Road crash casualties: characteristics of police injury severity misclassification

BACKGROUND: In most countries, epidemiologic knowledge of road crash injury is mainly based on police data, as they very often are the only available data at the nation-wide level. However their validity is of some concern. We focus here on the police severity classification of 'serious' and 'slight' casualties in France. We want to know how the police classification compares with a trauma severity scale, so that we could correctly interpret police based studies. METHOD: The study is based on the Rh?ne county (population 1.6 million) during the 1997 to 2001 period. Police data have been linked with a road trauma registry, so that both police and New Injury Severity Score (NISS) classifications are available on 14,342 casualties. The police classification of 'slight' and 'serious' casualties is compared with the registry classification grouped into NISS 1-15 and NISS 16-75 categories. We conduct multivariate analyses of the probability of police severity misclassification, over and under-classification, as a function of crash and casualty characteristics. RESULTS: Kappa is estimated at 0.41; the sensitivity of the police classification is 72% and the positive predictive value is 35%. Pedestrian and motorcyclist casualties are the most likely to be over-classified (Relative Risk [RR] = 1.4 and RR = 1.2, respectively compared with car occupants). The 'rural police' are more likely to over-classify than the other police forces (RR = 3.1). Over-classification decreased during the 1997 to 2001 period whereas under- classification increased. CONCLUSION: These misclassification characteristics must be kept in mind when interpreting severity results based on police data. We are working on obtaining unbiased nation-wide estimates of severity figures.     

Update on design and biomechanics of cervical disc arthroplasty

Anterior cervical discectomy and fusion (ACDF) has been considered the mainstay of care for cervical spondylosis despite its association with decreased spinal mobility, altered kinematics, and risk of adjacent segment disease. Cervical disc arthroplasty (CDA) has recently emerged as a potential alternative that allows for preservation of motion and restoration of physiologic load distribution at both the index and adjacent levels. The growing interest and strong clinical evidence supporting the use of CDA has led to several changes in implant design. This review aims to discuss the implementation of CDA as an alternative to ACDF as well as provide an update on advancements in implant design and their influence of spinal biomechanics.     

The structure, physiology, and biomechanics of articular cartilage: injury and repair

Hyaline cartilage which surrounds the articular surfaces and allows for painless movement of synovial joints by reducing friction is composed of chondrocytes embedded within an extracellular matrix made up of a macromolecular framework and water. Due to its avascular, aneural, and hypocellular structure, its response to trauma is very restricted. The main components of the extracellular matrix are water, proteoglycans, collagen, and other proteins and glycoproteins. Homeostasis of the hyaline cartilage is maintained mainly by chondrocytes. Collagen provides the tensile and shearing properties of the cartilage and immobilizes the proteoglycans within the matrix. The mechanical behavior of the cartilage depends on the interactions between collagen, proteoglycans, and interstitial fluid components. The mechanical strength of the hyaline cartilage is determined by the permeability of the solid matrix, flow of the interstitial fluid in the tissue, and the balance between the solid and fluid phases. Injuries that only disrupt the hyaline cartilage do not have a healing potential; but those involving the subchondral bone as well as articular cartilage cause fibrin clot formation, release of growth factors, and increase in cell activities like migration, proliferation, differentiation, and matrix synthesis.     

The biomechanics of a thumb carpometacarpal immobilization splint: design and fitting.

Splinting for the common osteoarthritis of the carpometacarpal (CMC) joint of the thumb is infrequently described in the literature, but the few splints that are described include one or both adjacent joints. This paper describes the design and biomechanics of a custom-molded thumb CMC immobilization splint that excludes the thumb metacarpophalangeal and wrist joints. The problem of the imbalance of extrinsic extensor/abductor forces against the intrinsic flexor/adductor forces is described. The accompanying weakening of the thumb CMC capsule allows dorsal shifting of the proximal end of the metacarpal, producing pain. The splint described in this paper 1) prevents motion of the first metacarpal in relation to the other metacarpals, 2) prevents tilting (flexion) of the first metacarpal during pinch, and 3) allows unrestricted thumb metacarpal and wrist joint motion. Attention to detail during construction is required for an accurate pattern, precise positioning of the CMC joint during molding, accurate molding around the first metacarpal, and well-distributed pressure. This design may also be used for protection following thumb CMC arthroplasty or thumb CMC sprain or strain and as a base for thumb metacarpophalangeal and/or interphalangeal mobilization splinting.     

Experimental trauma to the malar eminence: fracture biomechanics and injury patterns.

OBJECTIVES: To document patterns of facial fractures after trauma to the malar eminence and to elucidate biomechanical factors relevant to the injury patterns. STUDY DESIGN AND SETTING: Studies were conducted on 14 cadaver heads. Study variables included impact velocity, contact area, impact force, and zygomatic skin thickness. Bony fractures and clinical injury patterns were documented. A fracture severity rating scale was devised and statistically correlated to the study variables using regression ANOVA analysis. RESULTS: A broad spectrum of facial fracture patterns was found. Skin thickness and surface area did not correlate with fracture severity (P = 0.67, P = 0.83, respectively). Impact force demonstrated a trend toward significance (P = 0.14). Velocity was most correlative with fracture severity (P = 0.07). A critical threshold velocity (3.5 m/s) was found to correlate with the most severe fracture patterns. CONCLUSIONS: A broad spectrum of facial fracture patterns was demonstrated after experimental trauma to the malar eminence. Contact surface area and zygomatic skin thickness were not found to be significant factors in fracture severity. Velocity, rather than impact force, was most correlative with fracture severity. The most severe fracture patterns were elicited by velocities above 3.5 m/s.     

Incidence and crash mechanisms of aortic injury during the past decade

BACKGROUND: Aortic injuries were traditionally thought to be the result of severe frontal crashes. Newer data has suggested other crash types such as nearside crashes may also be important in aortic injury. We hypothesized the implementation of recent safety measures would decrease the incidence of aortic injury associated with fatal motor vehicle crashes. METHODS: The autopsy reports of all traffic fatalities for motor vehicle occupants in a large urban county for the years 1993 to 2004 were examined. The demographics, impact types, safety measures used, and the presence of any aortic injury were recorded. Trends were evaluated for significance by weighted linear regression. RESULTS: The incidence of aortic injury associated with fatal motor vehicle crashes has remained unchanged during the past 12 years (r = 0.057, p = 0.45). There is a trend toward decreased aortic injuries associated with frontal crashes (r = 0.26, p = 0.089) but no change in aortic injuries associated with nearside or farside crashes (r = 0.053, p = 0.47), when the crash resulted in a fatality. This is despite an increase in seat belt use and increased presence of airbags during the same time period. CONCLUSIONS: Despite improved safety measures designed to minimize the occurrence of aortic injuries, the incidence of blunt aortic injury in fatal motor vehicle crashes has not decreased during the past decade. Although not statistically significant, there is a trend toward decreased frontal impacts in fatal motor vehicle crashes associated with aortic injuries. The nearside crash mechanism continues to play a prominent role, and efforts at improving vehicle safety should be focused on crash mechanisms as they relate to aortic injury.     

The current injury situation of bicyclists--a medical and technical crash analysis

BACKGROUND: The purpose of the study was to analyze the actual injury situation of bicyclists in Germany to create a basis for effective preventive measures. METHODS: Technical and medical data were prospectively collected shortly after the crash at the crash scenes. RESULTS: Included were 4,264 injured bicyclists from 1985 to 2003. Fifty-five percent of the bicyclists were male and 45% were women. The mean age of bicyclists was 52.0 years. The crashes took place in urban areas in 95.2% of the cases, and in rural areas in 4.8% of the cases. Collision opponents were cars in 65.8%, trucks in 7.2%, bicyclists in 7.4%, standing objects in 8.8%, multiple opponents or objects in 4.3%, and others in 6.5%. The mean collision speed was 21.3 km/h. The helmet use rate was 1.7%. Fifty-five percent of bicyclists used bicycle traffic lanes before the crash. The mean Maximum Abbreviated Injury Scale/Injury Severity Score (ISS) was 1.45 of 3.9. The incidence of multiple injuries (ISS>16)/death was 2.0%/1.5%. The ISS/Maximum Abbreviated Injury Scale score was higher in bicyclists without a helmet than in bicyclists with a helmet, and in bicyclists who had not used bicycle traffic lanes than in bicyclists who had used bicycle traffic lanes (t test, p<0.05). CONCLUSION: In bicyclists, head and extremities are at high risk for injuries. The helmet use rate is unsatisfactorily low. Remarkably, two-thirds of the head injuries could have been prevented by helmets. More consequent helmet use and an extension of bicycle traffic lanes for a better separation of bicyclists and motorized vehicles would be simple but very effective preventive measures.     

锂剂促进周围神经损伤修复的初步研究

目的 探讨锂剂对周围神经损伤后神经再生的影响.方法 取48只雌性SD大鼠,制作大鼠右侧坐骨神经损伤动物模型,通过腹腔注射氯化锂,在不同时间点观察动物下肢活动情况,检测小腿三头肌神经电生理及肌湿重,并对损伤远端神经纤维的神经丝蛋白(NF200)、单核巨噬细胞抗原(ED1)、P-75和运动终板进行免疫组织化学染色观察.结果 损伤后4周,实验组动物下肢已接近正常行走步态,对照组右侧肢体仍明显跛行;损伤后2周和4周,实验组的复合肌肉动作电位(CMAP)波幅较对照组明显增大,两组间的差异有统计学意义(P＜0.05);损伤后4周、8周,实验组的小腿三头肌重量较对照组明显增大,两组间差异有统计学意义(P＜0.05);损伤后3 d,在距离损伤远端5 mm处,实验组坐骨神经纤维内NF200呈连续丝状染色,而对照组仍然是颗粒状染色;损伤后4周,在神经肌肉接头处,可观察到实验组肌肉运动终板有新生神经纤维支配,而对照组运动终板上无神经纤维支配,两组ED1及P75染色未见明显差别.结论 锂剂可有效促进周围神经损伤后的再生,但其机制仍需进一步研究.     

The role of biomechanics and inflammation in cartilage injury and repair

Osteoarthritis is a painful and debilitating disease characterized by progressive degenerative changes in the articular cartilage and other joint tissues. Biomechanical factors play a critical role in the initiation and progression of this disease, as evidenced by clinical and animal studies of alterations in the mechanical environment of the joint caused by trauma, joint instability, disuse, or obesity. The onset of these changes after joint injury generally has been termed posttraumatic arthritis and can be accelerated by factors such as a displaced articular fracture. Within this context, there is considerable evidence that interactions between biomechanical factors and proinflammatory mediators are involved in the progression of cartilage degeneration in posttraumatic arthritis. In vivo studies have shown increased concentrations of inflammatory cytokines and mediators in the joint in mechanically induced models of osteoarthritis. In vitro explant studies confirm that mechanical load is a potent regulator of matrix metabolism, cell viability, and the production of proinflammatory mediators such as nitric oxide and prostaglandin E2. Knowledge of the interaction of inflammatory and biomechanical factors in regulating cartilage metabolism would be beneficial to an understanding of the etiopathogenesis of posttraumatic osteoarthritis and in the improvement of therapies for joint injury.     

锂剂促进周围神经损伤修复的初步研究

目的 探讨锂剂对周围神经损伤后神经再生的影响.方法 取48只雌性SD大鼠,制作大鼠右侧坐骨神经损伤动物模型,通过腹腔注射氯化锂,在不同时间点观察动物下肢活动情况,检测小腿三头肌神经电生理及肌湿重,并对损伤远端神经纤维的神经丝蛋白(NF200)、单核巨噬细胞抗原(ED1)、P-75和运动终板进行免疫组织化学染色观察.结果 损伤后4周,实验组动物下肢已接近正常行走步态,对照组右侧肢体仍明显跛行;损伤后2周和4周,实验组的复合肌肉动作电位(CMAP)波幅较对照组明显增大,两组间的差异有统计学意义(P＜0.05);损伤后4周、8周,实验组的小腿三头肌重量较对照组明显增大,两组间差异有统计学意义(P＜0.05);损伤后3 d,在距离损伤远端5 mm处,实验组坐骨神经纤维内NF200呈连续丝状染色,而对照组仍然是颗粒状染色;损伤后4周,在神经肌肉接头处,可观察到实验组肌肉运动终板有新生神经纤维支配,而对照组运动终板上无神经纤维支配,两组ED1及P75染色未见明显差别.结论 锂剂可有效促进周围神经损伤后的再生,但其机制仍需进一步研究.

Abstract：

Objective To evaluate the effect of lithium on nerve regeneration after peripheral nerve injury.Methods Sciatic nerve crash injury model was created on the right side of 48 female SD rats.Lithium was administered after the injury by intraperitoneal injection.Locomotion of the lower limbs, electromyography and wet muscle weight of the triceps muscles were measured at different time points after the injury.Changes of NF200, ED1, P-75 and motor end plate at the distal part of the injured nerve were detected by immunohistostaining.Results Four weeks after sciatic nerve crash injury, animals that received lithium injection restored near normal gait, whereas the control animals were limping.Two and four weeks after the injury, the lithium injection group had significantly higher CMAP amplitude than the control group.Four and eight weeks after the injury, the wet muscle weight in lithium injection group was significantly heavier than the control group.Three days after crush injury, continuous NF200 positive fibers were found 5 mm distal to the injury site in the lithium injection group, whereas in the control group, only granular NF200 positive staining was observed Four weeks after crush injury, new innervations to the motor end plate were detected in the neuromuscular junction in the lithium injection group, but not in the control group.No differences in ED1 and P75 staining were detected.Conclusion Lithium could significantly promote axon regeneration after peripheral nerve crush injury.Its mechanism is subject to further investigation.     

锂剂促进周围神经损伤修复的初步研究

目的 探讨锂剂对周围神经损伤后神经再生的影响.方法 取48只雌性SD大鼠,制作大鼠右侧坐骨神经损伤动物模型,通过腹腔注射氯化锂,在不同时间点观察动物下肢活动情况,检测小腿三头肌神经电生理及肌湿重,并对损伤远端神经纤维的神经丝蛋白(NF200)、单核巨噬细胞抗原(ED1)、P-75和运动终板进行免疫组织化学染色观察.结果 损伤后4周,实验组动物下肢已接近正常行走步态,对照组右侧肢体仍明显跛行;损伤后2周和4周,实验组的复合肌肉动作电位(CMAP)波幅较对照组明显增大,两组间的差异有统计学意义(P＜0.05);损伤后4周、8周,实验组的小腿三头肌重量较对照组明显增大,两组间差异有统计学意义(P＜0.05);损伤后3 d,在距离损伤远端5 mm处,实验组坐骨神经纤维内NF200呈连续丝状染色,而对照组仍然是颗粒状染色;损伤后4周,在神经肌肉接头处,可观察到实验组肌肉运动终板有新生神经纤维支配,而对照组运动终板上无神经纤维支配,两组ED1及P75染色未见明显差别.结论 锂剂可有效促进周围神经损伤后的再生,但其机制仍需进一步研究.     

Chronic allograft injury: Mechanisms and potential treatment targets

Improving long-term graft survival remains one of the critical challenges facing kidney transplantation since a great portion of kidney grafts are lost by 10 years after transplantation. Understanding the causes of chronic allograft injury and providing timely therapeutic interventions are essential for improving these outcomes. In this review, we will discuss the recent data that emerged turning down calcineurin inhibitors as the primary cause of long-term graft injury and highlighting the increased importance of non-compliance, antibody-mediated injury, disease recurrence, and BK nephropathy as culprits. We suggest a number of different strategies to better manage kidney transplant recipients that, ultimately, may improve long-term graft survival.     

Pelvic ring fractures: implications of vehicle design, crash type, and occupant characteristics

BACKGROUND: Pelvic ring fractures (PRFs) are a major cause of morbidity and mortality in motor vehicle collisions (MVCs). Understanding the factors leading to PRFs may help improve vehicle design and safety. This study sought to determine the vehicular, crash, and occupant characteristics that contribute to PRFs. METHODS: From 1997 to 2003, 240 adult patients involved in lateral or frontal crashes were prospectively studied. Comprehensive crash reconstructions, vehicle analysis, and occupant data were compiled and analyzed as part of the national Crash Injury Research Engineering Network project. RESULTS: Of 240 study patients, 38 had PRFs. The incidence of PRFs was significantly associated with female gender, lateral impact crashes, vehicle incompatibility, and severity of crash. Seat belts and airbags were not protective against PRFs in either lateral or frontal crashes. CONCLUSIONS: All vehicles in the current study were less than 6 years old at the time of the MVC and thus reflect newer safety designs. Compared with studies of PRFs in MVCs before the widespread adoption of modern safety standards, our series suggests there has been a modest decrease in the incidence of PRFs in newer vehicles. Current safety standards do not adequately protect against PRFs, especially in lateral MVCs involving incompatibility and female occupants. New technology needs to be developed and implemented. Our data suggest that side impact airbags, alteration of vehicle geometry, and increased reinforcement of side panels and doors may result in fewer PRFs.     

Mechanisms of myocardial reperfusion injury

Reperfusion of the ischemic myocardium results in irreversible tissue injury and cell necrosis, leading to decreased cardiac performance. While early reperfusion of the heart is essential in preventing further tissue damage due to ischemia, reintroduction of blood flow can expedite the death of vulnerable, but still viable, myocardial tissue, by initiating a series of events involving both intracellular and extracellular mechanisms. In the last decade, extensive efforts have focused on the role of cytotoxic reactive oxygen species, complement activation, neutrophil adhesion, and the interactions between complement and neutrophils during myocardial reperfusion injury. Without reperfusion, myocardial cell death evolves slowly over the course of hours. In contrast, reperfusion after an ischemic insult of sufficient duration initiates an inflammatory response, beginning with complement activation, followed by the recruitment and accumulation of neutrophils into the reperfused myocardium. Modulation of the inflammatory response, therefore, constitutes a potential pharmacological target to protect the heart from reperfusion injury. Recognition of the initiating factor(s) involved in myocardial reperfusion injury should aid in development of pharmacological interventions to selectively or collectively attenuate the sequence of events that mediate extension of tissue injury beyond that caused by the ischemic insult.     

Mechanisms of homocysteine-induced glomerular injury and sclerosis

Hyperhomocysteinemia (hHcys) has been recognized as a critical risk or pathogenic factor in the progression of end-stage renal disease (ESRD) and in the development of cardiovascular complications related to ESRD. Recently, evidence is accumulating that hHcys may directly act on glomerular cells to induce glomerular dysfunction and consequent glomerular sclerosis, leading to ESRD. In this review, we summarize recent findings that reveal the contribution of homocysteine as a pathogenic factor to the development of glomerular sclerosis or ESRD. In addition, we discuss several important mechanisms mediating the pathogenic action of homocysteine in the glomeruli or in the kidney, such as local oxidative stress, endoplasmic reticulum stress, homocysteinylation, and hypomethylation. Understanding these mechanisms may help design new approaches to develop therapeutic strategies for treatment of hHcys-associated end-organ damage and for prevention of deterioration of kidney function and ultimate ESRD in patients with hypertension and diabetes mellitus or even in aged people with hHcys.