How does bone thickness affect the split pattern of sagittal ramus osteotomy?

This study examined the influence of bone thickness on the split pattern of sagittal ramus osteotomy at 62 sites using Dolphin 3D software. Four measurements of thickness were obtained from the preoperative computed tomography scans: measurement A was made 1.5 mm above the lingula, using the coronal and sagittal planes; measurement B was made at the same height as measurement A and 1 mm from the anterior border of the ramus; measurement C was obtained 5 mm distal to the last molar and 5 mm below the upper border of the mandible; measurement D was made in the area between the first and second molars, 6 mm above the mandibular border. Three-dimensional postoperative images were used to classify the split pattern into types, based on the classification of Plooij et al. The data were analyzed using the Kruskal–Wallis test, followed by Dunn post-hoc test. Thirty-five sagittal splits were type I, one was type II, 19 were type III, and seven were type IV. Type I presented the greatest thickness, whereas type IV presented the lowest. There was a statistically significant difference in thickness only for measurement A, when types I and IV were compared. The results indicate that thinner mandibular rami are more prone to bad splits.     

An Anatomic Study on Whether the Patella is Centered in an Ideal Anteroposterior Radiograph of the Knee

BackgroundCurrently, an anteroposterior radiograph of the knee is judged based on a centered position of the patella between the femoral condyles. We are not aware of any anatomic literature supporting this recommendation.Questions/PurposesOrthogonal images are required for accurate assessment of knee deformity. Although an image with the patella centered at the distal femur is generally accepted as a true anteroposterior (AP) radiograph of the knee, there is minimal anatomic data to support that this view is orthogonal to a true lateral view of the knee where the condyles are overlapped. We designed an anatomical study to test the relationship between these two radiographic views.MethodsWe studied 428 well-preserved cadaveric skeletons ranging from 40 to 79 years of age at death. Centering of the patella was calculated based on distal femoral and patellar widths. Multiple regression analysis was then performed to determine the relationship between patellar centering and age, gender, ethnicity, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), femoral anteversion, and contralateral centering.ResultsAverage patellar centering was 0.13 ± 0.04, indicating that the average patella was laterally positioned in the distal femur. Only mLDFA and contralateral centering showed statistically significant independent correlations with patellar centering with modest standardized beta coefficients of 0.10 and 0.23, respectively.ConclusionsIn the average specimen, the patella is laterally deviated by 13% of the condylar width. Clinicians should be aware that a lateral view with the femoral condyles overlapped is not always orthogonal to a patella-centered AP view when planning and implementing deformity correction.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-014-9419-3) contains supplementary material, which is available to authorized users.     

假肢适配重心对线技术的研究

目的提出一种基于人体重心变化的对线技术。方法利用重力传感器测取人体重力数据;根据平衡力学体系合力为0,由专用软件计算出人体重心的实时位置;通过串口通讯将重心的实时位置传输给控制单元,控制单元将实时位置的横坐标转换成电机的驱动脉冲信号,驱动与电机相连的装有激光器滑台进行重心跟随运动,从而可以根据重心的变化进行精确的对线。同时加入人体平衡功能检测,对假肢对线起辅助判断作用。结果和结论开发出通过检测人体重心位置的对线方法,可用于假肢矫形康复领域。     

Clinical Evaluation of Time Efficiency and Fit Accuracy of Lithium Disilicate Single Crowns between Conventional and Digital Impression

The purpose of this study was to demonstrate the time-efficiency and the clinical effectiveness of chairside-fabricated lithium disilicate single crowns by digital impressions compared to the conventional method. Thirteen patients requiring a single crown on the maxillary or mandibular premolar or first molar were assigned as study subjects. The impressions were obtained using the conventional method and two digital methods with intraoral scanners: AEGIS.PO (Digital Dentistry Solution, Seoul, Korea) and CEREC Omnicam (Sirona, Bensheim, Germany). Two types of lithium disilicate single crowns were obtained; a reference crown (by conventional workflow) and a chairside crown (by digital workflow). The total time taken for fabricating the chairside crown was recorded. The replica technique was performed to compare the marginal and internal fit of the two types of crowns. In addition, accuracy of the intraoral scanners was evaluated by the best-fit alignment method. The difference between the groups was analyzed using the two-tailed paired t-test or one-way ANOVA, followed by the Student–Newman–Keuls test for multiple comparisons. Statistical significance was accepted at p < 0.05 for all statistical tests. The time required to obtain the impressions by the AEGIS (7:16 ± 1:50 min:s) and CEREC (7:29 ± 2:03 min:s) intraoral scans was significantly lower than the conventional method (12:41 ± 1:16 min:s; p < 0.001). There was no significant difference between the intraoral scanners. The total working time to fabricate the chairside crown averaged 30:58 ± 4:40 min:s. The average marginal gap was not significantly different between the reference (107.86 ± 42.45 µm) and chairside (115.52 ± 38.22 µm) crowns (p > 0.05), based on results of replica measurement. The average internal gaps were not significantly different. The average value of the root mean square between the AEGIS (31.7 ± 12.3 µm) and CEREC (32.4 ± 9.7 µm) scans was not significantly different (p > 0.05). Intraoral scans required a significantly shorter impression time than the conventional method, and it was possible to fabricate a lithium disilicate crown in a single visit. There were no statistically significant differences in the fit of the restorations and accuracy of the intraoral scanners compared to the conventional workflow.     

Solvent‐Assisted Orientation of Poly(3‐hexylthiophene)‐Functionalized CdSe Nanorods Under an Electric Field

The synthesis of high‐aspect‐ratio (AR) CdSe (NRs) nanorods and their ordered assembly over large areas are reported. Long‐range ordering of hexagonal arrays of high‐AR NRs is achieved by a combination of controlled solvent evaporation and the use of an applied electric field. Vertically oriented assemblies of CdSe NRs functionalized with oligo‐ and polythiophene are also obtained. Aligned and oriented polythiophene CdSe NRs have potential applications in organic–inorganic hybrid bulk‐heterojunction photovoltaic devices.

     

双侧下颌升支矢状劈开截骨(BSSRO)后退术对下颌角区的影响

目的:研究BSSRO后退术后下颌角区形态的变化。方法:通过38例骨性下颌前突患者BSSRO后退手术前后头颅定位正侧位片及口腔X线计算机体层摄影(CBCT)片对硬组织结构定点测量。结果:2种测量均显示术后下颌角角度较术前减小,下颌升支坡度亦减小;下颌骨的宽度将增加。结论:BSSRO术后下颌角变小,下颌骨宽度增加;将使患者的面貌变宽,咬合功能有所改善。     

成人腰椎峡部裂性滑脱症与退变性滑脱症患者脊柱骨盆矢状面形态学研究

【摘要】 目的：研究成人腰椎峡部裂性滑脱症与退变性滑脱症患者的脊柱骨盆矢状面形态。方法：选择2009年3月~2012年3月就诊且有完整影像学资料的腰椎峡部裂性滑脱症与退变性滑脱症患者共58例,其中峡部裂性滑脱（峡部裂组）29例,男9例,女20例,年龄23~67岁,Ⅰ度滑脱22例、Ⅱ度7例,L4滑脱16例、L5滑脱13例;退变性滑脱（退变组）29例,男5例,女24例,年龄45~85岁,Ⅰ度滑脱22例、Ⅱ度7例,L3滑脱3例、L4滑脱23例、L5滑脱3例。峡部裂组和退变组患者ODI评分分别为25.5分和22.0分,两组间无统计学差异（P＞0.05）。测量两组脊柱骨盆矢状面形态学指标,包括骨盆入射角（pelvic incidence,PI）、骨盆倾斜角（pelvic tilt,PT）、骶骨倾斜角（sacral slope,SS）、腰椎前凸角（lumber lordosis,LL）、胸椎后凸角（thoracic kyphosis,TK）、矢状面轴向垂直距离（sagittal vertical axis,SVA）。同时测量两组病例的腰椎滑脱角、滑脱率以及滑脱距离。采用独立样本t检验对两组患者的上述指标进行比较。结果：峡部裂组患者LL、TK和滑脱角分别为52.2°±10.9°、25.3°±11.1°、9.9°±6.4°,明显高于退变组的44.2°±15.4°、23.4°±12.6°、6.0°±3.9°（P＜0.05）;退变组患者SVA为30.6±40.6mm,明显高于峡部裂组的4.6±24.9mm（P＜0.01）。两组患者的骨盆形态学参数PI（峡部裂组53.9°±11.5°,退变组55.8°±10.8°）、PT（17.0°±8.3°,22.9°±7.2°）、SS（36.9°±8.7°,33.4°±9.9°）以及腰椎滑脱率[（21.8±9.8）%,（19.7±7.8）%]、滑脱距离（6.2±2.7mm,5.6±1.9mm）均无统计学差异（P＞0.05）。结论：成人腰椎峡部裂性滑脱症与退变性滑脱症患者具有相似的骨盆形态,但峡部裂性滑脱症患者较退变性滑脱症患者表现为更大的胸椎后凸、腰椎前凸以及滑脱角。     

Long-Term Durability of the CLS Femoral Prosthesis in Patients with Osteonecrosis of the Femoral Head

Ninety-five hips with cementless wedge-shaped tapered CLS stem were evaluated with a mean duration of 12.7 years (range, 10.7–17.3 years). All patients were young and diagnosed with osteonecrosis of the femoral head. The Harris hip score was 92 at the latest follow-up. A subsidence greater than 3 mm was found in 3 hips (3.2%). Focal femoral osteolysis was found in 12 hips (12.6%). Endosteal bone formation and bony pedestal were observed in 94 hips (98.9%) and in 26 hips (27.4%), respectively. With revision for stem loosening as the end point, the survivorship showed 98.9% (95% CI, range 96.9%–100%) at 13 years. Stem alignment and proximal femur morphology did not influence loosening of the stem (p > 0.05).