OBJECTIVETo observe the influence of intra-articular injection of sodium hyaluronate (SH) on the expression of inducible nitric oxide synthase (iNOS) in the synovium and nitric oxide (NO) content in synovial fluid of rabbits with traumatic osteoarthritis (OA).

METHODSSixteen white rabbits underwent unilateral anterior cruciate ligament transection and were randomly divided into 2 groups 5 weeks after the operation. Rabbits in the experimental group received intra-articular injection of 0.3 ml of 1% SH, once a week for 5 weeks. Animals in the control group were treated under the same conditions using physiological saline. All the animals were sacrificed at the 10th week after surgery. The mRNA expression of iNOS in the synovium was analyzed using reverse transcription-polymerase chain reaction. The content of NO in the synovial fluid was assayed.

RESULTSThe level of iNOS expression of the synovium in the experimental group was lower than that in control group (0.47+/-0.09 vs. 0.65+/-0.12, t equal to 3.45, P less than 0.01). Compared with control group, the content of NO decreased significantly in synovial fluid of SH injection group (134.11 micromolar/L +/- 12.47 micromolar/L vs. 152.17 micromolar/L +/- 15.69 micromolar/L, t equal to 2.55, P less than 0.05).

CONCLUSIONSSH significantly decreases the content of NO in the synovial fluid of rabbits with traumatic OA. SH may exert the effect on synovial fluid NO level as a result of the suppression of iNOS expression in the synovium. It may be one of the mechanisms of the therapeutic effect of SH on early traumatic OA.