| Background:In recent years,facial contour plastic surgery has shown an increasing trend in plastic surgery in China,and the reduction malarplasty can effectively improve the unaesthetic factors such as the high protrusion of the mid-face contour.At present,we can control the changes of bone tissue clinically,and there is no in-depth study on the changes of soft tissue clinically.Yet one of the most significant variables determining the aesthetic of the postoperative appearance is the alteration in soft tissue,and studying how it change is not only significant for the precise prediction of postoperative appearance,but can also guide the design of preoperative surgical plans,helping surgeons to precisely design the ideal postoperative appearance.In addition,the reduction malarplasty will cause facial droop and further lead to the deepening of nasolabial fold,so it is of great significance to explore the changes of soft tissue at nasolabial fold for the clinical implementation of facial rejuvenation surgery.So this subject was mainly to carry out reduction malarplasty on the patient with high synostosis of zygomatic complex,and their preoperative threedimensional head CT data and facial optical three-dimensional scan data were analyzed by software in a computer,and the mid facial soft tissue changes were analyzed qualitatively and quantitatively to get the rules of postoperative facial soft tissue changes and help surgeons better perform contour surgery preoperative program design,It also provides a certain theoretical basis and clinical guidance for a precise postoperative appearance prediction in the future.Aim:Firstly by establishing a three-dimensional model of the head and face of the patient before and after the reduction malarplasty,qualitative analysis of the postoperative soft tissue changes in the middle face of the patient was conducted to elaborate the region and range of soft tissue changes.Secondly,the change of nasolabial fold was evaluated by grading the severity of nasolabial fold wrinkles before and after surgery.Finally,through qualitative analysis results,quantitative analysis of postoperative changes in the middle facial soft tissue of patients was conducted to explore the relationship between the changes in the middle facial width and the postoperative displacement distance of zygomatic arch point,the displacement of soft tissue landmarks in nasolabial fold and the changes about the middle facial soft tissue thickness.Methods:1.Experiment Ⅰ: the head and face 3D models were reconstructed under a fixed spatial right angle coordinate system by collecting the preoperative and postoperative 3D head CT data and the facial optical 3D scan data of 15 patients who underwent reduction malarplasty with registration fusion in Mimics Medical 21.0 and Einscan Pro software;2.Experiment Ⅱ: Import the preoperative and postoperative 3D model into 3-matic for contrast color scale analysis after registration in Mimics Medical 21.0 to explore the change range of soft tissue after operation,and evaluate the severity of nasolabial fold wrinkles was with WSRS scale and do statistical analysis;3.Experiment Ⅲ: Firstly,the displacement of the zygomatic arch point and the change of the width of the face were measured on the preoperative and postoperative 3D models in Mimics Medical 21.0,and analyze the correlation of its change and calculate its change ratio;Secondly,the landmarks of nasolabial fold were calibrated on the soft tissue three-dimensional model,and the displacement of the marker points in the horizontal,sagittal and vertical directions before and after surgery were measured respectively,and the single-sample t-test was performed,p<0.05 showed that there was statistical difference,so the change of landmark point was analyzed;Finally,the mid-face soft tissue was equally divided into 4 parts in the vertical direction,and the intersection of the horizontal midline and the outer canthus line were the soft tissue landmarks for this part of the experiment.The thickness changes of each landmark before and after surgery were measured in CT and analyzed by paired sample t test.p < 0.05 indicated statistical difference.Results:1.Experiment Ⅰ: Import the head CT and face scan data into Mimics Medical 21.0and Einscan Pro to reconstruct the 3D model of soft and hard tissue,and then use the soft tissue model of CT data as a guide to reconstruct the 3D fusion model of hard tissue and optical 3D scan data and soft tissue;2.Experimental Ⅱ:(1)contrast color order analysis showed that reduction malarplasty decreased the presence of increased soft tissue thickness in some areas postoperatively,of which the more obvious areas were the infraorbital region,paranasal region,parabuccal region of the upper mouth angle,and a few areas of the lower cheek,with a slight increase in soft tissue thickness in the zygomatic region and little change in other facial regions.(2)The results of WSRS showed that WSRS score after surgery(1.733±0.704)was significantly higher than that before surgery(1.267±0.458)(p < 0.05),indicating that the severity of nasolabial fold would increase in some patients after surgery;3.Experiment Ⅲ:(1)The movement of zygomatic arch before and after surgery was strongly correlated with the change of facial width in patients(r = 0.962;p < 0.05),every1 mm of bone tissue displacement would make the overall displacement of the corresponding region about 0.545mm;(2)In the X horizontal direction,NLF2,NLF3 and NLF2’’ on the left and right sides moved(1.349 ± 0.431)mm,(1.329 ± 0.342)mm,(1.057± 0.243)mm,(0.903 ± 0.255)mm,(1.303 ± 0.268)mm and(1.275 ± 0.285)mm to the inside respectively after the operation,and the difference between the left and right sides was statistically significant(p>0.05);In the Y-sagittal direction,NLF1,NLF2,NLF3 and NLF2’’protruded forward(1.564 ± 0.249)mm,(1.316 ± 0.239)mm,(1.829 ± 0.262)mm,(1.411 ± 0.272)mm,(1.479 ± 0.240)mm,(1.295 ± 0.293)mm,(1.990 ± 0.154)mm and(2.141 ± 0.267)mm,respectively,with a statistically significant difference(p<0.05),There was no significant difference between left and right sides(p>0.05);In the vertical direction of Z,NLF2,NLF3 and NLF2’’ on the left and right sides moved down(0.984 ±0.288)mm,(1.044 ± 0.305)mm,(1.247 ± 0.298)mm,(1.237 ± 0.218)mm,(0.500 ± 0.177)mm and(0.575 ± 0.139)mm respectively after operation,the difference was statistically significant(p<0.05),while the difference between the left and right sides was not statistically significant(p>0.05);(3)There was no significant change in the first and second layers of the middle soft tissue,namely the zygomatic body area,after the operation(p>0.05).The thickness of the third and fourth layers of the soft tissue,namely the paraoral area and paranasal area,increased by(1.79 ± 0.48)mm and(1.32 ± 0.83)mm,with statistically significant differences before and after the operation(p<0.05).Conclusion:Reduction malarplasty decreased the amount of soft tissue in the middle of the postoperative period had sagging changes,in which the soft tissue of the parabuccal region and the buccal and paranasal regions were significantly thickened,the soft tissue sagging caused the soft tissue around the nasolabial fold to be compressed,and the landmark points produced a shift,in which NLF2,NLF3 and NLF2’’ protruded inwards and downwards,the NLF1 only protruded forward,while NLF2’ did not change significantly.The movement of zygomatic arch point before and after surgery was strongly correlated with the change of facial width in patients.Every 1mm of bone tissue displacement would result in an overall displacement of about 0.545 mm in the corresponding area.The use of the relationship between the nature and quantity of soft tissue changes will provide relevant theoretical basis for future preoperative design and postoperative prediction,and also provide certain clinical guidance for reduction malarplasty combined with facial rejuvenation surgery... |
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