The Effect Of Pulsed Ultrasound Therapy On Medial Collateral Ligament Repair In Rats

Objectives:The purpose of the study was to investigate whether and how the administration of pulsed ultrasound therapy affects medial collateral ligament healing in rats.Methods:A totle of 18 3-month-old male Sprague-Dawley rats with transected medial collateral ligaments were studied.There were 18 knees. When the models are successful,subjects were randomly divided into 3 groups,which include group A,group B and group C.Group A was not given any treatment.Group B and group C were given 10-min pulsed ultrasound therapy(duty cycle:one application in 3 ms;1:3)daily with different intensities(0.5,1.0 W/cm~2).All rats were given the treatment for 8 days All rats were killed on the 9th day postoperatively.After macroscopic examination,MCLs were harvested and were researched by haematoxylin-eosin staining,VG-staining and immunohistochemical techniques in order to measure the level of transforming groth factor beta- 1(TGF-β1)and know the results of histological and histochemical scoring system.Results:1.Macroscopically,lacerated MCL healed by scar tissue formation, the amount of which appeared to be greater in 1.0,0.5 W/cm~2 group than in 0 W/cm~2 group.2.The appearance of HE-staining and VG-staining:There were significant differences of collagen fiber extent between group A,group B, group C.The amount of inflammatory cells appeared to be more in 1.0,0.5 W/cm~2 group than in 0 W/cm~2 group.3.The integrated optical density(IOD)of TGF-β1:In the 1.0 and 0.5 W/cm~2 groups,the levels of TGF-β1 were significantly up-regulated (p＜0.05).The 1.0 W/cm~2 group also registered higher expression of TGF-β1 than did the the 0.5 W/cm~2 group(p＜0.05).Conclusions:1.Rats with isolated MCL transect injury will get healed with non-operative treatment.2.After administration of pulsed US,Healing MCL appeared to have more scar tissue and fiber appeared to be more regulated,which pulsed ultrasound can improve ligament healingin the nea future,however if long-term treatment with this therapy could obtain further improvement is unkown.3.The levels of TGF-β1 were significantly up-regulated in pulsed ultrasond therapy group(p＜0.05).The 1.0w/cm~2 group also registered a significantly higher expression of TGF-β1 than did the 0.5w/cm2 group (p＜0.05).The prensnt findings suggests that pulsed US can increase the level of TGF-β1,which will be higher with higher dose application.4.Pulsed ultrasound therapy(US)may inhance ligament repair by up-ragulating the extent of TGF-β1.