Effects And Mechanism Of Low Intensity Pulsed Ultrasound On Extracellular Matrix In Rabbit Knee Osteoarthritis

Objective:To observe the effects of low-intensity pulsed ultrasound on repairing extracellular matrix in rabbit knee osteoarthritis and analysis its mechanism.Methods:60 adult female rabbits,were randomly divided into two groups.All rabbits were replicated in right knees by Hulth method for knee osteoarthritis model.2 weeks after operation,the LIPUS group treated with LIPUS(the ultrasonic frequency is 800 ±5%KHz and the intensities(spatially averaged and time averaged,SATA)is 50±10%mw/cm2,once a day,every 20 minutes),while control group were given sham LIPUS treatment(the same operation with the LIPUS group but without energy output).After 2 weeks,4 weeks,8 weeks,10 rabbits in each group were randomly killed for each time.Observe the changes of cartilage and HE staining,analysis the expression of collagen type ?,proteoglycan,MMP-3,7 and 13 in cartilage by immunohistochemical and RT-PCR technique,analysis the expression of NO in cartilage by using nitrate reduction method,and results were analyzed by statistical software.Results:On the same observed time point,the damage degree of cartilage in LIPUS group is slighter than that in the control group(P<0.01),the expression of MMP-3,7,13 and NO in cartilage in LIPUS group is lower than that in control group(both P<0.01)while collagen type ? and proteoglycan is higher than that in control group(both P<0.01).The differences were significant.Conclusion:Low-intensity pulsed ultrasound repair the damaged cartilage by reducing the expression of MMP-3,7,13,inhibiting the secretion of NO and promoting the synthesis of collagen type ? and proteoglycan in cartilage.