| BackgroundWith nationwide fitness campaign and country’s athletic level advancing, the incidence of closed Achilles tendon rupture increases gradually. The treatments of closed Achilles tendon rupture contains surgery and nonoperative therapy in clinical. Surgery has lots of complications postoperatively, as well as high cost. Meanwhile, the nonoperative treatment can cause second Achilles tendon rupture. Therefore, it has important clinical significance to investigate the effective treatment which can reduce the incidence of second Achilles tendon rupture and promote the healing of Achilles tendon with nonoperative therepy.Platelet-rich plasma(PRP) is extracted from the whool blood. And it is rich in many growth factors, including platelet-deived growth factor(PDGF), transforming growth factor-B(TGF-B), vascular endothelial growth factor(VEGF), insulin-like growth factor(IGF) and basic-fibroblast growth factor(bFGF), and so on, which can promote repairing in wound healing. PRP is extracted from autologous peripheral blood in the patients, and high concentration of platetes can be obtained after centrifuged. Owing to containing high platelet content and all kinds of cell factors in the blood, PRP has been a hot spot as a nonoperative treatment of closed Achilles tendon rupture in clinical research.Since PRP was applied in the trauma orthopeadics, many studies had reported the interaction between platelets in PRP and the growth factors. PRP can promote the damaged tissues to repair under the comprehensive effect of the growth factors. However, some studies showed that PRP had no active effect on the healing of injured tissues. So, it is still controversy about the application of PRP in trauma orthopaedics. We took the rats for experiment. The Achilles tendons of rats were transected. We observed the fibers regeneration and histological, biomechanical variation. In additions, we also expored the effect and the effective healing time of closed Achilles tendon rupture after PRP injection. It was hoped to provide the theoretical basis for clinical practice of PRP.ObjectiveAfter injecting PRP around the Achilles tendon, to observe the effect of platelet-rich plasma injection on the early healing of rat’s Achilles tendon rupture so as to provide the experimental basis for clinical practice.Methods1. Preparation of PRPThe ten donar SD rats was anesthetized with pentobarbital. The blood was collected by cardial puncture with a heparinized syringe. The blood was then centrifuged with Landesberg method. The platelet-poor plasma(PPP) at the top centrifugal tube was moved by manual pipettes. It was set aside. The residual supernanant was abandoned. So the PRP was prepared.2. rats groupThe thirty-six rats were randomly devided into three groups with random digital tables. It was the blank group, PPP group and PRP group, respectively. And each group had twelve rats.3. rats model and intervationThe rats were anesthetized with pentobarbital. Under aspetic conditions, the bilateral Achilles tendons of the rats were cut transversely7mm proximal to its calcaneal insection and a2mm long segment was removed to enlarge the defect. The wound was closed after the surgical procedure. Then, the rats were injected PPP or PRP around the Achilles tendon in the PPP group and PRP group, respectively. The quantity of injection was100ul in each side of the rats. And the rats in blank group were not injected with PPP or PRP. The rats were injected once with100ul PPP or PRP weekly in PPP group or PRP group, till the rats were killed. The legs of the rats were not fixed with plaster or splint. The rats had free activity in the cages. And all of the rats were injected with penicillin for three days to prevent infection postoperatively.4. outcome observationWe observed the activity and wound of the rats postoperatively, as well as the healing and adhesion of the tendon. And we took grading of tendon adhesion in every group at four weeks. The tendon tissue samples were harvest after operation for immunolistochemical staining. We also observed the new blood vessels, fibroblasts and inflammatory cells under a microscope.5. outcome measureThe positive density values of type I collagen fibers were calculated by an image analysis software. The biomechnical test which was consisted of the most gliding excursion, elasticity modulus and the ultimate tensile strength was implemented at four weeks in3groups.6.StatisticsThe statistical analysis software SPSS13.0was used for the data analysis. The measurement data was presented with mean(±SD). The comparison between groups was analyzed with ANOVA, the LSD multiple comparison was used when variance analysis is significant, if not, Dunnett method was used. Ranked data was examined using Kruskal-Wallis test. And the significant difference was P value(<0.05).Results1. All the animals survived till the end of the experiment. Tendon edema gradually decreased and sliding improved with time. The tendon adhesion increased steadily from1week to3weeks postoperatively, and it was relieved at4weeks in3groups. There were no significant differences in the grading of tendon adhesion at4weeks in3groups (χ2=1.432;P=0.489).2. The inflammatory cell infiltration, angiogenesis and collagen fibers were more in PRP group than in group PPP and control group at1week; with time, inflammatory cell infiltration and angiogenesis gradually decreased. Positive staining of type I collagen fibers was observed at1-4weeks postoperatively. The positive staining of collagen fibers in group PRP was significantly higher than that in control group and PPP group at the1,2and3weeks (F=428.242;P=0.000, F=12.030;P=0.001, and F=70.684;P=0.000, respectively), but no significant differences was found between three groups at4weeks(F=2.714, P=0.107).3. The biomechanical tests showed:there was no significant statistical differences in the most gliding excursion between3groups at4weeks postoperatively (F=2.132, P=0.144). The elasticity modulus and the ultimate tensile strength of PRP group were significantly higher than those of control group and PPP group at4weeks (F=16.242;P=0.000, and F=20.593;P=0.000).ConclusionsAfter injecting PRP around the Achilles tendon, the PRP can promote capillary regenerationon and reduce the inflammation on the early healing process of Achilles tendon rupture in rats. PRP injection can promote the proliferation of type I collagen fiber in Achilles tendon, and can increase the strength and rigidity of Achilles tendon. Platelet-rich plasma injection can improve the healing of Achilles tendon in early repair of rat’s Achilles tendon. |
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