Effects Of Platelet-rich Plasma On Gradient Structure Regeneration After Injury Of Bone-tendon Junction In Rabbits

Objective: Exploration of the effect of platelet-rich plasma on gradient structure regeneration after tendon-bone junction injury in rabbitsParticipants and Methods: Thirty-six mature New Zealand rabbits were used to establish tendon-bone junction injury model after partial patellectomy.They were randomly divided into PRP treatment group and control group with 18 rabbits in each group.In the PRP treatment group(n=18),the prepared PRP was filled at the interface between the patellar tendon and the remaining patella before suturing the patellar tendon and the remaining patella.In the control group(n=18),only normal saline was used.At the 4th week(n=12)and 8th week(n=24),the rabbit patellar-patellar tendon complex tissue samples were collected.The control group(n=6)and the PRP group(n=6)were collected at the fourth week for histological observation and micro-laser Raman spectroscopy detection,and the control group(n=12)and the PRP group(n=12)at the eighth week were randomly divided into two parts.One part(n=6)was divided into two parts along the median sagittal axis,observed by histologically and detected by laser Raman spectroscopy,and the other part(n=6)was tested biomechanically.Histological observation was mainly performed by H&E staining to observe the morphological structure of the specimens;Laser Raman spectroscopy was used to observe the mine ralization degree and the change of organic matrix content of the specimens,and the length of new bone(NB),calcified fibrocartilage layer(CFC),uncalcified fibrocartilage layer(UCFC),fibrocartilage layer,calcified layer and the total length of the new structure were calculated.Biomechanical tests to evaluate the mechanical properties of specimens,including failure load and ultimate strength.Results: 1.At the 4th and 8th week after operation,the appearance of new bone and fibrocartilage in PRP group was earlier than that in control group,and the structure was neater than that in control group.2.Mineralization of tendon-bone interface occurred at the 4th and 8th weeks after operation.Tendon-bone complex had four layers of tendon,fibrocartilage,new bone and subchondral bone.At the 4th week,the length of new bone in PRP group increased by 116.67 ?m compared with that in control group(P<0.01).The length of new calcified fibrocartilage layer,new uncalcified fibrocartilage layer,new fibrocartilage layer,new calcified layer and new summary structure increased by 83.34 ?m,83.34 ?m,166.66 ?m,209.67 ?m and 283.33 ?m,with significant statistical significance(P<0.05);At the 8th week,the length of new bone,new calcified fibrocartilage layer,new uncalcified fibrocartilage layer,new calcified fibrocartilage layer,new calcified layer and new summary structure increased by 133.33 ?m,341.66 ?m,383.34 ?m,716.66 ?m,475.00 ?m and 758.33 ?m,respectively,compared with the control group(P < 0.01).3.At the 8th week after operation,the Failure Load and Ultimate Strength of tendon-bone complex in PRP group were larger than those in control group,and the Ultimate Strength increased by 0.9 MPa(P<0.05),and Failure Load increased by 54.71 N,with respectively significant statistical significance(P<0.01).Conclusion: Platelet-rich plasma can promote the regeneration of gradient structure and the recovery of mechanical properties of tendon-bone junction after injury,and increase the tensile strength of tendon-bone junction after injury.