| Objective Thoracic deformity is one of the common complications after multiple costal cartilages harvesting procedures.Although surgeons have made the remaining costal cartilage shredded and reimplanted it into the perichondrium pocket to reduce the probability of postoperative thoracic deformities,it is still a lack of regeneration strategy and quantitative data on how to maximize the use of the remaining cartilages.In this experiment,a rabbit animal model was constructed to simulate the process of thoracic injury after harvesting multiple costal cartilages in the human body,so as to study the effect of reimplanting autologous costal cartilage fragments of different diameters in the donor site’s perichondrium on the regeneration of the donor site.Method1.About 5mm long costal cartilages were taken from the 5-7th ribs on both sides in4 New Zealand white rabbits,while keeping the costochondral junction and perichondrium intact.Use a random number table method to determine the treatment methods for the defects of different donor sites before surgery(reimplanting cartilage fragments with the diameters of 0.7mm,0.6mm,0.5mm,0.4mm,0.3mm respectively and without reimplanting cartilage fragments).Each rabbit’s 6 costal cartilage defects were treated differently.Multi-slice spiral CT scanning and three-dimensional reconstruction was performed 4 months after the surgery to observe the general morphology of the thoracic cage and the repaired segments in each group.2.About 5mm long costal cartilages were taken from the 5-7th ribs on the right side in 36 rabbits and were divided into 6 groups randomly.Use a random number table method to determine the treatment methods for the defects of different donor sites in each group(reimplanting cartilage fragments with the diameters of 0.7mm,0.6mm,0.5mm,0.4mm,0.3mm respectively and without reimplanting cartilage fragments).The treatment methods of 3 costal cartilages defects in each rabbit were the same.Biomechanical performance testing,multi-slice spiral CT scanning and three-dimensional reconstruction were performed 4 months after the surgery.HE staining,Alcian blue staining,Masson trichrome staining,Ki67 immunohistochemical staining,type I collagen immunohistochemical staining,and type II collagen immunohistochemical staining were performed 1,4,and 6 months after surgery to explore the organization type in the repaired segments.Results1.Multi-slice spiral CT scanning and three-dimensional reconstruction indicated that when the diameters of the reimplanted cartilage fragments were 0.3mm or0.4mm,the volume of the donor site repair segment were the largest(p<0.05),and there was a strong correlation between the diameters of the reimplanted cartilage and the volume of the repaired segments.2.The absolute values of AI index in the reimplanted group were smaller than 0.05,indicating symmetric thoracic cage.The compressive modulus(p<0.05)of the reimplanted cartilage fragments group were better than those of the non-reimplanted group,and there was difference in compressive modulus of the repaired tissue at the donor site between 4 months and 6 months.(p<0.05).3.Immunohistochemical stainings indicated that there were Ki67-positive chondrocytes on the edge of cartilage fragments.After the costal cartilage fragments were reimplanted,the repaired tissue of the donor site showed blue stainings for Alcian blue,Masson stainings,and positive stainings for type I collagen and type II collagen.Conclusion1.In the early stage after costal cartilage harvesting,the improvement of thoracic deformity and the biomechanical properties of the reimplanted cartilage fragments group were better than those of the non-reimplanted cartilage fragments group,and the biomechanical performances of the reimplanted costal cartilage defects were increased over time.2.There was a phenomenon of cartilage cell proliferation at the interface of reimplanted cartilage fragments,and the repaired segment tissue was composed of chondroid tissue and fibrous tissue.When the diameter was smaller,the surface area of the fragments was larger,and more chondrocytes proliferation can be observed.3.In the observation for up to 6 months,the smaller reimplanted cartilage fragments(0.3mm and 0.4mm)can survive effectively.When the cartilage fragments were reimplanted for a longer time,the boundary between the fragments tended to be blurred,indicating that cells outgrew.4.The cartilage fragments in the 0.3mm and 0.4mm groups can obtain the largest volume in the repaired segments,larger glycosaminoglycan content and collagen fiber content,which were the best diameters in this study. |
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