Dynamic Responses of Intact Post Mortem Human Surrogates from Inferior-to-Superior Loading at the Pelvis

During certain events such as underbody blasts due to improvised explosive devices, occupants in military vehicles are exposed to inferior-to-superior loading from the pelvis. Injuries to the pelvis-sacrum-lumbar spine complex have been reported from these events. The mechanism of load transmission and potential variables defining the migration of injuries between pelvis and or spinal structures are not defined. This study applied inferior-to-superior impacts to the tuberosities of the ischium of supine-positioned five post mortem human subjects (PMHS) using different acceleration profiles, defined using shape, magnitude and duration parameters. Seventeen tests were conducted. Overlay temporal plots were presented for normalized (impulse momentum approach) forces and accelerations of the sacrum and spine. Scatter plots showing injury and non-injury data as a function of peak normalized forces, pulse characteristics, impulse and power, loading rate and sacrum and spine accelerations were evaluated as potential metrics related to pathological outcomes with the focus of examining the role of the pulse characteristics from inferior-to-superior loading of the pelvis-sacrum-lumbar spine complex. Interrelationships were explored between non-fracture and fracture outcomes, and fracture patterns with a focus on migration of injuries from the hip-only to hip and spine to spine-only regions. Observations indicate that injury to the pelvis and or spine from inferior-to-superior loading is associated with pulse and not just peak velocity. The role of the effect of mass recruitment and injury migration parallel knee-thigh-hip complex studies, suggest a wider application of the recruitment concept and the role of the pulse characteristics.

Evaluation of clinical efficacy and safety of cervical trauma collars: differences in immobilization, effect on jugular venous pressure and patient comfort

BACKGROUND

Concern has been raised that cervical collars may increase intracranial pressure in traumatic brain injury. The purpose of this study was to compare four types of cervical collars regarding efficacy of immobilizing the neck, effect on jugular venous pressure (JVP), as a surrogate for possible effect on intracranial pressure, and patient comfort in healthy volunteers.

METHODS

The characteristics of four widely used cervical collars (Laerdal Stifneck(®) (SN), Vista(®) (VI), Miami J Advanced(®) (MJ), Philadelphia(®) (PH)) were studied in ten volunteers. Neck movement was measured with goniometry, JVP was measured directly through an endovascular catheter and participants graded the collars according to comfort on a scale 1-5.

RESULTS

The mean age of participants was 27 ± 5 yr and BMI 26 ± 5. The mean neck movement (53 ± 9°) decreased significantly with all the collars (p < 0.001) from 18 ± 7° to 25 ± 9° (SN < MJ < PH < VI). There was a significant increase in mean JVP (9.4 ± 1.4 mmHg) with three of the collars, but not with SN, from 10.5 ± 2.1 mmHg to 16.3 ± 3.3 mmHg (SN < MJ < VI < PH). The grade of comfort between collars varied from 4.2 ± 0.8 to 2.2 ± 0.8 (VI > MJ > SN > PH).

CONCLUSION

Stifneck and Miami J collars offered the most efficient immobilization of the neck with the least effect on JVP. Vista and Miami J were the most comfortable ones. The methodology used in this study may offer a new approach to evaluate clinical efficacy and safety of neck collars and aid their continued development.

[Calculation of the strain-deformation condition of the spinal motor segment during loading]

A mathematical model is proposed to analyze the spinal strain-deformation condition resulting from axial and lateral g-loads generated by changes in the gravity field and/or pilot's maneuvering high-performance aircraft. The solution algorithm takes into account changes in the intervertebral disk pressure and the fibrous ring shape at the time of close-to-critical g values. Calculation of the spinal strain-deformation condition was implemented by the instrumentality of computer system SPLEN (KOMMEK ltd., Russia). Analysis of the spinal strain-deformation condition was made for 2 types of external loads, i.e. normal and unilateral with a bending moment. Maximum permissible loads on a spinal segment were evaluated, as well as distribution of strain intensity, mean strains, spinal deformation and destruction field was described. The constructed computer models could be used as a basis for developing a technique of predicting characteristic spinal injuries in consequence of specific extreme loads and pathologies.

[Rehabilitative treatment of patients with complicated spinal injuries and trophic disorders in specialized neurological center]

The analysis of treatment results 132 patients with consequences with spine injury and the presence of venous disorders which in conditions of specialized health resort management system applied in complex restorative treatment, which includes patogeneti no-reasonable comprehensive preparation, surgery and further restorative treatment. Based on the analysis and systematization of the results developed diagnostic and therapeutic algorithm and algorithm for planning surgical tactics.

Motion in the unstable cervical spine when transferring a patient positioned prone to a spine board

CONTEXT

Two methods have been proposed to transfer an individual in the prone position to a spine board. Researchers do not know which method provides the best immobilization.

OBJECTIVE

To determine if motion produced in the unstable cervical spine differs between 2 prone logrolling techniques and to evaluate the effect of equipment on the motion produced during prone logrolling.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Tests were performed on 5 fresh cadavers (3 men, 2 women; age = 83 ± 8 years, mass = 61.2 ± 14.1 kg).

MAIN OUTCOME MEASURE(S)

Three-dimensional motions were recorded during 2 prone logroll protocols (pull, push) in cadavers with an unstable cervical spine. Three equipment conditions were evaluated: football shoulder pads and helmet, rigid cervical collar, and no equipment. The mean range of motion was calculated for each test condition.

RESULTS

The pull technique produced 16% more motion than the push technique in the lateral-bending angulation direction (F1,4 = 19.922, P = .01, η(2) = 0.833). Whereas the collar-only condition and, to a lesser extent, the football-shoulder-pads-and-helmet condition demonstrated trends toward providing more stability than the no-equipment condition, we found no differences among equipment conditions. We noted an interaction between technique and equipment, with the pull maneuver performed without equipment producing more anteroposterior motion than the push maneuver in any of the equipment conditions.

CONCLUSIONS

We saw a slight difference in the motion measured during the 2 prone logrolling techniques tested, with less lateral-bending and anteroposterior motion produced with the logroll push than the pull technique. Therefore, we recommend adopting the push technique as the preferred spine-boarding maneuver when a patient is found in the prone position. Researchers should continue to seek improved methods for performing prone spine-board transfers to further decrease the motion produced in the unstable spine.

[Clinical features and strategies for the treatment of cervical spinal injury in aged patients]

OBJECTIVE

To investigate clinical features and treatments of cervical spinal injury in aged patients.

METHODS

From July 2006 to October 2011, 27 patients with cervical spinal cord injury were divided into experiment group, including 20 males and 7 females with an average age of 69 years old (ranged 65 to 78 years old). The other 22 patients with the same degree of cervical spianl cord injury and the same period hospitalization were chosen to regard as control group, including 16 males and 6 females with an average age of 47 years old (ranged 38 to 65 years old). All of them had clear history of trauma, and were admitted to hospital within one week. Clinical data and result of follow up were evaluated between two group. The function of the spinal cord was measured by Frankel classification at admission and final follow-up.

RESULTS

All patients were followed up for 1 year except 6 died in aged group, among which 3 paients with complications were died during hospitalization and others were out of hospital. Twenty-three cases had accompanied diseases and 24 cases occurred complications in aged group. Contrast to control group, this difference was statistically significant. At the final follow-up, there were 2 cases at Frankel grade E in aged group and 6 cases in control group.

CONCLUSION

In comparison with control group, there are more accompany diseases and higher complications and mortality rates in aged group, while poor improvement of spinal cord function. This patients were mainly treated with operation, but operation method should simplify and mainly focus on effective decompression and reconstuction stability and avoid expansion operation. It's nesscerry to pay more attention to prevent and treatment of respiratory complication.

[Algorithm of diagnostics and surgery of trauma and degenerative diseases of cervical spine]

A retrospective analysis of diagnostics and surgery in 240 patients was made. The vertebral spinal trauma took place in 168 patients (average age 31 +/- 5 years), degenerative dystrophic diseases of spine were in 72 patients (average age 52 +/- 7 years). The clinicodiagnostic complex included survey and functional radiography of the spine, magnetic resonance image and helical computer tomography of the spine with spondylometric measurements and color duplex scanning of the vertebral artery. Stabilization of the spine was performed in 137 (57%) cases. The variants were determined on the basis of predominate injury of 1 out of 3 supporting complexes. The rigid and dynamic methods and their combination were used for fixation of the spine. More favorable results were registered using dynamic fixation and the arthroplasty of intervertebral disks with nitinol constructions. An algorithm of radiodiagnostics and surgery methods were proposed.

[Cardiac pathology and autonomic dysfunction in patients with vertebral and spinal cord injury]

The disturbances of cardiovascular function were examined in 103 patients with vertebral and spinal cord injury. To evaluate myocardial conduction time and regulation of heart rate we used the method of spiroarteriocardiorythmography. Comparative power spectral and time domain analyses of heart rate variability were carried out in patient and healthy individuals. The autonomic nervous system dysfunction revealed in patients result in severe cardiovascular complications and is associated with high risk of heart diseases.

[The features of cardio-respiratory system and autonomic regulation in parasportsmen with spinal injury]

A comprehensive study of the functional state of basketball athletes in wheelchairs with spinal cord injuries in the T6-T10 and paraplegia (n = 9, mean age 26.6 +/- 1.7 years) was held. As a control, we used disability groups with a similar injury, leading an active life (n = 13, mean age 44.5 +/- 2.6 years), athletes ( = 14, mean age 24.6 +/- 1.3 years) and healthy physically active men (n = 15, the average age of 24.9 +/- 0.6 years). In the athletes in wheelchairs it was revealed an increase in the length of the body in a sitting position, the increase in tidal volume and increasing in the effectiveness of the functional respiratory tests. These changes in the state of the musculoskeletal system and autonomic systems to ensure physical activity classified as adaptive and due to sports training. In the state of the cardiovascular system and its autonomic regulation parasportsmen showed a reduction in trauma-induced increase in diastolic blood pressure and increase in the magnitude of arterial baroreflex sensitivity, decreased due to spinal injury. These data indicate availability of compensatory processes aimed at optimizing the cardiovascular system through the mechanisms of baroreflex regulation.

Mechanical failure begins preferentially near resorption cavities in human vertebral cancellous bone under compression

The amount of bone turnover in the body has been implicated as a factor that can influence fracture risk and bone strength. Here we test the idea that remodeling cavities promote local tissue failure by determining if microscopic tissue damage (microdamage) caused by controlled loading in vitro is more likely to form near resorption cavities. Specimens of human vertebral cancellous bone (L4, 7 male and 2 female, age 70±10, mean±SD) were loaded in compression to the yield point, stained for microscopic tissue damage and submitted to three-dimensional fluorescent imaging using serial milling (image voxel size 0.7×0.7×5.0 μm). We found the resulting damage volume per bone volume (DV/BV) was correlated with percent eroded surface (p<0.01, r(2)=0.65), demonstrating that whole specimen measures of resorption cavities and microdamage are related. Locations of microdamage were more than two times as likely to have a neighboring resorption cavity than randomly selected sites without microdamage (relative risk 2.39, 95% confidence interval of relative risk: 2.09-2.73), indicating a spatial association between resorption cavities and microdamage at the local level. Individual microdamage sites were 48,700 (40,100; 62,700) μm(3) in size (median, 25th and 75th percentiles). That microdamage was associated with resorption cavities when measured at the whole specimen level as well as at the local level provides strong evidence that resorption cavities play a role in mechanical failure processes of cancellous bone and therefore have the potential to influence resistance to clinical fracture.

Total motion generated in the unstable thoracolumbar spine during management of the typical trauma patient: a comparison of methods in a cadaver model

OBJECT

The proper prehospital and inpatient management of patients with unstable spinal injuries is critical for prevention of secondary neurological compromise. The authors sought to analyze the amount of motion generated in the unstable thoracolumbar spine during various maneuvers and transfers that a trauma patient would typically be subjected to prior to definitive fixation.

METHODS

Five fresh cadavers with surgically created unstable L-1 burst fractures were tested. The amount of angular motion between the T-12 and L-2 vertebral segments was measured using a 3D electromagnetic motion analysis device. A complete sequence of maneuvers and transfers was then performed that a patient would be expected to go through from the time of injury until surgical fixation. These maneuvers and transfers included spine board placement and removal, bed transfers, lateral therapy, and turning the patient prone onto the operating table. During each of these, the authors performed what they believed to be the most commonly used versus the best techniques for preventing undesirable motion at the injury level.

RESULTS

When placing a spine board there was more motion in all 3 planes with the log-roll technique, and this difference reached statistical significance for axial rotation (p = 0.018) and lateral bending (p = 0.003). Using logrolling for spine board removal resulted in increased motion again, and this was statistically significant for flexion-extension (p = 0.014). During the bed transfer and lateral therapy, the log-roll technique resulted in more motion in all 3 planes (p ≤ 0.05). When turning the cadavers prone for surgery there was statistically more angular motion in each plane for manually turning the patient versus the Jackson table turn (p ≤ 0.01). The total motion was decreased by almost 50% in each plane when using an alternative to the log-roll techniques during the complete sequence (p ≤ 0.007).

CONCLUSIONS

Although it is unknown how much motion in the unstable spine is necessary to cause secondary neurological injury, the accepted tenet is to minimize motion as much as possible. This study has demonstrated the angular motion incurred by the unstable thoracolumbar spine as experienced by the typical trauma patient from the field to positioning in the operating room using the best and most commonly used techniques. As previously reported, using the log-roll technique consistently results in unwanted motion at the injured spinal segment.

A biomechanical assessment of floor and overhead lifts using one or two caregivers for patient transfers

This study investigated the differences in peak external hand forces and external moments generated at the L5/S1 joint of the low back due to maneuvering loaded floor-based and overhead-mounted patient lifting devices using one and two caregivers. Hand forces and external moments at the L5/S1 joint were estimated from ground reaction forces and motion capture data. Caregivers gave ratings of perceived exertion as well as their opinions regarding overhead vs. floor lifts. Use of overhead lifts resulted in significantly lower back loads than floor lifts. Two caregivers working together with a floor lift did not reduce loads on the primary caregiver compared to the single-caregiver case. In contrast, two-caregiver operation of an overhead lift did result in reduced loads compared to the single-caregiver case. Therefore, overhead lifts should be used whenever possible to reduce the risk of back injury to caregivers. The use of two caregivers does not compensate for the poorer performance of floor lifts.

[Spinal injury: multidetector computed tomography features and mechanism]

As one of the severe injuries, spinal injury is common in major blunt trauma and a spinal cord injury can make the patient be disabled or life-threatened with poor long-term physical and psychological consequences. The treatment of spinal injuries is a significant proportion of all the workload of trauma management based on the neurologic defect, spinal column instability, and the compression of spinal cord. Multidetector computed tomography (MDCT) is the better examination than conventional radiography in depicting the type of injuries, spinal column instability, spinal canal narrowing degree and neurologic defect, and can be performed alone in patients sustaining severe trauma. The purpose of this review is to evaluate the MDCT features of this types of injuries based on the mechanism.

A cable-driven locomotor training system for restoration of gait in human SCI

A novel cable-driven robotic locomotor training system was developed to provide compliant assistance/resistance forces to the legs during treadmill training in patients with incomplete spinal cord injury (SCI). Eleven subjects with incomplete SCI were recruited to participate in two experiments to test the feasibility of the robotic gait training system. Specifically, 10 subjects participated in one experimental session to test the characteristics of the robotic gait training system and one subject participated in repeated testing sessions over 8 weeks with the robotic device to test improvements in locomotor function. Limb kinematics were recorded in one experiment to evaluate the system characteristics of the cable-driven locomotor trainer and the overground gait speed and 6 min walking distance were evaluated at pre, 4 and 8 weeks post treadmill training of a single subject as well. The results indicated that the cable driven robotic gait training system improved the kinematic performance of the leg during treadmill walking and had no significant impact on the variability of lower leg trajectory, suggesting a high backdrivability of the cable system. In addition, results from a patient with incomplete SCI indicated that prolonged robotic gait training using the cable robot improved overground gait speed. Results from this study suggested that a cable driven robotic gait training system is effective in improving leg kinematic performance, yet allows variability of gait kinematics. Thus, it seems feasible to improve the locomotor function in human SCI using this cable driven robotic system, warranting testing with a larger group of patients.

Evaluation of dynamic formation of cervical spine column based on functional radiological studies in patients after cervical spine injury

The purpose of this study was to evaluate cervical spine function, based on our own functional method of roentgenometric analysis in patients who suffered from cervical spine sprain injury. Study involved 72 patients who suffered from cervical spine whiplash injury. Conventional plain radiographs in all patients included three lateral views: maximum flexion, neutral (resting) and maximum extension. All views allowed roentgenometric evaluation of ligament instability of the lower cervical spine C5-C7 according to the White and Panjabi criteria. Furthermore, based on literature analysis and their own clinical observations, the authors proposed new classification of dynamic formation of cervical spine column. The dynamic formation of cervical column is evaluated based on pathomechanical chain of being between normal and unstable. Authors' own evaluation system in flexion views can be useful in diagnosis and treatment of this type of injury.

Influence of whiplash injury on cervical spine stability

The aim of this study was to define the influence of whiplash injury on cervical spine stability. The study involved 72 patients who had suffered from sprain injury to cervical spine of 0⁰-III⁰ according to QTF. To verify the results the authors examined the control group whose representatives have never suffered from any cervical spine injury and met all the exclusion criteria. Conventional plain radiographs in both groups showed three lateral views: maximum flexion, neutral (resting) position and maximum extension view. The results of image studies were subjected to roentgenometric analysis to find mechanical symptoms of instability according to radiological criteria: AADI, anterior translation and regional angulation. The authors demonstrated that there was no influence of whiplash injury on mechanical stability of cervical spine measured on radiograms in static-functional lateral views.

[Accident analysis and biomechanics: relevance of technical reports for the medical assessment of spinal injuries]

The number of claims linked to whiplash injuries is steadily increasing in most European countries. After minor accidents the question often arises as to whether the occupant could really have been injured. The technical expert may calculate the biomechanical stress imposed on the occupants by the impact from the evidence gathered after the accident. Based on this data the medical expert is able to judge whether this stress was sufficient to produce the injury claimed. The threshold of biomechanical loading necessary for spinal injuries will be deduced from a technical perspective. With the help of examples, the steps required to preserve evidence will be explained.

Kinematic response of the spine during simulated aircraft ejections

INTRODUCTION

Military aviators are susceptible to spinal injuries during high-speed ejection scenarios. These injuries commonly arise as a result of strains induced by extreme flexion or compression of the spinal column. This study characterizes the vertebral motion of two postmortem human surrogates (PMHS) during a simulated catapult phase of ejection on a horizontal decelerator sled.

METHODS

During testing, the PMHS were restrained supinely to a mock ejection seat and subjected to a horizontal deceleration profile directed along the local z-axis. Two midsized males (175.3 cm, 77.1 kg; 185.4 cm, 72.6 kg) were tested. High-rate motion capture equipment was used to measure the three-dimensional displacement of the head, vertebrae, and pelvis during the ejection event.

RESULTS

The two PMHS showed generally similar kinematic motion. Head injury criterion (HIC) results were well below injury threshold levels for both specimens. The specimens both showed compression of the spine, with a reduction in length of 23.9 mm and 45.7 mm. Post-test autopsies revealed fractures in the C5, T1, and L1 vertebrae.

DISCUSSION

This paper provides an analysis of spinal motion during an aircraft ejection.The injuries observed in the test subjects were consistent with those seen in epidemiological studies. Future studies should examine the effects of gender, muscle tensing, out-of-position (of head from neutral position) occupants, and external forces (e.g., windblast) on spinal kinematics during aircraft ejection.

High cycle fatigue behaviour of functional spinal units

Vibrations have been shown to be an important risk factor for spinal pathologies. The underlying mechanisms are poorly understood and in vivo data scarce and difficult to obtain. Consequently numerical models are used to estimate spinal loading; requiring fatigue strength information, which was obtained in this study for spinal specimens from young and old male donors of working age in vitro. Bone mineral density (BMD) and endplate area were determined using CT scans. Three groups were investigated: young specimens in neutral posture, young in flexed posture, and old in neutral posture. The loading consisted of 300,000 sinusoidal compression cycles of 2 kN, inducing a nucleus pressure peek of approximately 1.4 MPa. No failure of the young specimens in neutral posture was observed, but four specimens from older donors with low BMD failed. The product between endplate area and BMD was shown to be useful to predict fatigue strength for old donors and should therefore be considered with regard to whole body vibration injuries. In flexed posture, two specimens from young donors failed. One failure can be attributed to low BMD following the trend for the old specimens; the other failure could not be explained, leaving the influence of flexion yet unclear.

Rehabilitation of the spine following sports injury

The spine plays an essential role in the contribution toward athletic performance. As the central pillar of the body, the structures of the spine are susceptible to injury related with sports participation. This article identifies many of the most commonly seen sports-related injuries to the spine, and discusses practical rehabilitative interventions to manage such injuries. Anatomic considerations, biomechanical movements, and tissue properties are explained to better understand the clinical expectations associated with each of the injuries described.

Rear seat occupant safety: an investigation of a progressive force-limiting, pretensioning 3-point belt system using adult PMHS in frontal sled tests

Rear seat adult occupant protection is receiving increased attention from the automotive safety community. Recent anthropomorphic test device (ATD) studies have suggested that it may be possible to improve kinematics and reduce injuries to rear seat occupants in frontal collisions by incorporating shoulder-belt force-limiting and pretensioning (FL+PT) technologies into rear seat 3-point belt restraints. This study seeks to further investigate the feasibility and potential kinematic benefits of a FL+PT rear seat, 3-point belt restraint system in a series of 48 kmh frontal impact sled tests (20 g, 80 ms sled acceleration pulse) performed with post mortem human surrogates (PMHS). Three PMHS were tested with a 3-point belt restraint with a progressive (two-stage) force limiting and pretensioing retractor in a sled buck representing the rear seat occupant environment of a 2004 mid-sized sedan. Instrumentation included belt tension load cells, accelerometers on the head and at multiple locations on the spine, and chestbands to measure the chest deformation contours in the transverse plane. The kinematics of the subjects were quantified using off-board, high-speed video. The results of these tests were then compared to matched PMHS tests, published in 2008, performed in the same environment with a standard (not-force limited, not pretensioning) 3-point belt restraint. The FL+PT restraint system resulted in significant (p<0.05) decreases in peak shoulder belt tension (average +/- standard deviation: 4.4 +/- 0.13 kN with the FL+PT belt, 7.8 +/- 0. 6 kN with the standard belt) and 3 ms-resultant, mid-spine acceleration (FL+PT: 34 +/- 3.8 g; standard belt: 44 +/- 1.4 g). The FL+PT tests also produced more forward torso rotation caused by decreased forward excursion of the pelvis and increased payout out of the shoulder belt by the force-limiter. These results support the previous ATD studies that suggest that it may be possible to improve the kinematics of rear seat occupants in this type of collision using a 3-point belt system with a shoulder belt retractor equipped with a two-stage force-limiter and pretensioner.

Airway management for cervical spine injury

In this review, important factors related to initial management, diagnosis, airway, and anesthetic management of patients with cervical spine injury (CSI) are discussed. Early diagnostic and clinical evaluation is important in excluding CSI. In-line stabilization reduces movement of the cervical spine. Tracheal intubation under fiberscopic control, offers safety, and comfort to the patient. However, in cases of severe deterioration of vital functions, intubation must be performed without any delay at the site of the accident or in the emergency room. Early airway management and maintenance of spinal immobilization are more important factors in limiting the risk of secondary neurological injury than any particular technique. The current opinion is that oral intubation after intravenous induction of anesthesia and muscle relaxation along with in-line stabilization is the safest and quickest way to achieve intubation in a patient with suspected CSI.