| Objective:Because of the lack of innervations,blood supply and articular cartilage lymph circumfluence,the self-repair ability after cartilage damage was quite limited.How to deal with the knee joint cartilage full-thickness injury has been a big problem in the field of orthopaedics.The clinical surgical methods included tissue transplantation and cell transplantation which were only in the experimental stage and they were too expensive to be applied in clinical treatment.The microfracture technique repaired the defects through stimulate the bone marrow mesenchymal stem cell differentiation into cartilage cells and the platelet-rich plasma healed the tissues by cell activation and the concentration of growth factors.Since the latter two provided seed cells and growth factors similar in tissue engineering and could be easily operated,microfracture technique combined with platelet-rich plasma was a promising research field but with limited findings.This study was designed to compare the histologic changes of the repaired cartilage in full-thickness defects under different treatment methods and during different periods.Meanwhile,it was aimed to explore the curative effect of microfracture technology combined with platelet-rich plasma for the treatment of articular cartilage defects and to provide a theoretical basis and practical guidance for clinical treatment.Methods:1 Grouping and model preparation:Take 48 New Zealand white rabbits.The A,B,C,D four groups were randomly divided,12 rabbits in each group.Full-thickness cartilage defect models were manufactured in the weight-bearing area of the medial femoral condyle of the right knee.Group A: no treatment for the cartilage defects;Group B:platelet-rich plasma was injected into the knee;Group C:processing microfracture surgery in cartilage defect area;Group D:processing microfracture surgery in cartilage defect area and injecting platelet-rich plasma into the knee.2 Blood collection:In B and D groups,each experimental rabbit was extracted about 7-9ml venous blood in the ear marginal vein.While 5ml of the blood was injected into vacuum tube of the lithium heparin anticoagulant,2ml was injected into the vacuum tube of the EDTA-K2 anticoagulant as preparation.3 Preparation of the PRP:5 ml of the venous blood was used quadratic centrifugation method.Firstly,centrifuge the blood at the speed of 2000 r/min,time 10 min,and secondly repeat it at the same speed and time.The prepared PRP is about 0.5 ml for being injected in intraoperatie articular cavity.4 Platelet counting:Take 2ml vein blood with EDTA-K2 anticoagulanted into hemocytometer to get the amount of the platelets.Use the same centrifugation method to get PRP and later count the platelets again to validate if the prepared PRP meet the required experimental standard.5 Observations:Respectively after 8 weeks and 12 weeks,randomly selected 6 rabbits were put to death.Randomly selected 5 rabbits were put to observe in each group.Cut their joint capsule open and expose the medial femoral condyle weight-bearing area of the right knee for further observation.Then evaluate this condition according to the standard.Sample tissue section from the damage repair parts and use HE and Toluidine blue staining.Fix 2% glutaraldehyde solution of other specimen for electron microscopy(scanning electron microscope and SEM).The changes in tissues were observed by electron microscopelight and microscope after the histological production.Results:1 General observation:after 8 weeks,Group A:The defect repair tissue failed to smooth repair cartilage defects,the defect area and the surrounding normal cartilage boundaries clear;Group B:The defect repair tissue could repair cartilage defect relatively smooth,there were relatively vague boundaries between repaired area and surrounding normal cartilage;Group C:The defect repair tissue could repair cartilage defect relatively smooth,there were relatively vague boundaries between repaired area and surrounding normal cartilage.Group D:The defect repair tissue could repair cartilage defect relatively smooth,there were vague boundaries between repaired area and surrounding normal cartilage.After 12 weeks,Group A:The defect repair tissue failed to smooth repair cartilage defects,there were visible significant depression in the cartilage defect;Group B:The defect repair tissue failed to smooth repair cartilage defects,there were clear boundaries between repaired area and surrounding normal cartilage;Group C:The defect repair tissue could repair cartilage defect relatively smooth,there were relatively clear boundaries between repaired area and surrounding normal cartilage;Group D:The defect repair tissue could repair cartilage defect smoothly,there were relatively vague boundaries and similar color between repaired area and surrounding normal cartilage.2 Histological observation:After eight weeks,Group A:microscope visible cartilage defect area disordered arrangement of new cells,and normal cartilage tissue border there is a fracture;Group B:microscope visible cartilage defect area cell hyperplasia is relatively strong and rich,with an array of directional;Group C:microscope visible cartilage defect area of cartilage cell proliferation exuberant and normal cartilage tissue interface there is a fracture;Group D:microscope visible cartilage defect area cell hyperplasia and rich,with an array of directivity,a small number of new cartilage approximate hyaline cartilage.After 12 weeks,Group A:microscope visible cartilage defect area has not seen obvious cartilage tissue hyperplasia,along with the cell hyperplasia exuberant disordered arrangement of basic groups for fibrous connective tissue;Group B,C:microscope visible cartilage defect area cell hyperplasia and rich,with an array of directional,fuzzy border area,integration is good,did not see clearly show the distribution of the clusters of abundant fibrous connective tissue hyperplasia area,there is a small amount of cells like transparent cartilage cell differentiation;Group D:microscope cartilage damage zone cell hyperplasia and rich,directional arrangement,with an array of directional,part of the new cartilage nearly transparent cartilage.3 Electron microscope observation:Normal cartilage:electron microscope visible normal cartilage area surface smooth,No surface shrinkage texture and distortion;Making samples immediately after the operation:Normal cartilage area with defect area visible step change obviously,normal cartilage area smooth and neat,does not appear to shrivel liberal arts,defect surface is uneven, the rutted road surface is uneven;After 12 weeks,Group D:electron microscope visible the defect area with the surrounding normal cartilage boundaries was clear,the defect repair tissue close to the front fork lateral ligament slightly neat.Conclusion:1 Microfracture technique,platelet-rich plasma,or a combination of both could effectively promote full-thickness cartilage defect repair.2 The effects of microfracture technique or platelet-rich plasma for cartilage repair started to degenerate after 12 weeks while compared with 8 weeks group did not have obvious change.3 The effects of microfracture technique combined with platelet-rich plasma for cartilage repair didn’t started to degenerate after 12 weeks while compared with 8 weeks group did have good results.It wase an effective method for the treatment of full-thickness cartilage defects. |
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