[Effect of intermittent negative pressure on matrix metalloproteinase 9 and transforming growth factor ß of tendon-bone interface and joint fluid after reconstruction of anterior cruciate ligament in rabbits].

Objective To study the effect of intermittent negative pressure on matrix metalloproteinase 9 (MMP)-9 and transforming growth factor β of tendon-bone interface and joint fluid after reconstruction of anterior cruciate ligament in rabbits. Methods A total of twenty-four New Zealand white rabbits were randomly selected hind leg of negative group, contralateral hind leg as control.Reconstruction of the anterior cruciate ligament was done by autogenous semitendinosus of rabbit.Joint of the negative pressure side placed drainage tube connecting the micro-negative pressure aspirator, and maintained an intermittent, low-intensity negative pressure.Control side placed ordinary drainage tube.Drainage tube of both sides was pulled out at the same time after 5 days.After 6 weeks, joint fluid and femur-ligament-tibia complex were obtained for study of expression of MMP-9 and TGF-β in joint fluid and tendon-bone interface. Result Twenty-three rabbits were included in the study because of one rabbit joint infections.Detection of joint fluid showed that MMP-9 content is significantly lower in negative group than that in the control group, and the difference is statistically significant [(8.9±1.3) pg/L vs (12.3±1.8) pg/L (P=0.002)]. TGF-β content is significantly higher in negative group in joint fluid than that in the control group, and the difference is statistically significant [(19.0±2.2) pg/L vs (15.2±1.4) pg/L (P=0.000)]. Study of immunohistochemistry in tendon-bone interface found that expression of MMP-9 is lower in negative pressure group than that in the control group, and the difference is statistically significant (P=0.000). TGF-β expression is significantly higher in negative group in tendon-bone interface than that in the control group, and the difference is statistically significant (P=0.000). Conclusion Intermittent negative pressure may reduce content of MMP-9 in joint fluid and expression of MMP-9 in tendon-bone interface, increase content of TGF-β in joint fluid and expression of TGF-β in tendon-bone interface after reconstruction of anterior cruciate ligament in rabbits. Key words: Anterior cruciate ligament; Negative pressure; Tendon-bone healing; Matrix metalloproteinase 9; transforming growth factor β