How Partial Skull Defect Affects Vulnerability of the Skull in Traumatic Situations: A Biomechanical Study.

Background: Part of the skull can be lost due to neurosurgical diseases or trauma. Skulls with partial defects can develop different fracture patterns from those of intact skulls. This study aims to clarify the differences. Methods: A 3-dimensional skull model was produced by referring to the computer-tomography data of a 23-year-old intact male volunteer. We defined the model as Intact Model. Another model was produced by removing part of the frontal bone, which was defined as Defect Model. Dynamic simulations of impacts were performed varying the site and direction of impact. Fracture patterns caused by the impacts were calculated using dynamic analysis software (LS-DYNA; Livermore Software Technology Corp.) and were compared between the intact model and defect model. Results: When Defect Model was impacted, fracture involved wider areas than when Intact Model was impacted. This finding was observed not only when Defect Model was impacted on its defect side but also when it was impacted on its intact side. Conclusions: When a skull carrying a defect on one side is impacted, serious fracture occurs even when the non-defect side is impacted, meaning that a skull with a defect is vulnerable to impacts on the non-defect side. This finding should be taken into consideration in deciding indications of skull defect reconstruction.

Hardness of Artificial Bone and Vulnerability of Reconstructed Skull-A Biomechanical Study.

Background: Various materials are used to reconstruct cranial defects. The present study focuses on what happens when reconstructed skulls are impacted in trauma situations. Using biomechanical analysis, the present study elucidates how the hardness of reconstruction material affects the vulnerability of reconstructed skulls. Methods: A 3-dimensional finite element model was produced simulating the skull of an intact adult male. A defect was made on the left hemi-frontal part of the skull model. The defect was restored with artificial bone with 3 different hardness models. These models were respectively defined as Hard Model (simulating reconstruction with titanium), Moderate Model (simulating reconstruction with a material equivalent to human bone), and Soft Model (simulating reconstruction with hydroxyl apatite). Virtual impacts were applied on these models in 9 patterns, and the conditions of subsequent fracture were evaluated using finite element analysis. For each of the 9 impact patterns, the conditions of subsequent fracture were compared among the 3 models. Results: In 8 of the 9 impact patterns, the condition of fracture was more widespread for Hard Model than for Moderate Model and Soft Model. Conclusions: Skulls reconstructed with a hard material can develop serious fracture if they are impacted again. Therefore, usage of hard materials should be avoided to prevent serious injuries from secondary trauma.

Efficacy of seasonal allergic rhinitis using an 810 nm diode laser system.

BACKGROUND AND AIMS: Allergic rhinitis annually reach epidemic proportions in Japan. Approximately 30 to 40% of the population suffers from allergic rhinitis during the spring season. Symptoms comprise rhinorrhea, nasal congestion, and sneezing accompanied by irritation and itching of the eyes. The Ohshiro Clinic started using the conventional Nd:YAG laser for the treatment of allergic rhinitis in 1993, and from 2005 we started using a diode laser-pumped Nd:YAG laser. From 2010, we adopted a novel 810 nm diode laser, and the present retrospective study examined the efficacy rate of the treatment of allergic rhinitis in the 2018 season with this system, compared with a previous study in 2011. We aimed to confirm the degree of improvement for each symptom to evaluate effectiveness of the diode laser treatment. SUBJECTS AND METHODS: Between January 8, 2018 and April 30, 2018, a large number of patients consulted our clinic with the major complaint of seasonal allergic rhinitis. They underwent a blood test, and the antigen-specific serum IgE antibody titers were measured for a definitive diagnosis of cedar pollinosis. A total of 211 target patients were treated during the trial period. The average age of the target group was 36.3 years, 134 males, and 77 females. The target patients were treated with lower nasal turbinate mucosal irradiation using a diode laser (ADL-20, Asuka Medical) delivering 810 nm at 7.5 W, with a total energy per treatment of 240 J/cm2. We adopted a five-step evaluation in accordance with the Japanese Guidelines for Allergic Rhinitis 2014 for the symptoms of rhinorrhea, sneezing and nasal obstruction. We assessed the degree of improvement in the severity of these symptoms following diode laser treatment from baseline to one month after treatment, in addition to assessing patient satisfaction with the degree of improvement in their quality of life (QOL). RESULTS: The 211 patients positive for cedar pollinosis by the antigen-specific serum IgE antibody tests were broken down by month by number and by improvement, no change or exacerbation as follows. January, 18 patients: 33.4%, 44.4% and 22.2%, respectively. February, 29: 10.4%, 44.4% and 22.2%, respectively. March, 146: 60.3%, 31.5% and 8.2%, respectively. April, 18: 77.8%, 16.7% and 5.5%, respectively. The monthly respective improvement, no change or worse patient QOL as percentages were as follows: January: 16.7%, 44.4% and 38.9%. February: 17.3%, 13.8% and 68.9%. March: 61.6%, 29.5% and 8.9%. April: 94.4%, 0.0% and 5.6%. The values for prevention of exacerbation versus exacerbation for each month were: January, 77.8% vs 22.2%; February, 41.4% vs 58.6%; March, 91.8% vs 8.2%; and April, 94.4% vs 5.6%. The mean efficacy rate for the trial period in the present study was therefore 52.6% which compared very favorably with the mean efficacy rate in the 2011 study of 53.4%. CONCLUSIONS: The results showed that the 810 nm diode laser offered a safe and effective solution for the uncomfortable symptoms of allergic rhinitis and could be well applied during the season of Japanese cedar pollen dispersion. Furthermore, a tendency towards high efficacy was demonstrated for laser treatment in class 6 cedar pollinosis patients, based on the specific IgE antibody test.

A biomechanical study of relationship between sternum defect patterns and thoracic respiration.

BACKGROUND: Various types of sternum defects are produced after the removal of thoracic tumors involving the sternum. The present study aims to elucidate the relationship between the defect patterns and their effects on thoracic respiration. METHODS: Ten sets of finite element models were produced simulating thoraces of 10 persons and termed normal models. With each of the 10 normal models, the sternum was removed in six different ways to produce new models termed defect models. Defect models were categorized into hemi-superior (H-S), hemi-inferior (H-I), hemi-whole length (H-W), bilateral-superior (B-S), bilateral-inferior (B-I), and bilateral-whole length (B-W) defect types, depending on the locations of the defects. Respiratory movement was dynamically simulated with these models. The volume change the thoraces present during respiration was measured to evaluate the effectiveness of thoracic respiration. This value - defined as ΔV - was calculated and was compared between normal and defect models. RESULTS: With H-W and B-W type models, ΔV dropped to around 20% of normal values. With H-S and B-S type models, ΔV dropped to around 50% of normal values. With H-I and B-I type models, ΔV presented values almost equivalent to those of normal models. CONCLUSION: Effectiveness of thoracic respiration is seriously impaired when the whole length of the sternum is absent. Reconstruction of the defect is essential for these cases. However, since the upper part of the sternum is most important for effective thoracic respiration, priority should be placed on the upper part in performing reconstruction.

Relationship between locations of rib defects and loss of respiratory function - a biomechanical study.

OBJECTIVE: The present study elucidates the relationship between the locations of rib defects and loss of respiratory function. METHODS: Ten sets of three-dimensional finite element models were produced from computed tomography data of 10 persons and categorized as normal type models. These models were modified by removing part of the ribs, and the resultant models were categorized as defect type models. Varying the location of the defects, six types of defect model were produced from each of the 10 normal models; the defects were made on the anterior-superior, anterior-inferior, lateral-superior, lateral-inferior, posterior-superior, and posterior-inferior regions of the thorax. To simulate respiration, contracture forces were applied to nonlinear springs modeling respiratory muscles for each of the normal and defect models. Difference in volume of the thoracic cavity between inspiration and expiration phases was viewed as the indicator of respiratory function and was defined as ΔV. The values of ΔV were compared between normal type models and their corresponding defect type models. RESULTS: Among the six types of defect, the degree of functional loss was greatest with those defects on the lateral-inferior part of the thorax, where ΔV of the affected side hemithorax drops to 38 to 45% of normal values, whereas ΔV was 62 to 88% with other defect models. CONCLUSION: Thoraces that have defects on their lateral-inferior regions present lower respiratory functioning than thoraces with other defect locations. Hence, in treating clinical cases where defects are expected to occur in this region, effort should be made to minimize the area of the defect.

A biomechanical study regarding the effect of tissue harvesting from the thorax on its movement during inspiration.

OBJECTIVE: In the practice of plastic surgery, ribs and cartilage are often harvested for use in auto-grafts. This study aimed to elucidate the effect of such harvesting on the inspiration movement of the thorax. MATERIALS AND METHODS: Sixteen three-dimensional computer simulation models were produced by reference to the CT data of 16 patients. To simulate the harvesting of ribs and costal cartilages, parts were removed from these thorax models, thereby producing models with different types of defect. By performing finite element calculation after applying contracture forces on the external intercostal muscles and diaphragm, the movement patterns exhibited by the thoraces during inspiration were analyzed. The relationships between the defect types and the movement patterns were evaluated with reference to the dynamic behavior of the sternum and the increase in thoracic volume. RESULTS: Although the removal of costal cartilage can cause asymmetric movement of the thorax, it did not affect the inspiration movement of the thorax. However, removal of two or more ribs not only caused asymmetric movement of the thorax, but also negatively affected that movement. Removal of two or three ribs impaired the expansion of the hemi-thorax on inspiration by 10% and 40%, respectively. CONCLUSION: The present study is the first to clarify the quantitative effect of tissue harvesting from the thorax on inspiration. The findings will be useful for surgeons when planning operations requiring harvesting of tissue from the thorax.

Extension of the jejunum in the reconstruction of cervical oesophagus with free jejunum transfer using the thoracoacrominal vessels as recipients.

BACKGROUNDS: The degree to which the jejunum can reach upward is a significant consideration in cervical oesophagus reconstruction with vascularised free jejunum transfer using the thoracoacrominal vessels as recipient vessels. The present study aims to elucidate this issue. MATERIALS AND METHODS: In 30 fresh cadavers, the thoracoacrominal vessels were dissected, and the jejunums were harvested, carrying the second branches of the superior mesenteric arteries and veins as their pedicles. After the mesenteric vessels were anastomosed to the thoracoacrominal vessels, the jejunums were advanced to their maximum upward degree, and the positions of the oral ends were evaluated referring to the hyoid bone. The evaluation was performed under three conditions. In the first condition, the jejunums were simply advanced. In the second condition, tension of the mesenteriums was reduced by incising their serosa. In the third condition, mesenterial incision was also performed, and the anastomosed pedicles were placed under the clavicles. RESULTS: The jejunums can reach superior to the hyoid bone by 2.1 ± 1.5 SD cm for males and by 1.9 ± 1.5 SD for females. By incising the mesenteric serosa, these distances can be extended by about 2 cm for males and 1 cm for females. Further extension of 2 cm can be obtained for both sexes by placing the pedicle under the clavicle. CONCLUSION: With patients whose neck regions lack vessels available for vascular anastomosis, the thoracoacrominal vessels are used in free jejunum transfer for cervical oesophagus reconstruction. The findings of the present study are useful in planning this type of reconstruction.

A case of congenital unilateral amastia.

Numerous reports have been published regarding the reconstruction of the breast, but the majority of these reports focus on breast reconstruction for defects caused by the removal of breast cancers. The authors treated a rare case of unilateral amastia where a 54-year-old female had a complete absence of the breast on one side, though the breast on the other side was intact. The defect was reconstructed successfully with a transverse rectus abdominis myocutaneous flap (TRAM) flap. The present study introduces this rare case with reference to past reports of amastia.

An anatomical study on the position of the summit of the zygoma: theoretical bases for reduction malarplasty.

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.