| [Objective]:(1)Based on the anthropometric method,the maxillofacial region is measured threedimensionally,and the feasible measurement index reflecting the shape and position of the mandible is selected.The evaluation method of mandible reconstruction accuracy is constructed in the virtual environment of computer software.(2)Quantitative analysis of digital guide plate assisted and traditional surgical methods for the accuracy of mandibular defect reconstruction,to compare the accuracy of the two,to explore the role of digital guide plate in the accurate reconstruction of mandibular defects,to provide a theoretical basis for the clinical application of digital guides in accordance with.[Methods]:Study 1:Constructing an evaluation method for the accuracy of mandibular reconstruction.(1)A measurement index for reflecting the morphology of the mandible is selected based on the method of anthropometric head and face measurement.The distance from the condyle to the mandibular angle(ca)indicates the length of the mandibular ascending branch,and the distance from the lower jaw to the ankle(as)indicates the length of the mandibular body,with the condyle-mandibular angle-ankle clip.The angle(cas)reflects the mandibular ascending branch and the body corner,and the angle between the left mandibular body is reflected by the angle of the left mandibular angle-the ankle-the right lower jaw angle(asa).At the same time,the plane of the ear is established as a horizontal reference plane,and the marking points of the mandible are projected on the plane of the ear(the projection points are represented by c1,al,s1),and the marking points of the following jaws are projected to the plane of the ear plane.The distance reflects the positional change in the vertical direction of each point(c-c1,a-a1,s-s1),and the distance between the projection points of the following jaw points on the pupil plane reflects the distance between the points in the horizontal direction.Change(cl-bl,bl-sl).The above evaluation indexes are all related data of the mandibular defect side,and if they are bilateral defects,both sides are defined as the defect side.(2)Obtain the CT data of the patient’s maxillofacial region through PACS system,import the CT data into the digital software to reconstruct the three-dimensional model of the patient’s maxillofacial region,select the mandibular marker site,and obtain the three-dimensional coordinates from the three-dimensional coordinate system generated by the digital software..Re-selected after 1 day interval,5 times in total for 9 days,using statistical software to verify whether the coordinates of the mandibular landmark obtained by this method are highly reproducible.(3)Calculate the coordinates of the mandibular landmark by mathematical formula,obtain the value of the relevant measurement index,and measure it on the patient’s three-dimensional model,and obtain the data of the relevant measurement index.Remeasure after 1 day interval,measure with 9 days.Five times,the statistical software was used to compare the average error of the data obtained by the two methods,and the accuracy of the coordinate value calculation and the direct measurement of the model was compared.Study 2:Evaluation of the accuracy of mandibular defect reconstructionA total of 106 patients with mandibular defects were treated with free iliac musculocutaneous flap in the past three years.The digital osteotomy guide was used to assist 30 patients with mandibular defects.The traditional mandibular defect was used to repair the mandibular defect.Seventy-six patients were enrolled in the study.According to the exclusion criteria,72 patients were enrolled,including 20 in the digitized group,which was set as the experimental group,and 52 in the non-digitized group,which was set as the control group.The experimental group and the control group were simply divided into three categories according to the type of defect.The first type was the defect with the condyle,the second type was the defect and the ascending branch did not reach the condyle.The third type was the defect in the ankle and body..The CT data of 72 patients before and after operation were imported into the digital software by DICOM.The three-dimensional model of the maxillofacial region was generated by three-dimensional reconstruction.The maxillofacial landmarks were selected on the CT images,and the three-dimensional coordinates were obtained.The appeal measurement index was calculated according to the formula.The absolute value of the preoperative and postoperative difference of the appeal measurement index was calculated by combining the formula to calculate the accuracy of the mandibular reconstruction.The smaller the absolute value of the difference is,the smaller the difference between the preoperative and postoperative differences of the appeal measurement index.The gender,age,and defect type variables of the two groups were performed by Fisher’s exact probability method in the form of counting data.All data were expressed as mean and standard deviation.Data from the experimental group and the control group were analyzed by independent sample t test,P<0.05 indicates statistical difference.[Results]:Study one:(1)The corresponding original three-dimensional coordinates of the mandibular landmarks were not statistically significant.All landmarks are highly accurate and repeatable(average error for each coordinate is less than 0.5mm).(2)The correlation distance and angle calculated by the mathematical formula based on the three-dimensional coordinates are more accurate than the numerical values directly measured on the three-dimensional model(the average error of the distance obtained by calculation is less than 1 mm,the angular average error Both are less than 1°;the average error of the distance obtained by direct measurement model is greater than 5mm,and the average angle error is greater than 5°)Study 2:(1)The statistical results of non-experimental factors such as gender,age and defect type of the two groups were P>0.05,no statistical difference,comparable(2)Accuracy evaluation of mandibular reconstruction1)length of the mandible ascending branch:c-a distance;The defect reached the condyle:the experimental group was 4.95±2.79mm,the control group was 15.94± 14.06mm,P=0.030<0.05,and there was statistical difference between the two.The defect reached the ascending branch and did not reach the condyle:the experimental group was 5.66±3.99mm,the control group was 5.12±4.77mm,P=0.746>0.05,there was no statistical difference between the two.The defect was located in the body and ankle:the experimental group was 3.80±4.77mm,the control group was 3.72±4.22mm,P=0.969>0.05,and there was no statistical difference between the two.2)Length of mandibular body length:a-s distanceThe defect reached the condyle:the experimental group was 5.666±4.35mm,the control group was 9.80±9.55mm,P=0.427>0.05,there was no statistical difference between the two.The defect reached the ascending branch and did not reach the condyle:the experimental group was 2.62±1.29mm,the control group was 5.67±5.22mm,P=0.016<0.05,and there was statistical difference between the two.The defect was located in the body and ankle:3.01±3.96mm in the experimental group and 3.85±2.74mm in the control group,P=0.682>0.05.There was no statistical difference between the two groups.3)Mandibular body and mandibular ascending angle:c-a-s angleThe defect reached the condyle:the experimental group was 7.92±3.18°,the control group was 8.32±8.90°,P=0.932>0.05,and there was no statistical difference between the two groups.The defect reached the ascending branch:the experimental group was 5.46±2.85°,the control group was 4.84±3.87°,P=0.639>0.05,and there was no statistical difference between the two groups.The defect was located in the body and ankle:the experimental group was 3.45±2.11°,the control group was 6.74±13.15°,P=0.589>0.05,and there was no statistical difference between the two.4)bilateral mandibular body angle:a-s-a angleThe defect reached the condyle:the experimental group was 3.22±3.21°,the control group was 10.66±11.13°,P=0.227>0.05,and there was no statistical difference between the two groups.The defect reached the ascending branch and did not reach the condyle:the experimental group was 4.72±3.23°,the control group was 4.86±3.80°,P=0.915>0.05,and there was no statistical difference between the two groups.The defect was located in the body and ankle:the experimental group was 2.59±1.20°,the control group was 2.64±2.84°,P=0.910>0.05,and there was no statistical difference between the two.5)vertical height change of the condyle;c-cl distanceThe defect reached the condyle:the experimental group was 3.37±2.09mm,the control group was 16.23±16.71mm,P=0.008<0.05,and there was statistical difference between the two groups.The defect reached the ascending branch and did not reach the condyle:the experimental group was 1.67±0.93mm,the control group was 2.00±1.51mm,P=0.516>0.05,there was no statistical difference between the two.The defect was located in the body and ankle:1.54±1.44mm in the experimental group and 6.52±4.07mm in the control group,P=0.445>0.05,there was no statistical difference between the two.6)Vertical height change of the mandibular angle;a-al distanceThe defect reached the condyle:the experimental group was 11.03±6.78mm,the control group was 7.13±5.17mm,P=0.252>0.05,there was no statistical difference between the two.The defect reached the ascending branch:the experimental group was 6.24±3.79mm,the control group was 5.06±4.60mm,P=0.470>0.05,there was no statistical difference between the two.The defect was located in the body and ankle:3.01±3.96mm in the experimental group and 3.85±2.47mm in the control group,P=0.682>0.05.There was no statistical difference between the two groups.7)vertical height change of the ankle;s-s1 distanceThe defect reached the condyle:the experimental group was 2.82±0.99mm,the control group was 5.26±4.08mm,P=0.098>0.05,there was no statistical difference between the two.The defect reached the ascending branch:the experimental group was 4.90±3.71mm,the control group was 6.41±7.26mm,P=0.437>0.05,there was no statistical difference between the two.The defect was located in the body and ankle:the experimental group was 3.17±1.51mm,the control group was 3.24±3.09mm,P=0.767>0.05,and there was no statistical difference between the two.8)Horizontal distance of the mandible ascending branch:cl-alThe defect reached the condyle:the experimental group was 5.10±2.13mm,the control group was 5.15±3.96mm,P=0.985>0.05,there was no statistical difference between the two.The defect reached the ascending branch and did not reach the condyle:the experimental group was 5.55±3.91mm,the control group was 5.02±4.67mm,P=0.746>0.05,there was no statistical difference between the two.The defect was located in the body and ankle:the experimental group was 3.45±4.77mm,the control group was 3.65±3.02mm,P=0.849>0.05,there was no statistical difference between the two.9)Horizontal distance of the mandible body:al-slThe defect reached the condyle:the experimental group was 5.36±3.78mm,the control group was 8.80±8.25mm,P=0.413>0.05,there was no statistical difference between the two.The defect reached the ascending branch:the experimental group was 2.32±1.18mm,the control group was 5.47±5.01mm,P=0.010<0.05,and there was statistical difference between the two groups.The defect was located in the body and ankle:the experimental group was 3.56±3.60mm,the control group was 2.85±2.36mm,P=0.598>0.05,there was no statistical difference between the two.[Conclution]:1.Using the surgical navigation software to trace the hard tissue landmarks of the maxillofacial region and establish its three-dimensional coordinates.The spatial distance and angle of the hard tissue landmarks of the mandible can be measured threedimensionally to reflect the shape and position of the mandible.2.Digital osteotomy guide plate assists mandibular defect reconstruction with higher accuracy in recovery from condylar height and mandibular angle than traditional surgical methods. |
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