Application of rapid prototyping head model in treatment of zygomatic complex fractures
http://www.100md.com
《中华医药杂志》英文版 2006年第3期
Correspondence to PENG Ling-ling,the Affiliated Hospital of Xuzhou Medical College,Xuzhou 221002,Jiangsu Province,China
Tel:+86-516-85802022
[Abstract]ObjectiveTo discuss the application of rapid prototyping techniques in the diagnosis and treatment of zygomatic complex(ZMC) fractures.MethodsFrom 2002 to 2004, a total of 9 patients in our ward suffered from severe ZMC fractures were taken three-dimensional CT examination before operation .The data of the CT images were transformed into an usual formal file which can be read by a rapid prototyping machine with a software called MIMICS. According to the data of the patient, the head model which is similar to the bones of the patient in shape was manufactured within about twenty hours. All the patients had a general anesthetics and an operation of open reduction and rigid fixation with the guidance of rapid prototyping model of head which were made using LOM techniques or SLA techniques. Using head model, we made supplementary diagnosis and performed model surgery such as osteotomies, reduction and fixation. Sometimes primary shaping of the titanium plate can cut the time of operation. After operation, all the patient take a computerized tomography and related software for CT metrical analysis which was established by ourselves was used to observe the remained displacement of the fractured malar .ResultsAll the patients using rapid prototyping techniques got a complete same diagnosis during operation with diagnosis before operation. The operation time is cut apparently compared with others who had not got a head model. A classification was proposed based on the deformities of zygomatic fractures. All the diagnosis before and in operation were of the same completely and effect of the treatment is excellent. All the patients were satisfied with the recuperation of their outlook of face. ConclusionsThree-dimensional head model made by the rapid prototyping techniques can confirm the diagnosis further before operation. Model surgery on it can provide exact data for surgery approaches, orientations and distance of reduction. As a result, time of operation was decreased. But the clinical application of it is still circumscribed by long time of preparation for operation and its high cost of making the model.
[Key words]zygomatic complex fracture;tomography,computed;rapid prototyping head model
INTRODUCTION
Traditional manufacture industry made modules with a method of eliminated materials including abrasion, cutting, chop, drill etc. With the development of rapid prototyping techniques, the pilling materials method based on computer techniques has gradually substituted the role of traditional manufacture techniques in an expanding field, and will become the mainstream in trend.
Model techniques and model surgery are the important method in medical research. Model surgery can not only make the surgeon learn the process of the operation directly, but also provide the accuracy data of the movement of the fractured bone.
MATERIALS AND METHODS
Clinical Data
Nine patients suffered from zygomatic complex fractures were selected in the research. They are aged from 31 years to 71 years,7 males and 2 females. Eight were injured in traffic accidents and one during working.
Three-Dimensional Head Model Made by Rapid Prototyping Techniques
Every patients had a computed tomography(CT) examination before operation. The two dimensional data collected by CT were converted into the three-dimensional stereo images of the skull with a software called MIMICS (Materialise NV, Belgium). Then the stereo
images were cut into 1 mm slices before transmission to the rapid prototyping machine (the United States of America). Controlling by the computer, frequency CO2 laser bean agglomerates in each slice the powder of polystyrene (engineering plastic, diameter of each grain less than 0.1 mm) in selected area. The making of each head model lasted about 20 hours. Then spray epoxy ethane on the model surface before irradiation by ultraviolet ray 40 minutes for solidification.
Moulding Board for Operation during Model Surgery (Figure 1 to Figure 3)
Renew the diagnosis of minute fractures. Analysing the displacement, fractures in the orbital wall and classification of defects. Simulate the cutting of the bone on the head model and the reductions based on the predict data to get a symmetry facial figure. Bend the titanium plate on the head model for use in operation after pilling the whole figure of the zygomatic bone with red wax. Then take off the entire red wax and make out the self-coagulated resin module plate from it. The module plate must be sterilized for use of surgery. If there are some defects in the orbital wall, prepare the implant materials such as Medpore or titanium meshwork for later use after sterilization.
Analysis of the Effects
Every patient had a three-dimensional computed tomography examination and photos at a face upward position to compare these images with the counterpart before operation. The effect of the CT measurement system and the application of the rapid prototyping head model were evaluated. The accuracy of the prediction was evaluated by comparing the real result after operation with the data which had been predicted before operation.
RESULTS
During operation, the bone scar was cut according to the model and the fractured bone was moved to the right position by prying and dialing. Reduction of the zygomatic bone, place of the titanium plate and drilling the hole have index separately. The process was simple and apparent. The profile of the face after operation was symmetry and harmony.
Eight of nine patients were indicated by CT after operation to be in the complete reduction and have a three-dimensional symmetrical appearance. In 3 to 12 months of follow-up, all patients had a full mouth open range. The rehabilitation of masticatory function was very good and no complications were found after operation. The patients were satisfied with the effect of the treatment.
One patient suffered from a complex comminuted fracture got a symmetry appearance because of the asymmetry incrassation although the reduction of the fracture was not good. For one patient, we simulated the original images of the zygomatic bone before the trauma of the injured lateral with the computed aided reverse engineering and the CT data of the healthy lateral. Then we got the rapid prototyping head model of his normal head before the trauma. On this dummy head model, we bent the titanium plate and got a good result at last (Figure 4~Figure 14).
Figure 1 LOM technique Figure 2 Agglomeration by laser Figure 3 Photosensitive resin
DISCUSSION
In 1985 Brix grinded the first three-dimensional imitating head model of the patient in the world with computer-aided design (CAD), computer-aided manufacture (CAM) techniques and a grinding machine after reconstruction of the three-dimensional CT image.
After that, the agglomeration by laser controlling by the computer techniques was performed in the manufacture of the three-dimensional head model, which improved the practicability and the exactness of the model greatly. This technique could imitate the minute structure and the hole in the model, and thus the models have more third dimension[1].
The rapid prototyping (RP) technique is a floorboard of a group of techniques developed recently based on CAD module to produce the samples and accessories rapidly. It integrated CAD techniques, numerical control techniques, laser techniques, material techniques etc. RP technique is an important part of the modern techniques as well.
The common types of rapid prototyping are [2]: selecting solidification of liquid photosensitive polymer (SLA); selecting incision the thin materials (layer object manufacture); melting the selected threadlike thing (FDM); sintering the selected powder materials (selecting layer sinter).
The rapid prototyping technique was presented in the field of spaceflight industry in 1986 at first[3].Its prominent character is able to make out all kinds of complex accessories within short time. The technique was applied soon to the industry of motors, family electronics, mould, electronics hardware and other industry branches. The rapid prototyping technique was firstly used to the medical field in early 1990 s[4] and mainly based on the development of the high definition examination techniques such as computed tomography or magnetic resonance(MR) imaging.
The basic step of RP technique is transferring the image data information from CT or MR layer by layer into the command files which can control the digital controlling lathe machine to process the three-dimensional model layer by layer. In early time of this technique, the resource of the image information is from the CT film with a scanner machine. Special software transfers the data from the scanner. So the precision of the model is mainly determined by the precision of the CT films.
With the development of the spiral CT and the volume rendering method, the original image data can be input into the computer directly. The original data can be fined by inserting values with mathematic method. So, the precision of the products are improved greatly.
In medical field RP technique was firstly applied into surgery such as orthopaedics, oral and maxillofacial surgery, plastics and reconstruction surgery. With RP techniques, we can produce the wholly biomodel imitating three-dimensional structures both inner and outside of it. The line error of this model is less than 0.05 mm and the total error is not more than 0.1%[5]. Such precision can meet the need of surgeons completely. Surgeons are not hindered by the difficulty of getting anatomical samples and not worried about the moral and ethic problems.
In face of the rapid development of recent operation styles and the more complexity of the lesion, surgeons can acquaint themselves more directly with the conditions of the operated region with the help of rapid prototyping model of the anatomical structure. They can make the operation plan more reasonable for the most intricate patients after discussion on the stereo model[6].
Durso[7]used rapid prototyping model for diagnosis before operation. He designed the treatment plan and made explanation to the patients after CT examination on 45 patients suffered from lesion in skull base or oral and maxillofacial regions. The result indicated that RP head models can improve the precision of the diagnosis before operation for 95.23% patients.
The biomodel by rapid prototyping techniques now became a powerful tool for the research in biomechanics. Vloeberghs[8] made out the model of heart cavity from MR imaging with this technique to study the characteristics of the blood dynamics in body cavities. Kelly[9]made the model of nasal cavity from CT images and studied the air currents in the model to know the sequence of the magnitude of streams in different region of the nasal cavity. He got the important knowledge about principals on the temperature of airflow and olfaction sense regulated by nasal cavity. Other researchers made out the biomodel of heart valve, brain blood vessels and heart blood vessels to study the relationship between anatomical structure and blood dynamics which is helpful to know the engendering of the aneurism.
With the help of three-dimensional imitating head model,surgeons can acquaint themselves precisely with the quality, degree and range of the deformities in stereo structure of the cranio-maxillofacial bone. They can design the treatment plan according to the characteristics of each patient. We use the rapid prototyping technique to make the three-dimensional imitating head model of the patients suffered from zygomatic complex fracture. We can learn the stereo information of the abnormalities and make self-agglomerating plastic module plate for late use in operation. In model surgery, we can bend the small pure titanium plate or titanium meshwork after reduction. We can use the mark pole method to move the bone fragment quantitatively. The implant materials such as Medpore can be prepared by shaping for late use in operations on the patients whose defect in orbital wall need to be repaired. And thus the operation time is shortened.
The patient and their families are sometimes difficulty to understand the disease and the operation plan for lacking of medical knowledge. Simple abstract explanation in theory may cost a lot of time of the surgeon and the effects are not good. We indicated the fracture and its relationship with adjacent organs by directly showing the head model to the patients. The results are good.
We also find that big titanium meshwork sometimes is difficult to put in because of the restraint by incision. The model is low in hardness and can break into pieces when violent knocks on it.
The application of the head model in an extensive range is limited by the two or three days of making it. The cost is too much to the common people now. However, we believe that with the development of modern techniques the information transmission between the department of radiology in hospital and the head model company will be much easier. The images from CT or MR can be transmitted directly to the company of titanium plate or the company of Medpore. The individual titanium plate (meshwork) or Medpore which can be used in operation without any shaping will be in practice and improve the clinical effect of the treatment greatly.
REFERENCES
1. 段少银，康江河，黄锡恩，等.螺旋CT三维容积重建的临床应用.中国临床医学影像杂志，2000,11(5):335-338.
2. McFarland EG, Brink JA, Loh J, et al. Visualization of colorectal polyps with spiral CT colography: evaluation of processing parameters with perspective volume rendering.Radiology, 1997,205(3):701-707.
3. Durso PS, Barker TM, Earwaker WJ, et al. Stereolithographic biomodelling in cranio-maxillofacial surgery: a prospective trial.J Craniomaxilofac Surg, 1999,27(1):30-37.
4. Vloeberghs M, Hatfied F, Daemi F, et al. Soft tissue rapid prototyping in neurosurgery. Comput Aided Surg, 1998, 3(2):95-97.
5. Anderson JR, Chiu DT, Jackman RJ, et al. Fabrication of topologically complex three-dimensional microfluidic systems in PDMS by rapid prototyping. Anal-Chem,2000,72(14):3158-3164.
6. Anderson JR, Chiu DT, Jackman RJ, et al. Fabrication of topologically complex three dimensional microfluidic systems in PDMS by rapid prototyping. Anal Chem,2000,72(14):3158-3164.
7. Durso PS, Thompson RG, Atkinson RL, et al. Cerebrovascular biomodelling: a technical note. Surg-Neurol,1999,52(5):490-500.
8. Binder TM, Moertl D, Mundigler G, et al. Stereo-lithographic biomodeling manufactured using a computerized tomography angiogram as a mold to create tangible hard copies of cardiac structures from echocardiographic data: in vitro and in vivo validation. J Am Coll Cardiol,2000,35(1):230-237.
9. Kelly JT, Prasad AK , Wexler AS. Detailed flow patterns in the nasal cavity. J Appl Physiol,2000,89(1):323-337.
1 Department of Oral and Maxillofacial Surgery, the Ninth Affiliated Hospital of Shanghai Second Medical University,Shanghai 200011,China
2 Department of Stomatology, the Affiliated Hospital of Xuzhou Medical College,Xuzhou 221002,Jiangsu Province,China
(Editor Emilia)(SUN Yu-hua1，2，TANG You-sh)
Tel:+86-516-85802022
[Abstract]ObjectiveTo discuss the application of rapid prototyping techniques in the diagnosis and treatment of zygomatic complex(ZMC) fractures.MethodsFrom 2002 to 2004, a total of 9 patients in our ward suffered from severe ZMC fractures were taken three-dimensional CT examination before operation .The data of the CT images were transformed into an usual formal file which can be read by a rapid prototyping machine with a software called MIMICS. According to the data of the patient, the head model which is similar to the bones of the patient in shape was manufactured within about twenty hours. All the patients had a general anesthetics and an operation of open reduction and rigid fixation with the guidance of rapid prototyping model of head which were made using LOM techniques or SLA techniques. Using head model, we made supplementary diagnosis and performed model surgery such as osteotomies, reduction and fixation. Sometimes primary shaping of the titanium plate can cut the time of operation. After operation, all the patient take a computerized tomography and related software for CT metrical analysis which was established by ourselves was used to observe the remained displacement of the fractured malar .ResultsAll the patients using rapid prototyping techniques got a complete same diagnosis during operation with diagnosis before operation. The operation time is cut apparently compared with others who had not got a head model. A classification was proposed based on the deformities of zygomatic fractures. All the diagnosis before and in operation were of the same completely and effect of the treatment is excellent. All the patients were satisfied with the recuperation of their outlook of face. ConclusionsThree-dimensional head model made by the rapid prototyping techniques can confirm the diagnosis further before operation. Model surgery on it can provide exact data for surgery approaches, orientations and distance of reduction. As a result, time of operation was decreased. But the clinical application of it is still circumscribed by long time of preparation for operation and its high cost of making the model.
[Key words]zygomatic complex fracture;tomography,computed;rapid prototyping head model
INTRODUCTION
Traditional manufacture industry made modules with a method of eliminated materials including abrasion, cutting, chop, drill etc. With the development of rapid prototyping techniques, the pilling materials method based on computer techniques has gradually substituted the role of traditional manufacture techniques in an expanding field, and will become the mainstream in trend.
Model techniques and model surgery are the important method in medical research. Model surgery can not only make the surgeon learn the process of the operation directly, but also provide the accuracy data of the movement of the fractured bone.
MATERIALS AND METHODS
Clinical Data
Nine patients suffered from zygomatic complex fractures were selected in the research. They are aged from 31 years to 71 years,7 males and 2 females. Eight were injured in traffic accidents and one during working.
Three-Dimensional Head Model Made by Rapid Prototyping Techniques
Every patients had a computed tomography(CT) examination before operation. The two dimensional data collected by CT were converted into the three-dimensional stereo images of the skull with a software called MIMICS (Materialise NV, Belgium). Then the stereo
images were cut into 1 mm slices before transmission to the rapid prototyping machine (the United States of America). Controlling by the computer, frequency CO2 laser bean agglomerates in each slice the powder of polystyrene (engineering plastic, diameter of each grain less than 0.1 mm) in selected area. The making of each head model lasted about 20 hours. Then spray epoxy ethane on the model surface before irradiation by ultraviolet ray 40 minutes for solidification.
Moulding Board for Operation during Model Surgery (Figure 1 to Figure 3)
Renew the diagnosis of minute fractures. Analysing the displacement, fractures in the orbital wall and classification of defects. Simulate the cutting of the bone on the head model and the reductions based on the predict data to get a symmetry facial figure. Bend the titanium plate on the head model for use in operation after pilling the whole figure of the zygomatic bone with red wax. Then take off the entire red wax and make out the self-coagulated resin module plate from it. The module plate must be sterilized for use of surgery. If there are some defects in the orbital wall, prepare the implant materials such as Medpore or titanium meshwork for later use after sterilization.
Analysis of the Effects
Every patient had a three-dimensional computed tomography examination and photos at a face upward position to compare these images with the counterpart before operation. The effect of the CT measurement system and the application of the rapid prototyping head model were evaluated. The accuracy of the prediction was evaluated by comparing the real result after operation with the data which had been predicted before operation.
RESULTS
During operation, the bone scar was cut according to the model and the fractured bone was moved to the right position by prying and dialing. Reduction of the zygomatic bone, place of the titanium plate and drilling the hole have index separately. The process was simple and apparent. The profile of the face after operation was symmetry and harmony.
Eight of nine patients were indicated by CT after operation to be in the complete reduction and have a three-dimensional symmetrical appearance. In 3 to 12 months of follow-up, all patients had a full mouth open range. The rehabilitation of masticatory function was very good and no complications were found after operation. The patients were satisfied with the effect of the treatment.
One patient suffered from a complex comminuted fracture got a symmetry appearance because of the asymmetry incrassation although the reduction of the fracture was not good. For one patient, we simulated the original images of the zygomatic bone before the trauma of the injured lateral with the computed aided reverse engineering and the CT data of the healthy lateral. Then we got the rapid prototyping head model of his normal head before the trauma. On this dummy head model, we bent the titanium plate and got a good result at last (Figure 4~Figure 14).
Figure 1 LOM technique Figure 2 Agglomeration by laser Figure 3 Photosensitive resin
DISCUSSION
In 1985 Brix grinded the first three-dimensional imitating head model of the patient in the world with computer-aided design (CAD), computer-aided manufacture (CAM) techniques and a grinding machine after reconstruction of the three-dimensional CT image.
After that, the agglomeration by laser controlling by the computer techniques was performed in the manufacture of the three-dimensional head model, which improved the practicability and the exactness of the model greatly. This technique could imitate the minute structure and the hole in the model, and thus the models have more third dimension[1].
The rapid prototyping (RP) technique is a floorboard of a group of techniques developed recently based on CAD module to produce the samples and accessories rapidly. It integrated CAD techniques, numerical control techniques, laser techniques, material techniques etc. RP technique is an important part of the modern techniques as well.
The common types of rapid prototyping are [2]: selecting solidification of liquid photosensitive polymer (SLA); selecting incision the thin materials (layer object manufacture); melting the selected threadlike thing (FDM); sintering the selected powder materials (selecting layer sinter).
The rapid prototyping technique was presented in the field of spaceflight industry in 1986 at first[3].Its prominent character is able to make out all kinds of complex accessories within short time. The technique was applied soon to the industry of motors, family electronics, mould, electronics hardware and other industry branches. The rapid prototyping technique was firstly used to the medical field in early 1990 s[4] and mainly based on the development of the high definition examination techniques such as computed tomography or magnetic resonance(MR) imaging.
The basic step of RP technique is transferring the image data information from CT or MR layer by layer into the command files which can control the digital controlling lathe machine to process the three-dimensional model layer by layer. In early time of this technique, the resource of the image information is from the CT film with a scanner machine. Special software transfers the data from the scanner. So the precision of the model is mainly determined by the precision of the CT films.
With the development of the spiral CT and the volume rendering method, the original image data can be input into the computer directly. The original data can be fined by inserting values with mathematic method. So, the precision of the products are improved greatly.
In medical field RP technique was firstly applied into surgery such as orthopaedics, oral and maxillofacial surgery, plastics and reconstruction surgery. With RP techniques, we can produce the wholly biomodel imitating three-dimensional structures both inner and outside of it. The line error of this model is less than 0.05 mm and the total error is not more than 0.1%[5]. Such precision can meet the need of surgeons completely. Surgeons are not hindered by the difficulty of getting anatomical samples and not worried about the moral and ethic problems.
In face of the rapid development of recent operation styles and the more complexity of the lesion, surgeons can acquaint themselves more directly with the conditions of the operated region with the help of rapid prototyping model of the anatomical structure. They can make the operation plan more reasonable for the most intricate patients after discussion on the stereo model[6].
Durso[7]used rapid prototyping model for diagnosis before operation. He designed the treatment plan and made explanation to the patients after CT examination on 45 patients suffered from lesion in skull base or oral and maxillofacial regions. The result indicated that RP head models can improve the precision of the diagnosis before operation for 95.23% patients.
The biomodel by rapid prototyping techniques now became a powerful tool for the research in biomechanics. Vloeberghs[8] made out the model of heart cavity from MR imaging with this technique to study the characteristics of the blood dynamics in body cavities. Kelly[9]made the model of nasal cavity from CT images and studied the air currents in the model to know the sequence of the magnitude of streams in different region of the nasal cavity. He got the important knowledge about principals on the temperature of airflow and olfaction sense regulated by nasal cavity. Other researchers made out the biomodel of heart valve, brain blood vessels and heart blood vessels to study the relationship between anatomical structure and blood dynamics which is helpful to know the engendering of the aneurism.
With the help of three-dimensional imitating head model,surgeons can acquaint themselves precisely with the quality, degree and range of the deformities in stereo structure of the cranio-maxillofacial bone. They can design the treatment plan according to the characteristics of each patient. We use the rapid prototyping technique to make the three-dimensional imitating head model of the patients suffered from zygomatic complex fracture. We can learn the stereo information of the abnormalities and make self-agglomerating plastic module plate for late use in operation. In model surgery, we can bend the small pure titanium plate or titanium meshwork after reduction. We can use the mark pole method to move the bone fragment quantitatively. The implant materials such as Medpore can be prepared by shaping for late use in operations on the patients whose defect in orbital wall need to be repaired. And thus the operation time is shortened.
The patient and their families are sometimes difficulty to understand the disease and the operation plan for lacking of medical knowledge. Simple abstract explanation in theory may cost a lot of time of the surgeon and the effects are not good. We indicated the fracture and its relationship with adjacent organs by directly showing the head model to the patients. The results are good.
We also find that big titanium meshwork sometimes is difficult to put in because of the restraint by incision. The model is low in hardness and can break into pieces when violent knocks on it.
The application of the head model in an extensive range is limited by the two or three days of making it. The cost is too much to the common people now. However, we believe that with the development of modern techniques the information transmission between the department of radiology in hospital and the head model company will be much easier. The images from CT or MR can be transmitted directly to the company of titanium plate or the company of Medpore. The individual titanium plate (meshwork) or Medpore which can be used in operation without any shaping will be in practice and improve the clinical effect of the treatment greatly.
REFERENCES
1. 段少银，康江河，黄锡恩，等.螺旋CT三维容积重建的临床应用.中国临床医学影像杂志，2000,11(5):335-338.
2. McFarland EG, Brink JA, Loh J, et al. Visualization of colorectal polyps with spiral CT colography: evaluation of processing parameters with perspective volume rendering.Radiology, 1997,205(3):701-707.
3. Durso PS, Barker TM, Earwaker WJ, et al. Stereolithographic biomodelling in cranio-maxillofacial surgery: a prospective trial.J Craniomaxilofac Surg, 1999,27(1):30-37.
4. Vloeberghs M, Hatfied F, Daemi F, et al. Soft tissue rapid prototyping in neurosurgery. Comput Aided Surg, 1998, 3(2):95-97.
5. Anderson JR, Chiu DT, Jackman RJ, et al. Fabrication of topologically complex three-dimensional microfluidic systems in PDMS by rapid prototyping. Anal-Chem,2000,72(14):3158-3164.
6. Anderson JR, Chiu DT, Jackman RJ, et al. Fabrication of topologically complex three dimensional microfluidic systems in PDMS by rapid prototyping. Anal Chem,2000,72(14):3158-3164.
7. Durso PS, Thompson RG, Atkinson RL, et al. Cerebrovascular biomodelling: a technical note. Surg-Neurol,1999,52(5):490-500.
8. Binder TM, Moertl D, Mundigler G, et al. Stereo-lithographic biomodeling manufactured using a computerized tomography angiogram as a mold to create tangible hard copies of cardiac structures from echocardiographic data: in vitro and in vivo validation. J Am Coll Cardiol,2000,35(1):230-237.
9. Kelly JT, Prasad AK , Wexler AS. Detailed flow patterns in the nasal cavity. J Appl Physiol,2000,89(1):323-337.
1 Department of Oral and Maxillofacial Surgery, the Ninth Affiliated Hospital of Shanghai Second Medical University,Shanghai 200011,China
2 Department of Stomatology, the Affiliated Hospital of Xuzhou Medical College,Xuzhou 221002,Jiangsu Province,China
(Editor Emilia)(SUN Yu-hua1，2，TANG You-sh)