Experimental Study Of Costal Interal Distraction

Part 1: 3-D measurement and digital modeling of congenital thoracic deformity.ObjectiveTo establish the three-dimensional digital model of congenital thoracic deformity by using CT scan data and discuss the application prospects of three-dimensional digital model,which would help to build the entity model and design the templates of rib defects during the thoracic contour plastic surgery.Methods22 patients with thoracic deformity including poland syndrome,funnel chest and ribs defects all received continuous volumentric scanning of chest with 64 slice spiral CT by which data acquisition was done and 3-D reconstruction was performed.The digital data model of thorax was established after the scanning data was processed by the Mimics 17.0 software and the entity model could be made by 3D printers with these processed data.Digital data model of normal thorax was also reversed by the mirror method.The data difference between these two models was calculated which would help design the rib templete and guide the thoracic contour plastic surgery.ResultsThese 22 cases with thoracic deformity were established completely with digital data models and gained entity models by 3D printers.Also 11 cases of normal digital data models were collected.ConclusionDigital model of thoracic deformity was established by Mimics 17.0 software with processed CT scan data.Digital model of normal thorax was also reversed by the mirror method.3D printers helped us gained entity models,which would help to design more accurate and personalized thoracic contour plastic surgery in the future.Part 2: Establishment of rabbit rib defect modelObjectiveTo establish an animal model of rib defect and evaluating the effect of the distraction process during rib distraction osteogenesis in rabbits,which gives reference for the further clinic application.Methods10 adult New Zealand rabbits were selected.In the fourth rib close to the sternal,Unilateral rabbit rib defect(cut rib about 4 cm long and the rib membrane about 3 cm long)was fabricated according to the curvilinear DO designation and residual ribs embedded in rib periosteum.Results2 cases died of anesthesia problem,8 cases of rabbits were alive.Using CT scan and twice osteogenesis surgery we can confirm the defect of the rib share a similar extent with the rib removed in the surgery.ConclusionsBy cutting and embedding rib and its periosteum,rib defect model could be made.It provided an important tool to study the treatment of the rib defect and distraction experiment.Part 3: Design of rib extension device and a new study of rib distraction osteogenesis:a novel experimental designObjective: Distraction osteogenesis(DO)is a surgical procedure that the bone regenerate and regenerating and extending.Our study aims to establish a rabbit animal model of rib DO,and one distractor is designed and study the advantage and disadvantage of the rib distractor which was designed and made in the experiment of an animal rib DO.Methods:Ten rabbits were underwent unilateral costectomy and installed the specific distractor.Two rabbits died of anesthesia.8 adult New Zealand rabbits(weight4.150±0.550kg)underwent rib osteotomies with lateral placement of distraction device and cut the ribs at about 4 cm of its rib stump.3 days after surgery,the distraction was proceeded on one side of each rabbit for 25 days.All the rabbits were divided into 2 groups.One group were killed after 15-day fixation,and the other ones were killed after 30-day fixation.All the fresh specimens were immobilized with 10% formalin for 48 h,decalcifed with EDTA for 3-4weeks,paraffin-embedding and serial sectioning.Then the two sections were examined separately with electron microscope and deflection test.Results:It was successful to make the rib distractor which was used for the distraction of 8 rabbits ribs.There was a 3-day latent period,0.6mm of twice per day.Every rib was extended 40 mm.The extended rib reached the knitting bony union without delayed union,nonunion,angulation deformity.Imaging study showed that there was involucrum around the periosteum in the earlier distraction.With the distration,the osteotylus lump was growing and extending from the resection ends to the middle.The cortex of the rib which was not continuous emerged in the group of 15-day fixation was higher and uneven density osteotylus.The cortex of the bone was continuous.And the bone trabecula and fibrous tissue were arranged in the direction of osteogenesis which share the same arrangement with normal bones.Conclusions:We established and characterized an animal model of rib DO that outlines valid biologic controls.The rib distracor was lightweight,good stability,simple structure,easy to perform,integrity and high precision of distraction,which was applied in the rabbits rib DO.This experiment proved the quality of the DO was excellent and it could be was expected to be an approach to treat the rib defect.Part 4: Research on formation and deflection of the regenerative extension ribsObjectiveTo prove that the quality of the extended bone and the normal bone was the same with histomorphometrical change and deflection test.Methods: Compare the change of histomorphometric and ultramicro structure of the extended bone with 15 th day of consolidation,the extended bone with 30 th day of consolidation and to the normal ribs.Test the bone deflection of the 15 th,30th days of consolidation and normal ribs,make the deflection curved line,compare the deflection change and evaluate the result of the distraction.Results : Two rabbits died of anesthesia.8 rabbits were in the research.The regenerative rib was immature at the15 th days.The 30-day-formed regenerative costal bone was in accordance to the normal side rib even observed by optical microscope and when histomorphometrical measurement was compared statistically,there was no significant difference in the average extent of regenerative bone between the CDO with normal rib.However,there was no significant difference in the histomorphometric and ultramicro structure and deflection between 30-day fixation bone and the normal.ConclusionsThe extended bone with 15-day fixation was growing and remolding,which was not stable.The research presented that 30 days consolidation can obtain high quality regenerative new bones which could provide plenty of tissues to repair costal defects and its physiological function could reach the normal rib through distraction after 30-day fixation,it provided the experiment basis for study the treatment of the rib defect.