The integrity of the tidemark was preserved in all the HA-administered knees, though a notable disruption was observed in four control knees.


CONCLUSION
Our results suggest that HA delays the development of osteoarthritis at early stages through exerting a chondroprotective effect.