Computed tomography assisted repair of a central tarsal bone slab fracture in a horse

A 13‐year‐old Quarter Horse gelding was presented for repair of a central tarsal bone fracture. Radiographs showed a single large nondisplaced sagittal slab fracture; however, computed tomography (CT) revealed an additional small, displaced central tarsal bone fragment. The complex fracture was repaired, under the same anaesthetic period as the CT examination, using the CT hard copies images, intraoperative fluoroscopy and radiographs. The horse recovered well and after rehabilitation showed no residual lameness at work. Computed tomography was instrumental in achieving precise screw placement and successful fracture repair.     

Palmar or plantar process fractures of the distal phalanx in riding horses: 22 cases (1994–2003)

No case series exists in the literature describing palmar/plantar process fractures (PPFs) of the distal phalanx in a nonracehorse population. We aim to describe the distribution of these injuries, together with their clinical, radiographic and scintigraphic features. In a retrospective case study, horses were selected based on radiographic evidence of a PPF. Data were collected relating to clinical and lameness examination, radiography, scintigraphy, management and follow‐up information. Oblique and flexed oblique radiographic views of the distal phalanx are the most sensitive in detecting PPFs of the distal phalanx and this study concluded that fractures of palmar or plantar process are likely to be missed in horses showing mild lameness if oblique radiographic views of the palmar process are not included.     

MRI has limited agreement with CT in the evaluation of vertebral fractures of the canine trauma patient

Complete assessment of vertebral trauma in dogs currently requires CT and MRI for evaluation of the osseous and soft tissue structures that contribute to vertebral stability. Some studies in people have suggested that MRI may be sensitive and specific at detecting vertebral fractures making this potentially a single modality that could be used in spinal trauma evaluation. This study aimed to assess the ability for observers to evaluate vertebral fractures using MRI when compared to CT, which was used as the reference standard. Twenty‐nine dogs with previously diagnosed acute vertebral fractures and four dogs with no vertebral fracture that had undergone sequential CT and MRI were included into the study. One hundred twenty‐eight vertebrae were evaluated for the presence of fractures. Imaging studies were read by two observers blinded to the history. While both observers had similarly high sensitivity and specificity for simple detection of any fractured vertebrae, interobserver agreement was only moderate (κ = 0.584). When evaluations were specifically limited to detection of structurally unstable fractured vertebrae both observers showed improved specificity and interobserver agreement became substantial (κ = 0.650). Complete agreement for exact fracture location between MRI and CT results was only achieved in 14.3‐32.6% of fractured vertebra with up to 79% of fractures being missed in some vertebral structures. This suggests that although MRI may be able to detect the presence of fractured vertebrae, it is not able to replace CT for the complete evaluation of the traumatized spine and documentation of fracture morphology.     

Computed tomographic diagnosis of incomplete palmar cortical (fatigue) fracture of the third metacarpal bone in two young adult endurance horses

Two young adult endurance horses were presented for investigation of sudden-onset forelimb lameness during competition. Clinical examination revealed a severe forelimb lameness and pain on palpation of the proximal palmar metacarpal area. Initial radiographic survey of the affected forelimb was unremarkable in both cases. A week of box rest resulted in only a mild improvement in the lameness. A second radiographic examination did not reveal any significant abnormalities. In both cases, scintigraphic examination was suggested, but was declined by the owner, and the lameness had significantly improved after local infiltration of 3 mL of anaesthetic solution in the proximal suspensory region. Radiographic and ultrasonographic examinations of the carpus and proximal suspensory region were unremarkable in Case 2. Case 1 had increased thickness of the medial lobe of the proximal aspect of the suspensory ligament. A computed tomographic examination was performed and an incomplete longitudinal (fatigue) fracture of the proximal third metacarpal bone was detected. After 8 months of box rest and rehabilitation, re-examination revealed resolution of the lameness in both cases. Advanced diagnostic imaging should be considered in young endurance horses with severe lameness during competition or training, in which radiographic and ultrasonographic examinations are unremarkable or do not explain the severity of the lameness. Computed tomography imaging is considered a useful diagnostic imaging technique to detect incomplete longitudinal palmar metacarpal cortical (fatigue) fractures due to its ability to provide excellent bone detail.     

Resuscitation attempts in a foal with sudden cardiac arrest in the early recovery period

A 3‐month‐old female Warmblood foal, weighing 150 kg, was presented to the Equine Clinic of the University of Hannover with a fracture of the ulna (type 5 fracture of the olecranon). Anaesthesia was induced with midazolam and ketamine after sedation with xylazine and maintained with isoflurane. Anaesthesia was uneventful until cardiac arrest occurred in the early recovery period. Cardiopulmonary resuscitation (CPR) was performed with chest compressions and electrical defibrillation. During resuscitation palpebral reflexes and spontaneous breathing returned but ventricular fibrillation could not be converted to sinus rhythm by transthoracic defibrillation of the heart by electrical shock.     

Elastic_Brittle Fracture Analysis of Micro_Crackin Concrete Loaded by Stretching Stresses

The concrete is a typical brittle material.The fracture and propagating failure of the micro-crack in loaded concrete are very important problem in civil engineering.In this paper,from the equilibrium differential equations and failure criterion,the elastic-brittle static fracture analysis of the plane stress micro-crack in concrete loaded by stretching stresses was done near crack line.The relations between the stretching stresses and the length of brittle fracture zone on the crack line were obtained.     

Fracture Growing Modal Based on FEM

A noval frature growing model based on FEM and degrading rules of materials was proposed,and many disadvantages of existing model were improved with the new modal , dimensional problem was analysed and satisfactory results was gained.     

管道环焊接头断裂评定方法分析

管道是石油和天然气的主要运输工具,春焊接质量对管道的安全可靠性有较大影响。管道环焊接头的断裂评定,对于管道系统的安全动物真有重要意义。介绍了欧美等国家有关管道环焊接头断裂评定方面的理论研究和工程方法的进展,讨论了各种评定方法之间的差异,目的在于为管道焊接施工提供科学依据和理论指导。     

螺旋焊管与直缝焊管裂纹断裂分析

根据最大位应力理论,分析了焊管在受内压及裂余应力的作用下,焊缝区Ⅰ／Ⅱ混合型裂纹开裂角θ０与裂纹角β的关系,并分析限具有不同裂纹缺陷时,螺旋管与直缝管的断裂破坏强度。     

断裂错动与水作用下的地层位移及应力变化

[目的]在断裂活动和地下水位变化条件下,对地裂缝上下盘地层的沉降位移与应力变化进行分析,为深入研究地裂缝的形成机理提供参考。[方法]以北京市高丽营地区地裂缝为研究背景原型,基于其活动特征,分析了该地裂缝的发育与断裂构造及地下水水位变化之间的关系,并运用数值模拟方法分别研究了两种诱因作用下模型地层的沉降位移及土体内部应力的变化规律。[结果]断裂错动作用下,地裂缝上盘土层的沉降变形响应程度大于下盘,地表竖向位移变化曲线近似呈反"S"形态,且上盘应力降低区的范围大于下盘应力增强区的范围;地层沉降量随地下水位的下降而不断增加,其土体应力变化曲线呈"中心对称"。[结论]断裂两侧附近的土体沉降位移和应力变化的差异较明显,且差异沉降与水位降深呈正相关,地下水位下降易诱发地裂缝的影响范围是上盘45m和下盘35m,研究成果可为地裂缝灾害地区的防灾减灾提供科学的理论依据。