The Application Of Three-Dimensional Laser Scanning Technique In The Movement Of Postauricular Expander And Change Of Expanded Skin Area

Objective:To study the change of the position of the post-auricular expander during the expansion maintenance period.Offer theoretical proof for the exact location of the expander implantation and determine a reasonable expansion maintenance time,enhance the effective expansion and increase the available expanded skin area.Methods:A total of 74 cases of patients of unilateral microtia who underwent post-auricular expander implantation between 2007 and 2009 in Auricular Reconstructive Center of plastic surgical hospital of Chinese Academy of Medical Sciences.The Selected criteria of the patients was:1.Aged 6～9 years old.2.The patient must be typeâ… ,typeâ…¡microtia.3.The patients had no previous laser depilation history and no previous surgery history, the post-auricular skin was intact,there is no scar and no tag was left. 4.In the post-auricular skin,the hairline was normal.5.No necrosis of expanding post-auricular flaps was occurred.6.No expander leakage and infiltration was occurred during expansion period.7.The patients could co-operate to the scanning work.Obtained the scanning digital model of post-auricular of expanders by the three-dimensional laser scanning technique before the expansion maintenance period and after the expansion maintenance period respectively,measured the movement distance of three mark point by overlay of the two three-dimensional digital modles with polyworks software,the available data and the affected factors such as sex, type of microtia,injected saline volume,expansion maintenance period and the flap hematoma were analyzed by multivariate linear regression.Result:All of the patients aged 6-9 years old,average 7.7 years old.43 of them was male,31 was female.26 was typeâ… microtia,48 was typeâ…¡microtia. Hematoma occurred in 10 cases.The injected saline volume was 53～87ml, average 70.4ml.The expansion maintenance period ranged was 20～50 days, average 29.6 days.The movement distance of the superior base point(SBP) ranged from 5.0 to 13.8mm,average 8.5mm,the movement distance of inferior basis point(IBP) ranged from 4 to 10mm,average 6.3mm,the movement distance of the inferior polar point(IPP) ranged from 4.3 to 12mm,average7.5mm.The available data were analyzed and three multiple linear regression equation models were drawn:SBP=-11.35+2.05×H+0.14×D+0.22×V,IBP＝-8.24+0.66×H+0.1×D+0.17×V,IPP＝-10.37+1.87×H+0.11×D+0.20×V.V=injected saline volume,D=expansion maintenance period,H＝flap hematoma.Conclusion:1.For the post-auricular expander,the expansion effect will change over time and the marking points position will moved downward after the expansion maintenance period,which due to the insufficient skin coverage of the auricular cartilage framework.2,Besides the position of the remnant ear,hairline and the normal auricle, the movement of expander after expansion maintenance period was another factors which should be considered when expander implantation.3,For the patients aged from 6-9 years old,the movement of the expander was unrelated to sex and the type(typeâ… and typeâ…¡) of the remnant ear,however,the injected saline volume,the expansion maintenance period and the flap hematoma affected the movement of the expander positively.Among the factors,the injected saline volume effect the most,then followed the expansion maintenance period,the flap hematoma effect finally. Objective:To study the change of the expanded surface-area during the expansion maintenance period by measuring the whole expanded surface-area of post-auricular expander and the surface-area of three equal part of the post-auricular expander,to explore the relationship between the expanded surface-area tissue expander and the injected saline volume primarily.Offer theoretical proof for effective expansion and Quantitative expansion.Methods:A total of 57 cases of patients of unilateral microtia who underwent post-auricular expander implantation between 2007 and 2009 in Auricular Reconstructive Center of plastic surgical hospital of Chinese Academy of Medical Sciences were selected.The selected criteria of the patients was: 1.Aged 6～9 years old.2.The patients must be typeâ…¡microtia.3.The patients had no previous laser depilation history and no previous surgery history.The post-auricular skin was intact and no scar or tag was left.4. In the post-auricular skin,the hairline was normal,facial soft tissue presents symmetry.5.No necrosis of expanding post-auricular flaps was occured.6.No expander leakage and infiltration was occurred during expansion period.7.The patients could co-operate to the scanning work. Obtained the scanning digital model of post-auricular of expanders by the three-dimensional laser scanning technique and measured the expanded surface-area before the expansion maintenance period(S₁) and after the expansion maintenance period(S₂) by polyworks software,the difference of expanded surface-area were analyzed by T test,the relationship between the expanded surface area and the injected saline volume were analyzed by simple linear regression.Result:1.Among all of the 57 patients,aged 6-9 years old,average 7.9 years old. The injected saline volume was 53～87ml,average 70.3m1(70.3.0±7.6).The expansion maintenance period was 30±2 days.We got equations expressed the relationship between the expanded surface area and the injected saline volume:S₁=599.36+77.15×V.S₂=505.99+75.45×V,A=the expanded surface area,V=the injected saline volume. 2,For≤65 ml group,66-70 ml group,71-75 ml group and≥76ml group,the average expanded area before the expansion maintenance period was 5422.614±402.933mm²,5699.741±294.814mm²,6230.484±194.480mm²,6772.997±395.589mm² respectively,the average expanded area after the expansion maintenance period was 5211.173±351.011mm²,5463.147±311.991mm²,6040.934±137.671mm²,6552.796±316.624mm² respectively,all groups showed statistically significant difference(P＜0.01).3,For 71-77ml group,the percentage of area of the upper one-third of expander,middle one-third of the expander and lower one-third of the expander before the expansion maintenance period was 30.03±1.42%, 34.46±1.85%,35.51±1.65%,respectively,the percentage of area of the upper one-third of expander,middle one-third of the expander and lower one-third of the expander after the expansion maintenance period was 24.8±2.73%,36.12±1.36%,39.08±2.31%respectively,it also showed statistically significant difference(P＜0.01).Conclusion:1.After expansion maintenance period,the expanded area of the whole expander was decreased.For the three equal part of expander,the expanded area percentage of the upper one-third part was decreased,that of the middle one-third and the lower one-third part was decreased,which was another cause which due to the insufficient skin coverage of the auricular cartilage framework.2,As the injected saline volume ranged from 53 to 87ml,the injected saline volume and the expanded surface-area maintained a linear relationship,an effective expansion could be acquired when the injected saline volume reaches to 87ml.