具有解剖基下颌的人头模型撞击损伤的有限元研究

目的 建立具有解剖基下颌的人体头部有限元模型。探讨此模型以不同速度正面撞击的响应过程,研究其损伤的生物力学机理。方法 根据人体下颌骨的螺旋CT扫描图像,利用三维重建、图像处理和网格划分技术,建立人体下颌骨的三维有限元模型,通过关节和经过修改的混合Ⅲ型假人头部模型相连接,建立活体下颌骨与混合Ⅲ型假人头结合的人体头部有限元模型。对下颌骨进行初步边界约束,模拟计算此模型以3．6m/s和10m/s速度撞击正前方刚体。结果 下颌骨以3．6m/s速度撞击正前方刚体,下颌骨会以颞下颌关节为轴向后轻微滑动,因而应力上升过程中有一回落,此处为滑动力。应力沿下颌骨外斜线向升支和颞下颌关节传递,髁突及髁突颈部应力有明显集中;下颌骨以10m/s速度撞击时,滑动力不明显,于第4～5ms时应力回弹、反射明显导致应力叠加。活体下颌骨与混合Ⅲ型假人头结合,可对下颌骨进行边界约束。在喙突(颞肌)边界约束条件下,喙突应力亦有一定改变。结论 (1)髁突及髁突颈部相对于下颌骨体其骨结构的横截面积陡然减小,骨结构的横截面积陡然减小的区域出现应力集中;(2)撞击过程中下颌骨以髁突为轴向后轻微滑动,造成此处较强的应力有集中;(3)应力回弹、反射导致应力叠加,这是下颌骨撞击损伤的生物力学机制之一。与临床下颌骨正面撞击所造成的骨折部位完全吻合。     

Activation of natural killer cell function in recreational athletes with paraplegia during a wheelchair half-marathon race

OBJECTIVE: To investigate a part of the immune homeostasis in recreational athletes with spinal cord injury (SCI) during and after a wheelchair half-marathon race. DESIGN: Case-control study in an actual race. SETTING: The half-marathon division of an international wheelchair marathon race in Japan. PARTICIPANTS: Seven male wheelchair racers with SCI between T7 and L1. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Changes in the number and function of natural killer (NK) cells and the endocrine effects, including plasma catecholamines and cortisol in blood samples obtained the day before the race, immediately after it, and 1 day after the race. RESULTS: Both the percentage and absolute number of peripheral NK cells did not change significantly throughout the experiment. Mean NK cell cytotoxic activity +/- standard deviation increased significantly, from 45.5%+/-7.5% to 56.1%+/-5.1% (P<.01) immediately after the race and remained increased until the next day. Plasma adrenaline levels were increased (P<.05) immediately after the race and recovered 1 day later; the plasma concentration of cortisol did not change throughout the experiment. CONCLUSIONS: The wheelchair half-marathon race induced activation of NK cell function in recreational athletes with SCI between T7 and L1.     

Delayed optic nerve decompression for indirect optic nerve injury

OBJECTIVE: To test the efficacy of delayed optic nerve decompression in traumatic optic nerve injury. STUDY DESIGN: Critical analysis of Proforma-based, prospectively accrued data of all cases with injury to surgery interval of greater than 2 weeks. METHODS: Thirty-five cases with a median injury to surgery interval of 56 days (range, 16-374 d). Surgical decompression was undertaken only in cases that continued to have poor vision after treatment with steroids in conventional doses (1 mg/kg prednisolone). Pre- and postoperative visual acuity measurements were converted to the logMAR scale of visual acuity and the percentage of visual improvement was calculated. RESULTS: Surgery was universally unrewarding in all 9 cases with persistent and complete blindness of greater than 2 weeks and no response to steroid therapy. Of the cases with some residual vision, 20 of 26 cases improved (mean percentage improvement, 41.0 +/- 5.7%). Cases were categorized on the basis of the injury to surgery interval into groups of 2 weeks to 2 months, 2 months to 4 months, and greater than 4 months. No significant difference was demonstrated in the probability or quantum of improvement in these groups (P =.97). CONCLUSIONS: Optic nerve decompression remains useful as a salvage procedure for conventional dose steroid failed cases of traumatic optic neuropathy. In cases that are not completely blind, vision can be improved even when surgery is undertaken a few months after the injury.     

Article 12: The prevalence of persistent postconcussive symptoms and self-reported functioning in an active duty population

Objectives: To measure (1) the prevalence of postconcussive syndrome (PCS) symptoms associated with prior traumatic brain injury (TBI) and (2) their effects on the functioning of soldiers. Design: Population survey. Setting: Army paratrooper base. Participants: Convenience sample of 2055 soldiers. Interventions: Not applicable. Main Outcome Measures: Self-reported PCS symptoms and role functioning. Results: 947 soldiers reported prior TBI, nearly all of which was mild (loss of consciousness, ≤20min), and most of which (60%) occurred within the last 5 years. Soldiers with prior mild TBI reported more moderate to severe symptoms than soldiers denying prior TBI (mean symptoms, 4.2 vs 2.1), but fewer symptoms than soldiers reporting more severe TBI (mean symptoms, 5.4). Confirmatory factor analysis replicated the clusters of symptoms previously identified in a small, clinical sample by Cicerone and Kalmar (1995). Functioning correlated weakly with symptoms (with cognitive and affective symptom clusters: r range, .09-.19; P<.001). Conclusions: Even highly functioning individuals may have sequelae from prior TBI that can affect functioning.     

Quantifying the magnitude of torque physiotherapists apply when stretching the hamstring muscles of people with spinal cord injury

OBJECTIVE: To quantify the magnitude of stretch that physiotherapists apply to the hamstring muscles of people with spinal cord injury (SCI). DESIGN: Repeated-measures design. SETTING: SCI unit in Australia. PARTICIPANTS: Fifteen individuals with motor complete paraplegia or tetraplegia. INTERVENTION: Twelve physiotherapists manually administered a stretch to the hamstring muscles of each subject. The stretch was applied by flexing the hip with the knee extended.Main Outcome Measure: Applied hip flexor torque. RESULTS: Therapists applied median hip flexor torques of between 30 and 68Nm, although some torques were as large as 121Nm. The stretch applied by different therapists to any 1 subject varied as much as 40-fold. CONCLUSION: There is a large range of stretch torques provided by physiotherapists to patients with SCI. Some therapists provide stretch torques well in excess of those tolerated by individuals with intact sensation.     

Randomized trial of 4-aminopyridine in patients with chronic incomplete spinal cord injury

Objective To test the efficacy of 4-aminopyridine (4-AP) on functional status, walking speed and vibration perception in patients with chronic, incomplete spinal cord injury. Methods Twenty SCI patients were randomized in a trial with a double-blind, crossover design to receive four weeks of orally administered 4-AP, followed by a two-week wash-out period and four weeks of placebo, or vice versa. The total daily dose of 4-AP during the four weeks of treatment was systematically increased to a maximum of 0.5 mg/kg body weight. Evaluation of (side-)effects took place at the beginning, after one week, and at the end of each four-week study period. Results No significant benefit was found on functional status (COOP-WONCA). A statistically significant treatment effect was found on the vibration perception threshold (VPT) in the left fingers, during the first study period. On average, patients receiving 4-AP treatment responded less favourably (mean increase in VPT of 0.29 (0.31) μm) than patients receiving placebo (mean decrease in VPT of 0.05 (0.35) μm) (p=0.04). Neither comfortable nor maximum walking speed altered significantly following 4-AP treatment. Conclusions No statistically significant, functional benefit from 4-AP was found for patients in the present study. Furthermore, no support was found for the possibility that an a priory selection of responsive patients would have yielded more favourable results. Received: 13 June 2000 / Received in revised form: 9 January 2001 / Accepted: 30 January 2001     

Outcome prediction in severe traumatic brain injury with transcranial Doppler ultrasonography

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Predicted impact on Victoria's ambulance services of a new major trauma system

Background: In 1999, a new major trauma system was proposed for the state of Victoria, Australia. The guidelines for the new system were aimed at delivering major trauma cases to definitive trauma care in the least time possible. The aim of the present study was to analyse the potential effect of this system on Victoria’s ambulance services. Methods: The present study modelled the workload of major trauma cases in Victoria’s ambulance service for one year pre‐ and post‐introduction of the guidelines. Cases were analysed regarding whether their first hospital destination would change under the proposed guidelines, and, subsequently, whether they would require interhospital transport to a higher level trauma service. The impact on the ambulance services was modelled as annual changes in distances travelled due to predicted changes in hospital destinations. Results: Analysis of the predicted changes indicated that, in general, Victoria"s metropolitan and rural road ambulance crews would not be greatly affected. However, some metropolitan road crews may have to travel extra distances for up to 110 cases per year. The major impact was on air retrieval crews, where the annual number of interhospital transfers is predicted to increase from approximately 150 to 330. Conclusions: The present study demonstrated that most of the impact of a new trauma system on Victoria"s ambulance services could be readily absorbed into the current workload. However, it also highlighted areas affected disproportionately within the ambulance services; in particular, air retrieval. Such studies are important to enable the effective implementation of new trauma systems.     

Epidemiology of occupational injuries and illnesses in a university population: a focus on age and gender differences

BACKGROUND: Occupational injuries and illnesses are a major preventable public health problem. METHODS: This study evaluated the incidence, nature, and cause of awarded workers' compensation claims for a large state university and teaching hospital. Rates and types of injury were compared across age and gender. RESULTS: Rates of injury varied over twofold with age, with those 16-25 having the lowest rates of injury and those 36-45 having the highest rates. Claims rates were 1.36-fold higher for women than men. Women had higher rates for injury resulting from lifting, falling, noxious exposures, repetitive motion, and carpal tunnel syndrome. Similarly women had significantly higher rates of claims for pain, sprains, bruises, burns, concussion, and inhalation injury; with lower rates of cuts, ligament injury, and jammed joints. CONCLUSIONS: These group differences suggest the need to examine age and gender job distributions and relevant ergonomic and environmental causative factors.