通用型脊柱内固定系统稳定性的生物力学评价

目的　评价通用型脊柱内固定系统经椎弓根内固定装置的生物力学稳定性。　方法取 12具正常成人新鲜尸体T12 ～S3 节段脊柱标本 ,制成L2 3 、L4 5滑脱模型 ,测试标本在正常、滑脱、通用型脊柱内固定系统 (generalspinesystem ,GSS)与SOCON固定后、疲劳试验后、GSS与SOCON翻修后、再次疲劳试验后 6种请状况下的三维运动状况 ,比较各个工况数据的差异。　结果　L2 3 节段 ,正常状态前屈运动范围平均值为 8 3° ;制成滑脱标本后 ,运动范围平均值为 14 7° ;SOCON固定后 ,节段运动范围减至 3 0°,比正常状态的运动范围减小 ,差异有显著性意义 (P <0 0 5 ) ,说明SOCON固定后可产生明显的即刻稳定作用。疲劳试验后节段运动范围平均值为 3 6°,与正常状态比较 ,差异有显著性意义 (P <0 0 5 ) ,说明经过疲劳试验SOCON固定仍有良好的稳定作用。L4 5节段 ,正常状态前屈运动范围平均值为 8 6°;制成滑脱标本后 ,运动范围平均值为 13 7° ;GSS固定后 ,节段运动范围减至 3 2°,该节段的稳定性得到加强 ,运动范围比正常状态时还要小 ,差异有显著性意义 (P <0 0 5 ) ,说明GSS固定后可产生明显的即刻稳定作用。疲劳试验后节段运动范围平均值为 3 7°。与正常状态比较 ,差异有显著性意义 (P 相似文献   

Properties of internal pilots with the univariate approach to repeated measures

Uncertainty surrounding the error covariance matrix often presents the biggest barrier to achieving accurate power analysis in the 'univariate' approach to repeated measures analysis of variance (UNIREP). A poor choice gives either an overpowered study which wastes resources, or an underpowered study with little chance of success. Internal pilot designs were introduced to resolve such uncertainty about error variance for t-tests. In earlier papers, we extended the use of internal pilots to any univariate linear model with fixed predictors and independent Gaussian errors. Here we further extend our exact and approximate results to UNIREP analysis. For a fixed treatment effect, the inaccuracy in a power calculation depends only on the ratio of the true variance to the value used for planning. The greater complexity of repeated measures requires generalizing misspecification of error variance to the misspecification of the eigenvalues of the error covariance. We recommend approximating the misspecification in terms of the first and second moments of the eigenvalues, for both fixed sample and internal pilot designs. We also describe an unadjusted approach for internal pilots with repeated measures. Simulations illustrate the fact that both positive and negative properties in the univariate setting extend to repeated measures analysis. In particular, internal pilots allow maintaining power or reducing expected sample size when the covariance matrix used for planning differs from the true value. However, an unadjusted approach can inflate test size, at least with small to moderate sample sizes. Hence new, adjusted methods must be developed for small samples. At this time, we caution against using an internal pilot design with repeated measures without first conducting simulations to document the amount of test size inflation possible for the conditions of interest.     

New paradigms for nutrient control of genome translation

Organisms respond adaptively to changing environmental conditions by altering genome expression. Translational control of gene expression by nutrients and metabolites is one of the most robust biologic mechanisms that enable rapid alterations in the cellular proteome in response to changes in the local environment. Recently, investigators have identified new mechanisms for nutrient control of translation in mammals; evidence supports the conservation of translational control mechanisms in eukaryotes that heretofore had only been demonstrated in prokaryotes.     

Discrepancy between myocardial ischemia and luminal stenosis in patients with left internal mammary artery grafting to left anterior descending coronary artery

BACKGROUND: Left internal mammary artery (LIMA) grafting to the left anterior descending artery (LAD) is known to have long-term patency. However, myocardial ischemia in the territories supplied by LIMA to LAD is still demonstrated. The aim of this study is to examine the relationships between the extent, location, and clinical outcome of myocardial ischemia in LAD territories (ILAD) by use of myocardial perfusion imaging (MPI) and angiographic characteristics of such a bypass conduit. METHODS AND RESULTS: We studied 38 consecutive patients with prior coronary artery bypass grafting who showed stress-induced ischemia in LIMA to LAD territories by MPI single photon emission computed tomography between the years 1996-2000. All patients underwent quantitative coronary angiography within 6 months of the nuclear study. Single photon emission computed tomography parameters of ILAD were assessed by location (septum, apex, anterior, and anterolateral) and included extension score (1-4 per patient), severity score (0-3 per territory), and total sum score. LIMA to LAD quantitative coronary angiography parameters included minimal lumen diameter, lesion length, reference diameter, and diameter stenosis (percentage). LAD and LIMA diameters and ratio (in normal segments) were determined within 10 mm proximal and distal to the anastomotic site. The study group was compared with 18 control subjects without ischemia or stenosis treated with LIMA to LAD. The patients were followed up for cardiac death at an interval of 3.2 +/- 1.5 years from the time of MPI testing. The patients' mean age was 66 +/- 12 years (31 men and 7 women); the mean period after surgery was 6.2 +/- 1.5 years. The ILAD distribution was as follows: septum, 12 (32%); apex, 20 (52%); anterior, 24 (63%); and anterolateral, 18 (47%). The mean extension score was 1.9 +/- 1.0, and the mean total sum score was 3.4 +/- 2.3. Of 38 patients with ILAD, only 17 (45%) had greater than 50% luminal stenosis (2 LIMA and 15 anastomosis or distal). Among clinical variables during stress testing, the prevalence of angina was significantly higher in the luminal stenotic patients versus patients without stenosis (P =.04). A significant correlation was found between anterior wall ischemia and reference diameter (r = -0.7, P =.002) and between total sum score and minimal lumen diameter (r = -0.48, P =.05). Of note, the LAD-to-LIMA ratio was significantly lower in patients with ILAD and without luminal stenosis compared with the control group (0.73 +/- 0.16 vs 0.87 +/- 0.15, P =.004). Cardiac death occurred in 8 patients (21%), 5 patients with luminal stenosis versus 3 patients without stenosis (P = not significant). CONCLUSIONS: In patients with LIMA to LAD anastomosis, myocardial ischemia could occur even without angiographic luminal stenosis and apparently reflects a mismatch between LAD and LIMA diameters at distal anastomotic sites. Regarding the similar prevalence of cardiacdeath, invasive evaluation and aggressive treatment are recommended in all patients with ischemia in LIMA/LAD territories.     

Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative

AIM: To improve the accuracy and completeness of reporting of studies of diagnostic accuracy in order to allow readers to assess the potential for bias in a study and to evaluate the general isability of its results.METHODS: The standards for reporting of diagnostic accuracy (STARD) steering committee searched the literature to identify publications on the appropriate conduct and reporting of diagnostic studies and extracted potential items into an extensive list. Researchers, editors, and members of professional organisations shortened this list during a 2 day consensus meeting with the goal of developing a checklist and a generic flow diagram for studies of diagnostic accuracy.RESULTS: The search for published guidelines about diagnostic research yielded 33 previously published checklists, from which we extracted a list of 75 potential items. At the consensus meeting, participants shortened the list to a 25-item checklist, by using evidence whenever available. A prototype of a flow diagram provides information about the method of recruitment of patients, the order of test execution and the numbers of patients undergoing the test under evaluation, the reference standard, or both.CONCLUSIONS: Evaluation of research depends on complete and accurate reporting. If medical journals adopt the checklist and the flow diagram, the quality of reporting of studies of diagnostic accuracy should improve to the advantage of clinicians, researchers, reviewers, journals, and the public.     

关节镜辅助治疗桡骨远端关节内骨折

Objective To investigate the role of arthroscopy in the treatment of intra-articular distal radius fractures. Methods Twelve cases of intra-articular distal radius fractures treated from 2004 to 2007 were reviewed. In these cases, open reduction and internal fixation were performed with the assistance of wrist arthroscopy to observe the alignment of the articular surface. CT scan was obtained postoperatively to evaluate joint alignment, radial height, volar tilting and radial inclination. Recovery of the wrist function was also followed. Results The average postoperative follow up period was 24 months. None of the 12 cases was found to have any "step" appearance of the articular surface of the wrist. X-ray measurement showed radial height averaged 12 mm (7 to 15 mm), volar tilting averaged 5° (1° to9°) and radial inclination averaged 20 °(14° to28°). Range of motion of the wrist joint achieved 33° of flexion on average ( 18° to 42°) and 38° of extension on average (21° to 42°). Six cases had mild pain during motion. According to Gartland / Werley' s criteria, the result was excellent in 5 eases and good in 7. Conclusion Arthroscope-assisted treatment of intra-articular distal radius fractures can avoid "step" appearance of the articular surface of the wrist, thus achieve maximal functional recovery of the wrist.     

Internal hernia traversing the lesser sac

Congenital internal hernias are a rare cause of small bowel obstruction in adults and often present with complications. A high index of suspicion, occasionally aided by appropriate radiological imaging, may lead to early surgical intervention and reduce morbidity and mortality. A 25‐year‐old man presented with colicky abdominal pain and minimal signs on abdominal examination. Computed tomography showed features of a small bowel obstruction and prompted surgery. This revealed an internal hernia traversing the lesser sac through defects in both the gastrocolic ligament and lesser omentum. A gangrenous segment of small bowel incarcerated in the lesser omentum was resected and the patient made a full recovery. The published reports relating to lesser sac hernias are reviewed and features that may lead to early diagnosis identified.      

Subacute hypoglossal nerve paresis with internal carotid artery dissection

OBJECTIVES: To describe a case of an isolated hypoglossal nerve palsy in a patient with a spontaneous internal carotid artery dissection (ICAD). This condition is a well-recognized cause of cerebral ischemic stroke in patients younger than 45 years of age. Isolated cranial nerve neuropathy is a rare presentation. More common manifestations include incomplete hemiparesis, hemicrania, Horner syndrome, cervical bruit, pulsatile tinnitus, and multiple cranial nerve palsies. METHODS: A comprehensive literature search (Ovid, MEDLINE) for the presentation, diagnostic evaluation, treatment, and outcome of patients with internal carotid artery dissection was performed. RESULTS: A 43-year-old man presented with a 3-week history of mild dysarthria. There was no history of craniocervical trauma. The physical examination revealed an isolated left hypoglossal nerve paresis. Magnetic resonance imaging and angiography findings were consistent with a left skull base ICAD. The patient was successfully treated with anticoagulation therapy. The current rate of cranial nerve involvement is estimated at 10% of all ICADs. This is the second report of isolated hypoglossal nerve palsy without hemicrania in a case of atraumatic ICAD. CONCLUSIONS: Patients with an ICAD infrequently present to the otolaryngologist because of its head and neck manifestations. It is crucial to recognize atypical findings and to perform an accurate and prompt diagnostic evaluation. The foundation of treatment is aggressive anticoagulation, with surgical or radiologic intervention reserved for cases demonstrating life-threatening progression.     

Lethal post-tonsillectomy hemorrhage

Background: Post-tonsillectomy hemorrhage (PTH) seems to be a rare but unavoidable complication. Due to the frequency of performed tonsillectomies, it can be estimated that a certain amount may result in a lethal outcome. This study was undertaken to evaluate the clinical features of these rare cases. Material and methods: Retrospective case series of five patients with lethal post-tonsillectomy hemorrhage are reported after they had undergone tonsillectomy by four different surgeons. The relevant literature was reviewed. Results: The youngest patient was 42 months and the oldest almost 13 years old. All patients were male. Three patients had left the hospital against surgeon’s recommendation 5 days following tonsillectomy. Preceding episodes of bleeding prior to the lethal bleeding occurred in two patients. Lethal PTH occurred in four patients within 5–9 days, the latest bleeding 39 days after surgery. In the literature, lethal PTH was described for eight patients since 1958. The youngest patient was 4 years, the oldest 18 years old (mean: 8.6 years; median: 6.5 years). In three patients, lethal PTH occurred on the day of surgery and the latest bleeding 54 days after surgery. Conclusion: Due to the paucity of reports, little reliable information can be obtained from the literature. It remains unclear, whether or not this reflects the true incidence of this complication. The experience with the five reported cases suggests, that immediate surgical treatment may have avoided lethal outcome in most cases. Therefore, a close postoperative follow-up is advisable to detect any episode of bleeding as soon as possible which should be referred to a specialist. Certainly, the collected data do not suffice to establish general guidelines, indicating that further collection of cases is required to assess characteristics of lethal PTH.     

Electroporation therapy for head and neck cancer including carotid artery involvement

OBJECTIVES: Electroporation therapy with intralesional bleomycin (EPT) is a novel, technically simple outpatient technique in which high-voltage electric impulses delivered into a neoplasm transiently increase cell membrane permeability to large molecules, including cytotoxic agents, causing localized progressive necrosis. Unlike many laser ablation methods, EPT can treat bulky tumors (>2 cm) with complete penetration. Our recent publication confirms an excellent response rate in the use of EPT in a clinical trial. STUDY DESIGN, PATIENTS, AND METHODS: Following our initial prospective study report in 1998, we have followed our entire initial cohort (10 patients) of patients with head and neck cancer beyond 24-months follow-up. Additionally, we have used this approach to treat four additional patients (total: 9 males/5 females) with upper aerodigestive tract squamous cell carcinoma, including three with internal carotid artery (ICA) involvement up to or within the skull base. Two patients underwent preoperative balloon test occlusion with cerebral perfusion studies followed by carotid embolization. EPT was then done safely at least 2 weeks later to avoid the temporary hypercoagulable state. RESULTS: Within the overall cohort (14 patients) 6 patients had a complete response, 6 had a partial response, and 2 did not respond (overall 85.7% response rate). Both patients with ICA involvement had a partial or complete response to treatment; neither patient had a hemorrhagic or neurologic complication. Overall, 13 of the 14 patients were treated for persistent or recurrent head and neck cancer. Two of the four patients with early recurrent stage tumors had no evidence of recurrence after EPT with an average follow-up of 31.5 months. The overall early stage tumor group had four complete responders out of five (80%). On the contrary, only 2 of 9 patients with advanced recurrent stage tumors were disease-free at 18 months. Morbidity was low for early stage tumors, but higher for advanced tumors with complications, including poor wound healing, dysphagia, and osteomyelitis. There were no treatment-related deaths. CONCLUSION: We found EPT to be safe and efficacious in patients with head and neck cancer, even with internal carotid artery involvement. Patients with early stage recurrences have the potential for prolonged survival beyond 2 years without the morbidity of surgery and radiation or toxicity of systemic chemotherapy. Because of its superb access qualities even for bulky tumors, EPT is a potential method of delivery for other tumoricidal agents such as in genetic-altering schemes.