【Abstract】 Objective To evaluate the feasibility and effectiveness of reconstruction of mandibular bone defects using three-dimensional skull model and individualized titanium prosthetics from computer assisted design. Methods Between July 2002 and November 2009, 9 patients with mandibular defects accepted restorative operation using individualized bone prosthetics. Among 9 cases, 4 were male and 5 were female, aged 19-55 years. The causes of mandibulectomy were benign lesions in 8 patients and carcinoma of gingival in 1 patient. Mandibular defects exceeded midline in 2 cases, involved condylar in 4 cases, and was limited in one side without involvement of temporo-mandibular joint in 3 cases. The range of bone defects was 9.0 cm × 2.5 cm-17.0 cm × 2.5 cm. The preoperative spiral CT scan was performed and three-diamensional skull model was obtained. Titanium prosthetics of mandibular defects were designed and fabricated through multi-step procedure of reverse engineering and rapid prototyping. Titanium prosthetics were used for one-stage repair of mandibular bone defects, then two-stage implant denture was performed after 6 months. Results The individualized titanium prosthetics were inserted smoothly with one-stage operative time of 10-23 minutes. All the cases achieved incision healing by first intention and the oblique mandibular movement was corrected. They all got satisfactory face, had satisfactory contour and good occlusion. In two-stage operation, no loosening of the implants was observed and the abutments were in good position with corresponding teeth which were designed ideally before operation. All cases got satisfactory results after 1-9 years of follow-up. At last follow-up, X-ray examinations showed no loosening of implants with symmetry contour. Conclusion Computer assisted design and three-dimensional skull model techniques could accomplish the design and manufacture of individualized prosthetic for the repair of mandibular bone defects.
Objective To review recent advance in the research and appl ication of computer aided forming techniques for constructing bone tissue engineering scaffolds. Methods The l iterature concerning computer aided forming techniques for constructing bone tissue engineering scaffolds in recent years was reviewed extensively and summarized Results Several studies over last decade have focused on computer aided forming techniques for bone scaffold construction using various scaffold materials, which is based on computer aided design (CAD) and bone scaffold rapid prototyping (RP). CAD include medical CAD, STL, and reverse design. Reverse design can fully simulate normal bone tissue and could be very useful for the CAD. RP techniques include fused deposition model ing, three dimensional printing, selected laser sintering, three dimensional bioplotting, and low-temperature deposition manufacturing. These techniques provide a new way to construct bone tissue engineering scaffolds with complex internal structures. Conclusion With rapid development of molding and forming techniques, computer aided forming techniques are expected to provide ideal bone tissue engineering scaffolds.
Objective Calcium phosphate bioceramics has a broad appl ication prospect because of good biocompatibil ity, but porous scaffolds with complex shape can not be prepared by the traditional methods. To fabricate porous calcium phosphate ceramics by rapid prototyping and to investigate the in vitro osteogenic activities. Methods The porous calcium phosphate ceramics was fabricated by rapid prototyping. The bone marrow mesenchymal stem cells (BMSCs)were isolated from bone marrow of Beagle canine, and the 3rd passage BMSCs were seeded onto the porous ceramics. The cell/ceramics composite cultured in osteogenic medium were taken as the experimental group (group A) and the cell/ceramics composite cultured in growth medium were taken as the control group (group B). Meanwhile, the cells seeded on the culture plate were cultured in osteogenic medium or growth medium respectively as positive control (group C) or negative control (group D). After 1, 3, and 7 days of culture, the cell prol iferation and osteogenic differentiation on the porous ceramics were evaluated by DNA quantitative analysis, histochemical staining and alkal ine phosphatase (ALP) activity. After DiO fluorescent dye, the cell adhesion, growth, and prol iferation on the porous ceramics were also observed by confocal laser scanning microscope (CLSM). Results DNA quantitative analysis results showed that the number of BMSCs in all groups increased continuously with time. Plateau phase was not obvious in groups A and B, but it was clearly observed in groups C and D. The CLSM observation indicated that the activity of BMSCs was good and the cells spread extensively, showing good adhesion and prol iferation on the porous calcium phosphate ceramics prepared by rapid prototyping. ALP quantitative analysis results showed that the stain of cells on the ceramics became deeper and deeper with time in groups A and B, the staining degree in group A were ber than that in group B. There was no significant difference in the change of the ALP activity among 4 groups at the first 3 days (P gt; 0.05); the ALP activity increased obviously in 4 groups at 7 days, group A was significantly higher than other groups (P lt; 0.05) and groups C, D were significantly higher than group D (P lt; 0.05). Conclusion The porous calcium phosphate ceramics has good cytocompatibil ity and the designed pores are favorable for cell ingrowth. The porous ceramicsfabricated by rapid prototyping has prominent osteogenic differentiation activity and can be used as a choice of scaffolds for bone tissue engineering.
Objective To explore and evaluate the accuracy and feasibil ity of individual rapid prototype (RP) drill templates for atlantoaxial pedicle screw implantation. Methods Volumetric CT scanning was performed in 8 adult cadaveric atlas and axis to collect Dicom format datas. Then three-dimensional (3D) images of atlas and axis were reconstructed and the parameters of pedicles of 3D model were measured by using software Mimics 10.01. The 3D model was saved by STLformat in Mimics. The scattered point cloud data of 3D model were processed and the 3D coordinate system was located in software Imageware 12.1. The curves and surfaces of 3D model were processed in software Geomagic Studio 10. The optimal trajectory of pedicle screw was designed and a template was constructed which accorded with the anatomical morphology of posterior arch of atlas and lamina of axis by using software Pro/Engineer 4.0. The optimal trajectory of pedicle screw and the template were integrated into a drill template finally. The drill template and physical models of atlas and axis were manufactured by RP (3D print technology). The accuracy of pilot holes of drill templates was assessed by visually inspecting and CT scanning. Results The individual drill template was used conveniently and each template could closely fit the anatomical morphology of posterior arch of atlas and lamina of axis. Template loosening and shifting were not found in the process of screw implantation. Thirty-two pedicle screws were inserted. Imaging and visual inspection revealed that the majority of trajectories did not penetrate the pedicle cortex, only 1 cortical penetration was judged as noncritical and did not injury the adjacent spinal cord, nerve roots, and vertebral arteries. The accuracy of atlas pedicle screw was grade 0 in 15 screws and grade I in 1 screw, and the accuracy of axis pedicle screw was grade 0 in 16 screws. Conclusion The potential of individual drill templates to aid implantation of atlantoaxial pedicle screw is promising because of its high accuracy.
Objective To investigate the clinical typing and their relevant surgical treatment principle and method of pressure sore. Methods From January 1983 to April 2006, 122 patients with 179 pressure sores were treated. There were 93 males and29 females, aging 1568 years. The pressure sores were located at sacrococcygeus (54 lesions), petrochanteric region (37 lesions), ischial tuberosity (30 lesions), heel (17 lesions), olecranon (15 lesions), scapula (9 lesions), lateral malleolar (7 lesions), caput fibulace (4 lesions), pretibial (3 lesions), and lumbar region (3 lesims)respectivly. The disease course was from 2 months to 11 years. The areas of pressure sores were from 1.5 cm× 1.0 cm to 20.0 cm×18.0 cm. According to the wound characteristics, the pressure sores were divided into three types：sinus type（12/179）, ulcer type （74/179） and mixed type（93/179）.Aimed at different types of pressure sore, skin grafting, skin flap and myocutaneous flap were employed to repair wound. The areas of flaps were from 5.0 cm×3.5 cm to 26.0 cm×14.5 cm. The areas of skin grafting were from 7 cm×5 cm to 23 cm×12 cm. Results All wounds of sinus type healed by firstintention except one; and all flaps survived. All wounds of uler type healed byfirst intention; and the flaps survived completely except two which had a partial necrosis. All flaps which harvested to repair 93 pressure sores of mixed typewere survived. But one or two sinus occurred in 8 cases. Two healed by operation, and the others healed by dressing exchange. The wounds healed by first intention. The donor sites healed by first intention. The routine followup in 73 patients after 6 months showed that the recurrence appeared in 4 mixed type. The recurrence rate was 55% and the other patients had good outcome. Conclusion Clinical typing of pressure sore is helpful to select the suitable operation method and improve the rate of success.
Objective To introduce the recent advances of the application of computer technology in tissue engineering. Methods The recent original articlesrelated to computer technology, medical image technology, computer-aided design, the advanced manufacture technology were summarized and systematically analyzed.Results Computer-aided tissue engineering is a new fieldon tissue engineering. It is the future direction of tissue engineering study. This article reviews recent development of medical CT/MRI scanning, three-dimensional reconstruction, anatomical modeling, computeraided design, computer-aided manufacturing, rapid prototyping， RP manufacturing of tissue engineering scaffolds and computeraided implantation.Conclusion Computer-aided tissue engineering can be used in scaffolds design and fabrication, computer-aided artificial tissue implantation. It is a new field on tissue engineering.
Objective To build up a new contour and functional reconstruction technique of mandibular defects with rapid prototyping and reverse engineering technique. Methods From April 2002 to August 2004, 4 cases of mandibular defects due to resection of large mandible lesion were treated. Of 4 patients, there were 3 females and 1 male, with an age range of 21-42 years, which underwent secondary operation and presented a deviation as mandibular movement. The openingmouth extent was 1.8-2.5 cm(2.2 cm on average). The data of defects area were renewed withMimics and Geomagic Studio software; and the titanium reconstructive frame was designed and manufactured with rapid prototyping technigue. Defect were reconstructed by using CT digital data of patients. Results The CT data could be used by image software directly. The implant design could be completed by computer-aimed design(CAD)/computer-aided manufacture(CAM). The resin model and titanium frame were manufactured accurately by RP technique. Four patients achieved one stage healing. After a follow-up of 3 months to 2 years, largemandibular defect was reconstructed satisfactorily and the opening-mouth extent was 3.03.4 cm(3.2 cm on average). The occluding relation was normal. The implant denture was put on and the mastication function was good in 1 case. Conclusion Individual design and repair of large mandibular defect with CAD/CAM techniques is worth extending application clinically. It is a simple and accurate method.
Objective To investigate the methods of establishing 3-dimensional skull model using electron beam CT(EBCT) data rapid prototyping technique, andto discuss its application in repairing crainomaxillofacial trauma. Methods The data were obtained by EBCTcontinuous volumetric scanning with 1.0 mm slice at thickness. The data were transferred to workstation for 3-dimensional surface reconstruction by computeraided design software and the images were saved as STL file. The data can be usedto control a laser rapid-prototyping device(AFS-320QZ) to construct geometricmodel. The material for the model construction is a kind of laser-sensitive resinpower, which will become a mass when scanned by laser beam .The design and simulation of operation can be done on the model. The image data were transferred to the device slice by slice. Thus a geometric model is constructed according to the image data by repeating this process. Preoperative analysis, surgery simulation and implant of bone defect could be done on this computer-aided manufacture d3D model. One case of craniomaxillofacial bone defect resulting from trauma wasreconstructed with this method. The EBCT scanning showed that the defect area was 4 cm×6 cm. The nose was flat and deviated to left. Results The -3dimensional -skull was reconstructed with EBCT data and rapid prototyping technique. The model can display the structure of 3-dimenstional anatomyand their relationship.The prefabricated implant by 3-dimensional model was well-matched with defect .The deformities of flat and deviated nose were corrected. The clinical result wassatisfactory after a follow-up of 17 months. Conclusion The 3-dimensional model of skull can replicate the prototype of disease and play an important role in the diagnosis and simulation of operation for repairing craniomaxillofacial trauma.
Objective To design a new custom-made artificial semi-knee joint based on rapid prototyping(RP) technique and to explore a method to solve necroses of allocartilage in hemi-joint allotransplantation. Methods Based on the extracted 3D contour image of the articular cartilage of femoral condyle, the custom-made artificial semi-knee joint was designed with Surfacer 9.0 image processingsoftware. The artificial semi-knee joint design used the femoral condylar 3D contour of the patient as the outer face and the subchondral bone 3D contour of allograft bone as inner face. One dado for medullary nailand two for special designing cages which were used to fix the cartilage into the allograft were added on the inner face. After being converted into RP data format, the computerassisted design was imported into the LPS600 rapid prototyping machine, and the prototype was achieved. Furthermore, the prototype could be modified by hand according to the design. Then the RP model was used as a positive mould to build up a silica gel negativemould, and the negative mould was sent to the factory to manufacture Ti-6Al-4V alloy articular cartilage through ordinary mould-melted founding process. Finally, the whole metal cartilage was completed after melting two special cages on it andpolishing it. Results A new custom-made artificial semi-knee joint was made ad used to treat a 14-year old patient. The custom-made artificial semi-knee joint and the subchondral bone were a perfect match. The operative result was satisfactory. The patient could walk 5 weeks after operation. The bone healing of the auto-bone and allo-bone was achieved 6 months later. A follow-up period lasting 1 yearshowed that the knee joint played a good function. Conclusion The artificial semi-knee joint is a good match for the allograft boneand a good idea to solve necroses of allocartilage in hemijoint allotransplantation.
Objective To compare the differences of chromosome aberration and Rb 1 gene mutation among 3 cloned cells of SO-Rb50 cell line of retinoblastoma. Methods 1.Three cell cloned strains named MC2, MC3, MC4 were isolated from SO-Rb50. 2. Gbanding and karyotype analysis were performed on the llth passage cells of the 3 cell strains.3.All exons and the promoter region of the Rb gene were detected by PCR-SSCP analysis in tumor cell DNA extracted from the 3 cell strains. Results 1.Both numerical and structural chromosomal aberrations could be observed in these 3 cell strains.Several kinds of structural chromosomal aberrations were observed.The chromosome aberrations in the same passage of different cell strains were different.Aberration of chromosome 13 was rare and the aberration feature was different in the 3 cell strains.Five marker chromosomes were identified.M1,t(1;1)qter-p35∷q24-ter could befound in all cell strains.Two of them M4 and M5,have not been reported in SO-Rb50 cell line previously.2.SSCP analysis of exon 24 showed that MC411 and MC3138 had abnormal band. Conclusions The characteristics of heterogeneity of the original tumor cell line SO-Rb50are still kept during a long-term culture in vitro and the cloned strains had dynamic changes during this period.Aberration of chromosome 13 is not the only cause of RB;aberration of chromosome 1,a commom event in some neoplasias as well as in SO-Rb50, plays a meaningful role in the immortalization of this cell line. (Chin J Ocul Fundus Dis, 1999, 15: 146-148)