Digital Technique Applied In Anatomical Study Of Zygomaticomaxillary Complex And Measurement Of Orbital Volume

BackgroundZygomaticomaxillary complex(zygomatic complex, zygomaticoorbital complex, etc.), at the middle of maxillofacial region, formed by anatomical structures such as zygomatic bone, zygomatic arch and maxilla, which adjacent to frontal bone, temporal bone, eye socket, preserves the width and anterior process of the midfacial part and plays an important part in facial appearance and function.Because of the special position of anatomical position, morbidity of the zygomaticomaxillary complex fracture undergone a ratio of18.44%in maxillofacial region fracture, second to mandibular fracture. When stroked by external force, fracture frequently involved the neighbouring bone, and occurred complications leading to appearance and function defect, such as collapse deformity of face, limitation of mouth opening, enophthalmos, diplopia. Therefor, accurate restoration of bone fracture sections ensured that appearance and masticatory function would be recovered. But as the translocation of fracture bone sections of zygomaticomaxillary complex were towards three dimensional in clinical treatment, traditional two dimensional CT radiographic images were difficult helped to judge the displacement orientation and extent of fracture. And there was no restoring standard as referenced position about zygomaticomaxillary complex normal three-dimension anatomy. So there were discrepancy of therapy methods and caused corresponding complications.As far as today,rather comprehensive studies on zygomaticomaxillary complex three-dimension anatomy has been rarely discussed at home and abroad. In clinical practice it has been lack of research about how to fix position of fracture translocation extent precisely or estimate deformity by trauma preoperation, as well as how to mensurable evaluate the quality fracture restoration objectively postoperation.Cephalometrics, first used in1931, has become the one of important tools to analysis and diagnosis maxillofacial deformity to oral and maxillofacial surgery and orthodontics field. As the traditional cephalometrics developed, experienced from counterdraw measure by hand to managing and analysis by computer technology, it would lose a large number of anatomical structure massage and influence accurately therapy because of the factors like radiate requirement which resulting multiple measuring error yet. Following computer software aided reconstruction and measuring technique and high-precision lightspeed CT used, it provided advanced mathods and speedy tools for measuring analysis of zygomaticomaxillary complex three-dimension anatomy and personalized treatment.ObjectiveIn this study, we would compared the measure results of direct anthropometry with the3D CT image anthropometry combined computer software aided reconstruction and measuring technique of three-dimension CT image measurement. It would provide rather comprehensive and valuable reference data, and help to quantitative diagnose the change of intraorbital volume after zygomaticomaxillary complex fracture by digitalized measuring technique. In part two of this study,made use of the Simplantll.04analytic software to calibrate the intact and traumatized orbital volume after zygomaticomaxillary complex fracture.The measurement of orbital volume can help operator to make operation plan and restore original orbital volume accurated, to avoid the development of endophthalmos. The method, which is accurate, convenient and speedily for clinical therapy, could be widely used in the personalized treatment of zygomaticomaxillary complex fracture.Materials and MethodsPartⅠDigital measuring technique applied in anatomical study of zygomaticomaxillary complex1.Selected specimens:Selected the twenty health adult cadaveric dry skull specimens from the Department of Anatomy, Southern Medical University. Specimens requirements that there were no obvious Craniomaxillofacial malformation, trauma and operation wound.All anatomic landmarks were clear and no abrasion.2. Direct anthropometry:Made the every landmarks in skull specimens,according to the selected measurements,used the caliper to proceed the direct anthropometry,and records the results.3. The scanning method for specimen:Using64-slice CT scan,the scan parameters: slice thickness0.6mm, tube current of200mA, the voltage120kV.The specimen fixed to the CT scanner on heads-up,according to the cross positioning beam, rbitomeatal plane perpendicularity to horizontal plane, time base parallel to orbitomeatal plane(fig1-1,1-2).Scan range from calvaria to alveoli dentales maxillae,preserved the images to DICOM format.4.3D CT image anthropometry:The obtained images were inputted into three-dimensional model reconstruction sofewere Simplantll.04to renconstruct the model.Reproduce the form of bone on craniomaxillofacial. According to the measurement contents to proceed the3D CT image anthropometry,the sofewere could automatic generation the results of the distance measurement.5. Data processing:All of measurements finished by one observer.Measurements, obtained with both direct anthropometry and3D CT image anthropometry analysis, were taken twice for each subject, in sessions conducted1week apart (T1and T2) to reduce the potential for memory bias.6. Statistics analysis:Used the statistical analysis software SPSS13.0to analysis the results of measurement. Paired t-test was used to compare the accuracy and precision of direct anthropometry and3D CT image anthropometry. Differences were considered significant at P<0.05.Part ⅡMeasurement of orbital volume in zygomaticomaxillary complex fractures based on digital measuring technique1.The criteria of selection and inclusion clinical case:To collected18patients with the zygomaticomaxillary complex fractures and endophthalmos was treated in Nan Fang Hospital at Oct.2008-Oct.2010.The type of injure for patients:8patients were orbital fractures,7were orbital fractures combine maxillary fractures,3were naso-orbito-ethmoid fracture.2.The criteria of selected clinical case:(1) One side zygomaticomaxillary complex fractures, opposite side could be control group;(2) Endophthalmos length≥2mm, eyeball was completed and no injury, visual acuity was no obvious decline.3. Three-dimensional model reconstruction of Orbit:Using64-slice three-dimensional spiral CT to scan the18patients of zygomaticomaxillary complex fractures.The patients kept the supine position and with the headlock. According to the cross positioning beam, rbitomeatal plane perpendicularity to horizontal plane, time base parallel to orbitomeatal plane, slice thickness1mm. Preserved the images to DICOM format, the obtained images were inputted into three-dimensional model reconstruction sofewere Simplant11.04to renconstruct the model. Scan range was up to supraorbital arch,down to infraorbital border, The posterior border to the anterior border of foramen opticum, anterior border abreast margo orbitalis.Finished tracing, the sofewere Simplantl1.04will automatic generation the three-dimensional reconstruction model.4.Calculated orbital volume:Finished tracing of CT image date, the sofewere Simplant11.04will automatic generation the three-dimensional reconstruction model and calculated the bilateral orbital volume of patients.5.Statistics analysis:Used sofewere Simplantl1.04to calculated the bilateral orbital volume of18patients with the zygomaticomaxillary complex fractures and endophthalmos.Separately calculated the the contralateral side of the orbital volume and healthyside orbital volume of9male patients and9female patients.Used the statistical analysis software SPSS13.0to analysis the results of measurement. Paired t-test and two-sample t-test was used to analysis respectively. Differences were considered significant at P<0.05.Results1.This study successful established the zygomaticomaxillary biomechanical model by using the precise CT scan the three-dimensional reconstruction software Simplantl1.04. After tested and verified the results of the experiment,The model have geometric similarity, and vivid shape.2.The results of measurement(T1and T2) there was no statistical difference of direct anthropometry(P>0.05), except oz-mp(t=-2.741,P=0.013, P<0.05); 3.the result of measurement(Tl and T2) there was no statistical difference of3D CT image anthropometry(P>0.05),except n-pr (t=-2.276, P=0.035, P<0.05).In this study it considered as,the results of two methods has more accurary, The results were reliable.4.The results of measurement of direct anthropometry and3D CT image anthropometry there was no statistical difference(P>0.05), it considered that there is more precision between direct anthropometry and3D CT image anthropometry.5. The measurement of height of contour on zygoma:We could concluded that height of contour on zygoma located at the midpoint of zygoma in horizontal direction,and at the downwards1.5-1.8cm of middle and outside1/3juncture and partial outside infraorbital border; namely,the height of contour on zygoma is located at middle and below1/3juncture of zygoma.6.The results of Part II:Traumatized orbital volume enlarged in all patients, with a mean of (1.831±0.749) cm3compared with the opposite intact orbit, Significant differences in orbital volumes existed intact and traumatized (t=-10.376,P=0.000). A mean of male intact orbit volume is (28.496±1.154)cm3, female intact orbit volume is (23.567±1.308) cm3. Significant differences in orbital volumes existed male and female (t=8.478, P=0.000)Conclusions1. Height of contour on zygoma located at the midpoint of zygoma in horizontal direction,and at the downwards1.5-1.8cm of middle and outside1/3juncture and partial outside infraorbital border; namely.the height of contour on zygoma is located at middle and below1/3juncture of zygoma.It could be the reference of finding the most metal dots of Zygoma in reduction.of zygomaticomaxillary complex fractures.2. In this study the cranial and maxillofacial three-dimensional reconstruction models that scanned by three-dimensional Lightspeed VCT and designed by Simplant11.04software aided showed the behavior of admirable geometrical similarity. It could not only display the three-dimensional anatomical structure of zygomaticomaxillary complex, but also transform and spin in different shaft sides. Statistics inspection provided evidence that the measuring results used three-dimensional CT image measurement of Simplant software were accurate and reliability. In clinical work, this research results could be used to measure the part, boundary and fracture section displacement or distance of zygomaticomaxillary complex fractures. This method can be available to quantitative study on anatomy and anthropology trend. And for personalized restoring of fracture trauma and defect in the field of oral and maxillofacial surgery, orthodontics and deformity repairing in orthognathic surgery, it provided a solid foundation for further applications.3. In the second part of this study, we used three-dimensional reconstruction and computer software aided measuring technique to measure the change of orbit volume after zygomaticomaxillary complex fracture.After experimental measurements and study concluded that:zygomaticomaxillary complex fractures leaded to orbital volume increased,and relationship between the Endophthalmos,patients with different gender had different alteration of orbital volume. It could help the surgeons according to volume change of orbit to restore and reset bulbus oculis,clinical treatment for different patients need to better tailored repair mode. So this skill could improve on the efficacy of eye socket restoring and bulbus oculis restoring.