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Tomohisa Nagasao - One of the best experts on this subject based on the ideXlab platform.
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3-D analysis of dislocation in Zygoma fractures.
Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery, 2013Co-Authors: Masahiro Toriumi, Tomohisa Nagasao, Tomoki Itamiya, Yusuke Shimizu, Hiroki Yasudo, Yoshiaki Sakamoto, Hisao Ogata, Kazuo KishiAbstract:Abstract Objective When fractured, Zygomas rotate and dislocate. The present study quantitatively elucidates the pattern of the rotation. Methods 50 patients with tri-pod-type Zygoma fractures were involved in this study. After defining a 3-dimensional coordinate system – consisting of the M–L axis (the axis directed from the medial to lateral side of the skull), I–S axis (directed from the inferior to superior side), and P–A axis (directed from the posterior to anterior side), the degree with which the fractured Zygomas rotated around each of these axes was measured using 3-dimensional graphic software. Thereafter, the tendency of the rotation was compared between the three rotational axes. Results Rotation around the I–S axis was the most frequent with a 96% incidence, followed by a substantial margin by rotation around the M–L axis with a 26% incidence; rotation around the P–A axis was rare, with an incidence of 10%. Furthermore, the degree of P–A axis rotation was minor compared to I–S and M–L axis rotations. Conclusion The main factor of Zygoma dislocation in Zygoma fracture is rotation around the I–S axis. This finding is helpful for effective performance to reposition fractured Zygomas.
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An anatomical study on the position of the summit of the Zygoma: theoretical bases for reduction malarplasty.
Plastic and reconstructive surgery, 2011Co-Authors: Tomohisa Nagasao, Yusuke Shimizu, Junpei Miyamoto, Yuji Nakanishi, Asako Hatano, Keizo Fukuta, Kazuo KishiAbstract:Background To achieve optimal outcomes in reduction malarplasty, the area of Zygoma from which volume should be reduced must be accurately identified. This anatomical study aims to evaluate the location of the Zygoma region that contributes most to the protrusion of the cheek. Methods The morphology of the Zygoma was studied on 121 Japanese adults (73 men and 48 women). The midpoint of the inferior orbital rim, Zygomaticomaxillary junction, the junction between the frontal process and the Zygomatic arch, and the lateral orbital rim were marked to be used as anatomical reference points. Then, a vertical plane intersecting the anterior and posterior edges of the Zygoma was marked. The point of the Zygoma most distant from the plane was defined as the summit of the Zygoma. Three-dimensional measurement using graphic software was performed, and the positional relationships between the summit and the four reference points were evaluated. Results In terms of horizontal position, the summit is located lateral to the lateral orbital rim and medial to the junction between the frontal process and the Zygomatic arch. Regarding vertical position, the summit exists at higher positions in men than in women. Conclusions The summit of the Zygoma is located medial to the junction of the frontal process and Zygomatic arch. Therefore, bone incision lines should be placed medial to the posterior edge of the frontal process in reduction malarplasty; effective correction of the protrusion cannot be achieved solely by detachment of the Zygomatic arch. The summit is located higher for men than for women. Therefore, bone incision lines should be placed higher for men than for women.
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Experimental evaluation of relapse-risks in operated Zygoma fractures.
Auris nasus larynx, 2008Co-Authors: Maki Nagasao, Tomohisa Nagasao, Yorihisa Imanishi, Toshiki Tomita, Tamotsu Tamaki, Kaoru OgawaAbstract:Abstract Objectives Prevention of relapse, or postoperative dislocation, of the fixed Zygoma is necessary to achieve optimal results in the treatment of Zygoma fractures. Assuming that the occurrence of intensified stresses on mastication at the screw–bone interface (SBI) constitutes the essential cause of the relapse, we evaluated the stresses for three different fixation methods—fixation at the frontal process (FP), inferior orbital rim (IOR), and Zygomatico-maxillary buttress (ZMB). Methods We used 10 computer-aided design (CAD) models simulating Zygoma fractures in the experiment. For each CAD model, we fixed the fractured Zygoma with four screws and one mini-plate at the FP, IOR, or ZMB. After applying a 5.5 kg force simulating mastication, we calculated the intensity and distribution patterns of the stresses occurring at the SBIs of the fixation screws using the finite element method. Thereby, we evaluated dynamic stability of the fixed Zygoma for each of the three fixation methods. Results Greater stresses occur at the SBIs with IOR fixation than at those with FP and ZMB fixation. Although the stresses occurring at the SBIs on mastication demonstrated evenly distributed patterns with the FP and ZMB fixation, the stresses demonstrated concentration on one screw with the IOR fixation. Conclusions The fixed Zygoma is more likely to cause relapse with the IOR fixation than with the FP or ZMB fixation. Hence, in performing Zygoma fixation at the IOR, care should be taken to minimize the likelihood of postoperative relapse that is caused by skewed distribution of the stresses on the fixation screws.
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Effectiveness of additional transmalar kirschner wire fixation for a Zygoma fracture
Plastic and reconstructive surgery, 2007Co-Authors: Tomohisa Nagasao, Hisao Ogata, Ikkei Tamada, Junpei Miyamoto, Tsuyoshi Kaneko, Maki Nagasao, Tatsuo NakajimaAbstract:Background: The purpose of this study was to verify the effectiveness of transmalar Kirschner wire fixation as additional fixation for the treatment of Zygoma fractures. Methods: The authors compared two methods for Zygoma fixation at the frontoZygomatic suture from both theoretical and clinical viewpoints: miniplate fixation (plate fixation) and miniplate fixation with an additional transmalar Kirschner wire fixation (wire plus plate fixation). For the theoretical study, the authors produced Zygoma fractures on 20 skull simulation models; these were generated on the basis of computed tomographic data of actual dry skulls. In their simulation surgery, they fixed the fractured Zygoma with the above-mentioned two fixation methods, producing 20 plate fixation models and 20 wire plus plate fixation models. A 10-kgf load was then applied on the fractured Zygoma in the anteroposterior and superoinferior directions. Finally, the stresses around the fixation screws and the deviation of the Zygoma were calculated using finite element analysis. For the clinical study, the authors compared the postoperative Zygoma alignment based on computed tomography of six patients treated with plate fixation and eight patients treated with wire plus plate fixation using a visual analogue scale. Results: In the theoretical study, the wire plus plate fixation models demonstrated a significant decrease in both the stresses around the screws and the deviation of the fractured bone compared with the plate fixation models. In the clinical study, the visual analogue scale scores for the wire plus plate fixation group were significantly higher than those for the plate fixation group. Conclusion: Because the additional transmalar Kirschner wire fixation can effectively increase the stability of the fractured Zygoma that has been fixed with one miniplate, it should be recommended as an effective technique for the treatment of complicated Zygoma fractures.
Marcin Czerwinski - One of the best experts on this subject based on the ideXlab platform.
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C-Arm Assisted Zygoma Fracture Repair: A Critical Analysis of the First 20 Cases
Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons, 2014Co-Authors: Marcin CzerwinskiAbstract:Purpose Currently used open reduction and internal fixation techniques of Zygoma fracture repair are not optimal. Surgical exposure of those sites needed to allow for accurate reduction and for rigid fixation has a high possibility of negative consequences. The objective of the present study was to present a single-incision, single-fixation site Zygoma fracture repair technique using a single Zygoma c-arm view to quantitatively determine its accuracy, complication rate, and practical aspects in a clinical series. Materials and Methods In a prospective study, consecutive patients with isolated, unilateral, displaced Zygoma fractures not requiring orbital floor exploration treated using a c-arm–assisted repair technique at the author's institution from 2009 to 2011 were included. Objective outcomes assessed included accuracy of Zygoma realignment (on postoperative computed tomogram), ocular globe projection symmetry (using a Naugle exophthalmometer), complication rate, and operative duration. Statistical analysis was performed using the Student t test. Results Twenty patients were included. Differences in Zygoma projection, width, and height between the uninjured and repaired sides of the face were clinically noteworthy (>3 mm) in the first patient only. Average differences of these parameters for all 20 patients were clinically and statistically insignificant. Differences in ocular globe projection between the uninjured and repaired sides of the face for each patient were no greater than 2 mm. The average difference in globe projection for all 20 patients was also clinically and statistically insignificant. No major complications occurred, and the average operative duration was 76 minutes. Conclusions The present study shows that the c-arm–assisted Zygoma fracture repair technique is accurate, has a low complication rate, can be performed quickly, and has a relatively low level of difficulty.
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Rapid intraoperative Zygoma fracture imaging.
Plastic and reconstructive surgery, 2009Co-Authors: Marcin Czerwinski, Wendy L. Parker, Lorne Beckman, H. Bruce WilliamsAbstract:Background: A fractured Zygoma frequently results in an aesthetically displeasing facial asymmetry. Open reduction and internal fixation may accurately realign the facial skeleton but often with undesirable sequelae. The authors' objective was to develop a precise technique of intraoperative Zygoma fracture imaging using a C-arm to permit anatomical fracture realignment while reducing the extent of skeletal exposure required. The simplicity and accessibility of this method should allow its widespread clinical application. Methods: First, using a model skull, the relative positions of the C-arm required to adequately depict Zygoma projection, width, arch contour, and Zygoma rotation were defined. Second, diverse Zygoma fracture types were created in six cadaver heads with a Mini Bionix machine and were repaired using C-arm guidance; accuracy was confirmed with postoperative computed tomography. Third, after defining optimal operating room setup, the accuracy in a clinical case was assessed. Results: Two C-arm views were defined. The Zygoma projection view (C-arm at 70 to 90 degrees to the skull's coronal plane) allows visualization of projection, width, and contour. The rotation view (C-arm at 70 to 90 degrees to the skull's sagittal plane) allows visualization of Zygoma rotation. Postoperative computed tomographic imaging confirmed anatomical repair in all cases. Average operating room duration was less than 30 minutes, with operating room times decreasing progressively. Conclusions: The authors have developed an accurate technique of intraoperative Zygoma fracture imaging and reduction guidance. This technique may decrease the risks of open access by potentially limiting direct skeletal exposure to buttresses where skeletal stabilization is required. In addition, this method is simple, can be learned and used rapidly, and is readily accessible.
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Quantitative analysis of the orbital floor defect after Zygoma fracture repair.
Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons, 2008Co-Authors: Marcin Czerwinski, Ali Izadpanah, Jeffrey Chankowsky, H. Bruce WilliamsAbstract:Purpose Moderate-energy Zygoma fractures result frequently in a posteromedially displaced bone fragment. Closed reduction using a force vector directed in an anterolateral direction frequently produces stable repair of these injuries. Exploration of the orbital floor (OF) is not routinely undertaken. However, as the Zygoma forms a significant portion of the OF, realignment may create an unrecognized OF defect. Routine OF exploration may be unnecessary and carries the risks of eyelid malposition, scarring, and extraocular muscle injury. Our goal was to quantitatively describe the effect of Zygoma reduction on OF defect size and identify predictors for floor exploration. Patients and Methods Retrospectively, patients with moderate energy Zygoma fractures were identified. Fractures inadequately reduced on the postoperative computed tomography (CT) scan or those which underwent OF exploration were excluded. The sizes of preoperative and postoperative floor defects from CT scans were measured. Globe projection was measured. Statistical analysis was carried out using Student's t test. Results Of 102 identified patients, 15 satisfied the inclusion criteria. The average pre- and postoperative OF defects measured 0.3 and 0.6 cm 2 , respectively. This difference approached statistical significance, but was clinically insignificant except in 1 patient. Similarly, globe projection was clinically similar between the repaired and unaffected sides, except in the same patient. Conclusion In majority, repair of moderate energy Zygoma fractures does not clinically significantly increase OF defect or produce enophthalmos. In patients with significant displacement of the Zygoma at the level of OF with comminution of floor fragments, the reduction maneuver may create a critical size defect and we believe should be followed by floor exploration.
H. Bruce Williams - One of the best experts on this subject based on the ideXlab platform.
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Rapid intraoperative Zygoma fracture imaging.
Plastic and reconstructive surgery, 2009Co-Authors: Marcin Czerwinski, Wendy L. Parker, Lorne Beckman, H. Bruce WilliamsAbstract:Background: A fractured Zygoma frequently results in an aesthetically displeasing facial asymmetry. Open reduction and internal fixation may accurately realign the facial skeleton but often with undesirable sequelae. The authors' objective was to develop a precise technique of intraoperative Zygoma fracture imaging using a C-arm to permit anatomical fracture realignment while reducing the extent of skeletal exposure required. The simplicity and accessibility of this method should allow its widespread clinical application. Methods: First, using a model skull, the relative positions of the C-arm required to adequately depict Zygoma projection, width, arch contour, and Zygoma rotation were defined. Second, diverse Zygoma fracture types were created in six cadaver heads with a Mini Bionix machine and were repaired using C-arm guidance; accuracy was confirmed with postoperative computed tomography. Third, after defining optimal operating room setup, the accuracy in a clinical case was assessed. Results: Two C-arm views were defined. The Zygoma projection view (C-arm at 70 to 90 degrees to the skull's coronal plane) allows visualization of projection, width, and contour. The rotation view (C-arm at 70 to 90 degrees to the skull's sagittal plane) allows visualization of Zygoma rotation. Postoperative computed tomographic imaging confirmed anatomical repair in all cases. Average operating room duration was less than 30 minutes, with operating room times decreasing progressively. Conclusions: The authors have developed an accurate technique of intraoperative Zygoma fracture imaging and reduction guidance. This technique may decrease the risks of open access by potentially limiting direct skeletal exposure to buttresses where skeletal stabilization is required. In addition, this method is simple, can be learned and used rapidly, and is readily accessible.
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Quantitative analysis of the orbital floor defect after Zygoma fracture repair.
Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons, 2008Co-Authors: Marcin Czerwinski, Ali Izadpanah, Jeffrey Chankowsky, H. Bruce WilliamsAbstract:Purpose Moderate-energy Zygoma fractures result frequently in a posteromedially displaced bone fragment. Closed reduction using a force vector directed in an anterolateral direction frequently produces stable repair of these injuries. Exploration of the orbital floor (OF) is not routinely undertaken. However, as the Zygoma forms a significant portion of the OF, realignment may create an unrecognized OF defect. Routine OF exploration may be unnecessary and carries the risks of eyelid malposition, scarring, and extraocular muscle injury. Our goal was to quantitatively describe the effect of Zygoma reduction on OF defect size and identify predictors for floor exploration. Patients and Methods Retrospectively, patients with moderate energy Zygoma fractures were identified. Fractures inadequately reduced on the postoperative computed tomography (CT) scan or those which underwent OF exploration were excluded. The sizes of preoperative and postoperative floor defects from CT scans were measured. Globe projection was measured. Statistical analysis was carried out using Student's t test. Results Of 102 identified patients, 15 satisfied the inclusion criteria. The average pre- and postoperative OF defects measured 0.3 and 0.6 cm 2 , respectively. This difference approached statistical significance, but was clinically insignificant except in 1 patient. Similarly, globe projection was clinically similar between the repaired and unaffected sides, except in the same patient. Conclusion In majority, repair of moderate energy Zygoma fractures does not clinically significantly increase OF defect or produce enophthalmos. In patients with significant displacement of the Zygoma at the level of OF with comminution of floor fragments, the reduction maneuver may create a critical size defect and we believe should be followed by floor exploration.
Kazuo Kishi - One of the best experts on this subject based on the ideXlab platform.
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3-D analysis of dislocation in Zygoma fractures.
Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery, 2013Co-Authors: Masahiro Toriumi, Tomohisa Nagasao, Tomoki Itamiya, Yusuke Shimizu, Hiroki Yasudo, Yoshiaki Sakamoto, Hisao Ogata, Kazuo KishiAbstract:Abstract Objective When fractured, Zygomas rotate and dislocate. The present study quantitatively elucidates the pattern of the rotation. Methods 50 patients with tri-pod-type Zygoma fractures were involved in this study. After defining a 3-dimensional coordinate system – consisting of the M–L axis (the axis directed from the medial to lateral side of the skull), I–S axis (directed from the inferior to superior side), and P–A axis (directed from the posterior to anterior side), the degree with which the fractured Zygomas rotated around each of these axes was measured using 3-dimensional graphic software. Thereafter, the tendency of the rotation was compared between the three rotational axes. Results Rotation around the I–S axis was the most frequent with a 96% incidence, followed by a substantial margin by rotation around the M–L axis with a 26% incidence; rotation around the P–A axis was rare, with an incidence of 10%. Furthermore, the degree of P–A axis rotation was minor compared to I–S and M–L axis rotations. Conclusion The main factor of Zygoma dislocation in Zygoma fracture is rotation around the I–S axis. This finding is helpful for effective performance to reposition fractured Zygomas.
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An anatomical study on the position of the summit of the Zygoma: theoretical bases for reduction malarplasty.
Plastic and reconstructive surgery, 2011Co-Authors: Tomohisa Nagasao, Yusuke Shimizu, Junpei Miyamoto, Yuji Nakanishi, Asako Hatano, Keizo Fukuta, Kazuo KishiAbstract:Background To achieve optimal outcomes in reduction malarplasty, the area of Zygoma from which volume should be reduced must be accurately identified. This anatomical study aims to evaluate the location of the Zygoma region that contributes most to the protrusion of the cheek. Methods The morphology of the Zygoma was studied on 121 Japanese adults (73 men and 48 women). The midpoint of the inferior orbital rim, Zygomaticomaxillary junction, the junction between the frontal process and the Zygomatic arch, and the lateral orbital rim were marked to be used as anatomical reference points. Then, a vertical plane intersecting the anterior and posterior edges of the Zygoma was marked. The point of the Zygoma most distant from the plane was defined as the summit of the Zygoma. Three-dimensional measurement using graphic software was performed, and the positional relationships between the summit and the four reference points were evaluated. Results In terms of horizontal position, the summit is located lateral to the lateral orbital rim and medial to the junction between the frontal process and the Zygomatic arch. Regarding vertical position, the summit exists at higher positions in men than in women. Conclusions The summit of the Zygoma is located medial to the junction of the frontal process and Zygomatic arch. Therefore, bone incision lines should be placed medial to the posterior edge of the frontal process in reduction malarplasty; effective correction of the protrusion cannot be achieved solely by detachment of the Zygomatic arch. The summit is located higher for men than for women. Therefore, bone incision lines should be placed higher for men than for women.
Junpei Miyamoto - One of the best experts on this subject based on the ideXlab platform.
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An anatomical study on the position of the summit of the Zygoma: theoretical bases for reduction malarplasty.
Plastic and reconstructive surgery, 2011Co-Authors: Tomohisa Nagasao, Yusuke Shimizu, Junpei Miyamoto, Yuji Nakanishi, Asako Hatano, Keizo Fukuta, Kazuo KishiAbstract:Background To achieve optimal outcomes in reduction malarplasty, the area of Zygoma from which volume should be reduced must be accurately identified. This anatomical study aims to evaluate the location of the Zygoma region that contributes most to the protrusion of the cheek. Methods The morphology of the Zygoma was studied on 121 Japanese adults (73 men and 48 women). The midpoint of the inferior orbital rim, Zygomaticomaxillary junction, the junction between the frontal process and the Zygomatic arch, and the lateral orbital rim were marked to be used as anatomical reference points. Then, a vertical plane intersecting the anterior and posterior edges of the Zygoma was marked. The point of the Zygoma most distant from the plane was defined as the summit of the Zygoma. Three-dimensional measurement using graphic software was performed, and the positional relationships between the summit and the four reference points were evaluated. Results In terms of horizontal position, the summit is located lateral to the lateral orbital rim and medial to the junction between the frontal process and the Zygomatic arch. Regarding vertical position, the summit exists at higher positions in men than in women. Conclusions The summit of the Zygoma is located medial to the junction of the frontal process and Zygomatic arch. Therefore, bone incision lines should be placed medial to the posterior edge of the frontal process in reduction malarplasty; effective correction of the protrusion cannot be achieved solely by detachment of the Zygomatic arch. The summit is located higher for men than for women. Therefore, bone incision lines should be placed higher for men than for women.
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Effectiveness of additional transmalar kirschner wire fixation for a Zygoma fracture
Plastic and reconstructive surgery, 2007Co-Authors: Tomohisa Nagasao, Hisao Ogata, Ikkei Tamada, Junpei Miyamoto, Tsuyoshi Kaneko, Maki Nagasao, Tatsuo NakajimaAbstract:Background: The purpose of this study was to verify the effectiveness of transmalar Kirschner wire fixation as additional fixation for the treatment of Zygoma fractures. Methods: The authors compared two methods for Zygoma fixation at the frontoZygomatic suture from both theoretical and clinical viewpoints: miniplate fixation (plate fixation) and miniplate fixation with an additional transmalar Kirschner wire fixation (wire plus plate fixation). For the theoretical study, the authors produced Zygoma fractures on 20 skull simulation models; these were generated on the basis of computed tomographic data of actual dry skulls. In their simulation surgery, they fixed the fractured Zygoma with the above-mentioned two fixation methods, producing 20 plate fixation models and 20 wire plus plate fixation models. A 10-kgf load was then applied on the fractured Zygoma in the anteroposterior and superoinferior directions. Finally, the stresses around the fixation screws and the deviation of the Zygoma were calculated using finite element analysis. For the clinical study, the authors compared the postoperative Zygoma alignment based on computed tomography of six patients treated with plate fixation and eight patients treated with wire plus plate fixation using a visual analogue scale. Results: In the theoretical study, the wire plus plate fixation models demonstrated a significant decrease in both the stresses around the screws and the deviation of the fractured bone compared with the plate fixation models. In the clinical study, the visual analogue scale scores for the wire plus plate fixation group were significantly higher than those for the plate fixation group. Conclusion: Because the additional transmalar Kirschner wire fixation can effectively increase the stability of the fractured Zygoma that has been fixed with one miniplate, it should be recommended as an effective technique for the treatment of complicated Zygoma fractures.
