Calculation of joint moments following foot contact across two force plates

This study aimed to quantify the effect of combining the measurements from force plates when a subject's foot comes in contact with more than one force plate. A 3-Dimensional Gait Analysis (3DGA) was performed on a subject walking barefoot. Ten gait trials (good both) were captured where both subject's feet hit a single force plate. Then 20 gait trials (two force plates) were captured where either the right or left subject's foot was in contact with two force plates at a time. Kinematics were computed with VICON^® Plugin Gait and kinetics with a BodyLanguage^® (VICON, Oxford, UK) model that allowed the combination of force plate measurements. The kinetics traces from both sets of data were compared using variance component analysis. Results suggest that effects of how the moments were calculated were at most a third of those arising from stride to stride variability. This suggests that development of automated systems for determining foot contact coupled with arrays of more and smaller force plates than are commonly used might be useful to ensure the capture of good quality kinetic data in a wide range of patients.     

基于两种靶-滤过的数字乳腺机对致密型厚乳腺摄影结果的对比研究

目的 探讨对模拟致密型厚乳腺（压迫厚度>65 mm）的模体行全景数字乳腺X射线摄影（FFDM）检查,钼-铑（Mo-Rh）和钨-铑（W-Rh）两种靶-滤过组合对其辐射剂量及图像质量的影响。方法 用聚甲基丙烯酸甲酯有机玻璃（PMMA）模拟标准乳腺,再将铝片置于PMMA板中模拟致密型乳腺,对两组不同致密型（分别放置0.1和0.2 mm铝片）厚度为68 mm的模体进行自动、半自动曝光以及手动曝光,记录靶-滤过（T-F）组合方式、管电压、管电流、平均腺体剂量（AGD）、表面入射剂量（ESE）和图像质量因子反数值（IQFInv）。采用Pearson相关及回归分析评价AGD对IQFInv的影响,两组模体的靶-滤过组合对IQFInv和AGD的差异采用配对样本t检验。结果 AGD和IQFInv具有正相关（r=0.806~0.953,P<0.05）。对于0.1 mm铝片的模体,固定100 mAs或固定28 kVp,两组靶-滤过组合的AGD差异和IQFInv差异均具有统计学意义（t=3.162~8.028,P<0.05）。对于0.2 mm铝片的模体,固定100 mAs时,AGD差异和IQFInv差异均具有统计学意义（t=8.028、4.768,P<0.05）;固定28 kVp时,AGD差异具有统计学意义（t=7.730,P<0.05）,IQFInv差异没有统计学意义（P>0.05）。此外,固定100 mAs时,采用W-Rh,两组模体的IQFInv差异具有统计学意义（t=2.345,P<0.05）。结论 对致密型厚乳腺模体采用W-Rh组合较Mo-Rh组合能在保证影像质量的前提下降低辐射剂量。相同管电流时,W-Rh组合在高管电压下对致密程度较高的乳腺模体的影像显示更佳。     

Conventional screen/film vs reduced exposure photostimulable phosphor plate imaging in lower extremity venography: an ROC analysis

Half-exposure phosphor plates used in venography substantially reduce the total X-ray exposure to a patient while increasing the chance that all images will be of excellent diagnostic quality. Simultaneous half-exposure phosphor plate and full-exposure conventional screen/film venograms were obtained of 35 patients and compared by using receiver operating characteristic (ROC) analysis. The area under the ROC curve ranged from 0.67 to 0.78 for conventional films and 0.68 to 0.91 for phosphor plates. Group performances on conventional films vs phosphor plates were not statistically different. No statistically significant difference in individual performance with the two techniques was seen in seven of the eight interpreters at the 95% confidence level. The eighth interpreter performed significantly better with phosphor plates than with conventional films. Interpreters with and without specific experience in phosphor plate venography were grouped separately, and performance of the two groups was compared in each technique. No difference in performance was found between the groups when interpreting conventional venograms, but, when interpreting phosphor plate venograms, the group with specific experience performed significantly better than they had with conventional venograms, and significantly better than the other group did at interpreting either conventional or phosphor plate venograms. We conclude that phosphor plate venograms made at a 50% reduction in X-ray exposure are equal to, and may surpass, conventional screen/film venograms for diagnosing acute venous thrombosis of the calf and thigh. We recommend expanding the indications for phosphor plate radiography to include contrast venography of the lower extremities.     

Premature partial closure and other deformities of the growth plate: MR imaging and three-dimensional modeling

PURPOSE: To examine growth plates of the distal femur and tibia with magnetic resonance (MR) imaging to detect bone bridges and other deformities in children. MATERIALS AND METHODS: Thirteen children (nine boys and four girls, aged 5-13 years; mean age, 9.8 years) were referred because of suspected or known bone bridging of the growth plate. Among the 13 patients, 10 had Salter-Harris fractures of the knee or ankle, two had Blount disease, and one had neonatal sepsis. Fat-saturated spoiled gradient-recalled images enabled reconstruction of a three-dimensional model of the growth plate. Patients underwent one to four MR examinations. RESULTS: Nine patients had bone bridging of less than 1% to 39% of the area of the growth plate. On MR images obtained in the growth plate of five patients, a stripe of low signal intensity indicated fracture. On MR images obtained in three patients, intrusions of growth plate cartilage into the metaphysis were seen to increase in depth over time. MR images obtained in four patients showed no bridges. In the two patients who underwent surgery, excellent correspondence was found between MR findings and surgical observations. CONCLUSION: Marked undulation or splitting of the growth plate may occur with fixation of some cartilage in the metaphysis or epiphysis while growth continues. The configuration of the growth plate and bone bridges can be accurately mapped with MR imaging. Treatment planning is facilitated.     

Possibilities of dose reduction in lateral cephalometric radiographs and its effects on clinical diagnostics

OBJECTIVES: The aim of the present study was to determine (1) the absorbed and the exit radiation doses for cephalometric exposures on a phantom head with various exposure settings and image receivers, and (2) the diagnostic image quality for various modalities assessed on cephalometric radiographs of patients. METHODS: The dose measurements for lateral cephalometric radiographs were performed with a semiconductor detector, and also with thermoluminescent detectors and an Alderson phantom. Both the integral and the effective doses were determined. Two radiographs of each patient (n=119) were taken at two different times, one at a low tube potential setting, 75+/-5 kV, and one with a decreased dose. Film-screen systems with speed class 400 and one storage phosphor plate were used. Five observers assessed the radiographs for the visualization of six cephalometric reference points on a three-point scale with -1, 0 and 1. Twenty-seven image pairs were rescored to determine inter- and intrarater reliability. The statistical analysis was done using analysis of variance and Tukey's HSD (honestly significant difference) post hoc test. RESULTS: Increasing the tube potential setting led to an average dose reduction to 83% (integral dose) or to 87% (effective dose). Instead of taking the radiograph at a low tube potential setting (75 kV), a dose reduction of about 15% was feasible at a high tube potential setting (90 kV). A significant difference in reference point visibility existed between film radiographs at low tube potential settings (mean score 0.984) and at high tube potential settings (90 kV, mean score 0.958). For the storage phosphor plates, there was no significant difference to the film-screen combinations at low tube potential and halved milliampere seconds settings. In the second assessment, there was a high degree of agreement (96.6%) compared with the first assessment (unadjusted for random agreement). CONCLUSIONS: As there is only minimal dose reduction at increased tube potential settings, for a dose reduction, it seems to be more useful to use storage phosphor plates at unchanged tube potential and halved milliampere seconds settings compared with the film-screen combination.     

坚硬接骨板固定及取出对骨力学性能的影响

目的：对接骨板固定及取出后固定骨段的力学性能变化进行观察分析．方法：实验用新西兰兔２８只，４只对照，２４只在左胫骨行不锈钢板固定，其中２０只动物术后２个月取出钢板，并在取钢板当时及取钢板后１、２、３和４个月分别有４只动物处死，另有４只动物于内固定后６个月处死，取完整胫骨作力学测试．结果：坚硬接骨板固定可诱发严重的局部骨质疏松，导致固定骨段力学性能下降．接骨板取出后固定骨段力学性能可逐步恢复，但恢复过程较缓慢．结论：接骨板取出后的骨强度恢复延迟，可能是固定骨段发生再骨折的潜在原因．     

多功能带锁髓内钉与双钢板治疗胫骨近端关节外骨折的临床效果比较

目的比较多功能带锁髓内钉(TINMI)、双钢板治疗胫骨近端关节外骨折的临床效果。方法收集笔者医院2009年3月~2014年7月治疗的胫骨近端关节外骨折患者80例,根据采用内固定的不同分为TINMI组、钢板组,TINMI组35例,其中男性20例,女性15例;平均年龄(45.7±7.9)岁。致伤原因:道路交通伤18例,高空坠落伤12例,其他伤5例。钢板组45例,其中男性25例,女性20例;平均年龄(48.3±8.1)岁。致伤原因:道路交通伤24例,高空坠落伤15例,其他伤6例。两组患者一般资料具有可比性,统计两组患者手术时间、术中出血量、术中透视次数、平均骨折愈合时间、部分负重时间、完全负重时间、骨折愈合优良率、术后并发症情况等。结果两组患者均获得1年以上随访,两组患者手术时间、术中出血量、术中透视次数、部分负重时间差异无统计学意义(P0.05),TINMI组患者平均骨折愈合时间、完全负重时间明显短于钢板组(P0.05),TINMI组骨折愈合优良率为82.9%,钢板组患者骨折愈合优良率为62.2%,差异有统计学意义(P0.05),TINMI组患者总并发症率为14.3%,钢板组患者优良率为24.4%,差异无统计学意义(P0.05)。结论 TINMI与钢板治疗胫骨近端关节外骨折手术操作复杂程度类似,但TINMI具有骨折愈合时间及完全负重时间短、骨折愈合优良率高、并发症少等优点,值得临床推广     

犬下颌骨骨折内固定术后应力遮挡效应的实验研究

 目的 对下颌骨骨折内固定术后拆除小型接骨板前后应力遮挡效应进行动物实验研究,为下颌骨骨折愈合后内固定材料的远期处置提供理论依据。 方法 18只犬中3只犬即刻处死测定下颌骨骨密度和最大断裂力,该组设为正常组。其余15只犬人为造成双侧下颌骨骨折并行双侧小型接骨板固定（每只犬右侧为实验侧,左侧为对照侧）。固定2个月后,3只犬处死双侧取板测定骨密度和最大断裂力,该组设为0月组;其余12只犬右侧（实验侧）小型接骨板全部取出,取板后再经过1、2、3、6个月后各处死3只犬取左侧（对照侧）板,分别设为1、2、3、6个月组。比较左右两侧下颌骨在骨密度、最大断裂力上的异同。 结果 1、2、3、6个月组实验侧和对照侧骨密度值比0月组高（ P <0.05）,实验侧和对照侧比较各组之间差异无统计学意义。6个月组对照侧的骨密度值与正常组比较较低,差异有统计学意义（ P <0.05）。1、2、3、6个月组实验侧和对照侧与0月组比较最大断裂力值较高（ P <0.05）。实验侧和对照侧比较,各组间最大断裂力差异均无统计学意义; 6个月组对照侧与正常组比较最大断裂力值较低,差异有统计学意义（ P <0.05）。 结论 随着内固定时间的增加,在本实验中出现了应力遮挡效应。另外在内固定3个月时下颌骨实验侧和对照侧骨密度和最大断裂力值较高,说明内固定3个月时拆除接骨板可能最有利。     

The distal femoral and proximal tibial growth plates: MR imaging,three-dimensional modeling and estimation of area and volume

Objective To explore how the size of the growth plate changes with age using three-dimensional (3D) models of the distal femoral and proximal tibial growth plates in pediatric patients.Design and patients We retrospectively created 3D models of the normal unaffected distal femoral (n=20) and proximal tibial (n=10) growth plates in 14 patients (9 males, 5 females) age range 3.8–15.6 years who were referred for evaluation of premature partial closure of the growth plate or hyaline cartilage abnormality. All patients had one or more 3D fat-suppressed spoiled GRASS sequence from which models were made of normal growth plates. Total projected area was estimated from standardized maximum intensity projection (MIP) views, and volume was computed from the entire model. We also included the total projected area of the distal femur (n=7) or proximal tibia (n=8) in 11 patients (8 males, 3 females, 5–13 years) who had previously been evaluated for bone bridging.Results The 3D femoral and tibial growth plate anatomy was displayed. Femoral growth plate area varied from 804 mm² to 3,463 mm². Femoral physeal cartilage volume varied from 2.1 cm³ to 12.6 cm³. Tibial growth plate area varied from 736 mm² to 3,026 mm². Tibial physeal cartilage volume varied from 1.9 cm³ to 13.2 cm³. The growth plate area values appear to increase linearly with increasing age.Conclusions The distal femoral and proximal tibial physeal plates have complex anatomy. Both area and volume of the growth plates appeared to follow a linear increase with age and reached a plateau in adolescence, although there was some scatter. Area appears to have less measurement variability than volume, and may be a more reliable predictor of growth plate tissue quantity.     

载万古霉素缓释钢板对兔胫骨金黄色葡萄球菌感染模型预防作用的研究

目的探讨载万古霉素缓释钢板在兔胫骨金黄色葡萄球菌感染模型中的预防作用。方法新西兰白兔64只，制备胫骨中段单侧皮质横断骨折模型，分别置入载万古霉素缓释钢板和普通不锈钢钢板，注射金黄色葡萄球菌，比较两种钢板对兔胫骨金葡菌感染模型的预防作用。结果64只兔共存活48只，置入载万古霉素缓释钢板的实验组兔24只中感染2只，普通钢板对照组24只中感染14只，两组之间差异有统计学意义（P=0．001，P〈0．05）。两组之间白细胞总数、血沉、C反应蛋白差异有统计学意义（P〈0．05）。结论载万古霉素缓释钢板在兔胫骨金黄色葡萄球菌感染模型中有较明确的预防作用。     

水升华器用多孔板的物理特性研究

目的探讨水升华器的关键部件—多孔板的研制方法,并对多孔板的主要物理特性参数进行研究。方法在对水升华器用多孔板技术指标进行分析的基础上,利用粉末烧结技术,使用不同的材料,研制出了多孔板。设计了多孔板物理特性测试装置,对所研制的多孔板进行了较全面的物理特性测试。结果获得了影响多孔板性能的主要因素,为水升华器性能测试和全面建立多孔板的研制规范及优化多孔板的物理性能参数打下基础。结论采用粉末烧结技术研制的多孔板的特性满足水升华器的性能要求。     

In-situ force plate calibration: 12 years’ experience with an approach for correcting the point of force application

Force plates are common assessment tools used in biomechanics to measure ground reaction forces during motion capture or strength exercises. While the accuracy of the resulting kinetic data is critical for accurate gait analysis, factors such as plate mounting are thought to influence the measured point of force application (PFA) of the ground reaction forces. The aim of this study was therefore to present an accurate in-situ PFA calibration method. In addition, the approach was evaluated by examining the required PFA corrections over a period of ten years, which included plate remounting and a change of foundation.The in-situ PFA calibration was performed on six plates by assessing the locations of up to 98 points of force application per plate using an instrumented pole. Application of the in-situ PFA calibration approach reduced the root mean square errors by up to approximately 60% compared to the manufacturers calculation. Correction coefficients were strongly dependent on the individual platform as well as the location of the applied force on the plate. Remounting of the plates altered the plate coefficient corrections considerably, while changes over time were notable but not as extensive. We therefore recommend that plates should be recalibrated after remounting, but also at least every 5 years, in order to ensure the preservation of an accurate PFA.     

两种钢板治疗Danis-Weber /AO B型外踝骨折的疗效比较

 目的 比较外侧中和钢板及后外侧抗滑钢板内固定治疗Danis-Weber/AO B型闭合性外踝骨折的疗效。方法 选择2012-03至2015-06医院收治的Danis-Weber/AO B型闭合性外踝骨折44例,根据患者意愿分为外侧中和钢板固定组(中和组,24例),后外侧抗滑钢板固定组(抗滑组,20例)。中和组骨折解剖复位,选取合适的拉力螺钉自前向后垂直于骨折线置入,腓骨外侧解剖钢板固定于腓骨外侧合适的位置;抗滑组骨折解剖复位,钢板放置于腓骨后外侧,使用合适的螺钉内固定,最少随访1年。术后1年根据美国足踝外科协会后足踝评分系统(AOFAS)进行功能评价,记录并发症。结果 术后1年中和组和抗滑组AOFAS评分分别为93.7±6.1和94.5±6.0,两组比较没有统计学差异(P=0.37)。中和组7例(29.3%)发生并发症,抗滑组3例(15.0%)发生并发症,其中1例腓骨肌腱病,两组并发症发生率比较,差异无统计学意义(P=0.31)。结论 对旋后外旋型损伤的Danis-Weber/AO B型外踝骨折进行手术治疗,与传统的外侧钢板固定技术比较,抗滑组手术效果与之相当,并发症发生率无差异,两种技术均安全有效,值得推广。     

Comparison of cone beam CT scans with enhanced photostimulated phosphor plate images in the detection of root fracture of endodontically treated teeth

Objectives:

Two-dimensional intraoral radiography is the most common tool for diagnosing root fractures (RFs). Cone beam CT (CBCT) is widely used to depict RFs in endodontically treated teeth. Beam hardening and other artefacts caused by gutta percha may result in an incorrect diagnosis when using CBCT only. A comparison of two CBCT machines with photostimulated phosphor (PSP) plate images enhanced with the equalization tool was carried out to detect RFs in endodontically treated teeth.

Methods:

66 roots were collected, decoronated and treated endodontically using the same technique with gutta percha. 33 of these roots were randomly selected and fractured; the 2 root fragments were glued together with 1 layer of methyl methacrylate and placed randomly in 8 prepared beef rib fragments. Large fields of view (FOVs) were acquired with one CBCT unit and small FOVs with the second CBCT unit. Periapical radiographs (using intraoral PSP plates) were also acquired. A contrast enhancement tool was used when evaluating the PSP plate images.

Results:

Small FOV images had significantly higher accuracy (area under the receiver operating characteristic curve) and sensitivity in detecting RFs than PSP plates and large FOV images. The specificity of the enhanced PSP images was higher than, although not significantly higher than, the small FOV images and was significantly higher than the large FOV images.

Conclusions:

CBCT small FOVs should be acquired for depicting RFs of endodontically treated teeth. Images obtained using PSP plates had the lowest rate of false-positive results and their use can save the patient a radiation dose.     

MR imaging of fractures of the growth plate

In order to assess whether MR imaging could be used to evaluate posttraumatic abnormalities of the growth plate cartilage, 28 MR imaging examinations of 26 physeal fractures were performed from 4 days to 2 years after injury. Twelve patients were studied within 6 months of the fracture. MR imaging changed the Salter-Harris classification in six. Interruption of the growth plate detected on T2-weighted images was associated with subsequent growth anomaly in six of eight patients. Horizontal fracture of the physis without interruption was associated with growth disturbance in only one of four patients. Sixteen growth plates were studied beyond 6 months after injury. Twelve had physeal bars and abnormal growth. Of four patients without physeal abnormality on MR imaging, two had normal growth and two had mild deformity. Our results show that MR imaging defects abnormalities in the cartilage that are associated with subsequent growth disturbances and provides accurate mapping of physeal bridging and associated growth abnormalities that have already occurred.     

34例SARS患者影像随访观察

目的:探讨SARS患者肺纤维化的转归情况并随访观察其胸部及髋关节影像学表现。方法:对在我院住院治疗的34例SARS患者进行的影像学检查随访观察1年,随访内容包括摄胸部X线正侧位、骨盆正位片及CT扫描检查。结果:34例SARS患者中18例在住院时期肺部有不同程度的纤维化改变。其中15例重症SARS病例中12例住院时期肺部有纤维化改变。19例普通型SARS中,6例并发肺纤维化。两者比较,差异有显著性意义(P<0.05)。出院时9例(27%)患者存在肺纤维化。随访1月,4例(12%)SARS患者两肺见纤维条索状影,粗细不均,但与前片比较均有吸收好转。随访3月,仅2例(6%)见两肺纤维条索影,其余2例病灶完全吸收。随访6月及12月,1例(3%)见纤维条索影,两肺纹理增重。1年随访中未观察到股骨头缺血坏死的发生。结论:肺纤维化是SARS患者较常见的并发症,重症SARS患者较普通型患者更易发生肺纤维化,老年和重症SARS患者合并肺纤维化的程度较重,其肺纤维化吸收慢、时间长。未见股骨头缺血坏死的征象。     

高电压胸部摄影诊断和防护效果研究

作者以体模实验为基础。测定了不同管电压拍摄胸片时的病人剂量，考察了提高管电压对胶片影像质量的影响，结果表明，使用高电压拍摄胸片比使用低电压有利于降低病人剂量，在增加影像信息量，提高肋骨阴影区和纵膈区灶检出率方面更有较大优越性，此外，使用高电压技术不家利于延长Ｘ射线管的使用寿命。     

Dose-image optimisation in digital radiology with a direct digital detector: an example applied to pelvic examinations

In diagnostic radiology increasing attention has been focused on dose reduction while maintaining a clinically good image quality. With the use of digital detectors balancing dose vs image quality is done differently than in film-screen radiography, since dose and image brightness are uncoupled in digital imaging. In this study a new direct digital detector (flat-panel detector) was used in a dose-image optimisation of a simulated pelvic examination. X-ray images were taken with a direct digital detector (DDD), of the pelvic of a phantom using varying tube current (varying stochastic noise). The entrance surface dose was measured for each image. These images were scored by two radiologists according to EU guidelines. A dose comparison was made with an older PCR system (storage phosphor plates). With decreasing tube current the noise in the images increased and the image with the lowest dose and still acceptable image quality was identified. The results showed that the entrance surface dose using the DDD decreased from 1.4 mGy (PCR value) to 0.48 mGy (DDD standard settings). Through the optimisation the dose could be further decreased to 0.24 mGy while still maintaining an acceptable image quality. A substantial dose reduction was obtained with this new direct digital detector. This simple but efficient optimisation approach is easily applicable to other examinations and both DDD and storage phosphor plate detectors.     

憎水涂层多孔板对水升华器散热性能影响的实验研究

目的 探讨水升华器用憎水涂层多孔板的实现方法，并对所研制的憎水涂层多孔板进行实验研究。方法 利用Teflon溶液和特制的双疏涂层溶液对多孔板进行憎水涂层处理，并对所研制的憎水涂层多孔板进行物理特性测试。重新设计了水升华器实验件，对涂覆憎水涂层的多孔板、对水升华器散热性能的影响进行了实验研究。结果 憎水涂层多孔板的水滞留能力显著提高，但其渗透压降也不同程度地增加。两种涂层板的散热性能有所不同。采用双疏涂层溶液涂覆的多孔板相对好一些。结论 在对Teflon和双疏涂层溶液的涂覆参数及工艺进行优化后，憎水涂层多孔板可以提高水升华器的工作性能。     

Sonography of plantar plates in cadavers: correlation with MRI and histology

OBJECTIVE: The purpose of our study was to describe the sonographic appearance of the lesser metatarsal plantar plates in cadavers and to correlate these findings with MRI and histology. MATERIALS AND METHODS: Six soft-embalmed cadaveric feet (74-92 years old; two male, one female) were imaged with sonography and MRI. Tear dimensions of the plantar plate were recorded in the long and short axes. Orthopedic surgeons directly inspected the plantar plates before removing samples for histologic correlation. One young fresh cadaver was imaged with sonography before histologic assessment. RESULTS: The normal plantar plate appearance on sonography was a slightly echoic, homogeneous, curved structure. At direct inspection, a tear was present in 23 (96%) of 24 of the lesser plantar plates in the soft-embalmed feet. This direct inspection correlated with sonography detecting 23 tears correctly and MRI, 22 tears. Both sonography and MRI falsely reported one tear, but MRI also failed to detect one tear. Histologically, the abnormal plantar plate showed loss of the normal dense regular tissue and replacement with vessels, hydropic tissue, and a mixture of loose connective tissue and dense irregular connective tissue. CONCLUSION: Sonography, being noninvasive, shows promise as an imaging tool of the plantar plate. With ongoing research in this area we hope to determine the reliability and significance of such a technique in the evaluation of the plantar plate.