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Study Design: This was a retrospective case series at a single institution., Objective: The study was performed to investigate the characteristics of spinal injuries in survivors of suicidal jumping., Summary of Background Data: Spinal fracture/dislocation is associated with high-energy trauma such as that induced by motor vehicle accidents. Survivors of suicidal jumping sometimes sustain spinal injuries. However, the characteristics of such spinal injuries are unclear., Methods: We identified 87 survivors of suicidal jumping who sustained spinal injuries from 2007 to 2016 in our institution. We compared the demographic data, radiological findings, neurological status, associated injuries, treatments, and mental health conditions between these 87 survivors and 204 non-suicidal patients with spinal injury., Results: Suicidal jumpers were predominantly female (67%) and 10 years younger than non-suicidal patients. Mental health problems, mainly schizophrenia and depression, were diagnosed in 77% of suicidal jumpers. Neurological damage from spinal trauma was generally less severe in suicidal jumpers than in non-suicidal patients. Most spinal injuries in suicidal jumpers were located in the thoracic or lumbar spine region (85%). Among comorbid injuries, extremity injuries were highly associated with spine injury in suicidal jumpers. Nearly 70% of suicidal jumpers exhibited extremity injury in contrast to 33% of non-suicidal patients. Approximately, 25% of suicidal jumpers underwent surgical treatment. Surgical treatment was similarly performed on suicidal jumpers and non-suicidal patients regardless of the discrepancy in neurological damage between these two groups., Conclusion: Spinal injuries in suicidal jumpers differed from spinal injuries in non-suicidal patients with regard to sex, age, mental health condition, injury location, neurologic damage, and associated injuries. Most survivors of suicidal jumping were young female patients with mental health problems. They tended to have thoracic and lumbar spine trauma rather than cervical trauma with less severe neurological deficits and a higher incidence of accompanying limb injury., Level of Evidence: 3.

Study Design: Retrospective cohort study., Objective: To identify patient characteristics and associated injuries in those sustaining a spine fracture from personal watercraft (PWC) usage., Summary of Background Data: There are few studies regarding PWC use and injuries, and even more scarce are studies evaluating PWC usage and spine injuries. Identifying high-risk actions and individuals can help to effectively treat them, reduce mortality, and possibly avoid certain spine fractures., Methods: Retrospective analysis of 142 patients admitted from the emergency department with PWC-related injuries at a single-level I trauma center from January 1, 2004 to May 1, 2017. Twenty-six (18.3%) sustained a spine fracture, totaling 71 fractures. Statistical analysis was used to investigate the patient characteristics, specific mechanisms of injury, injury severity score (ISS), and associated injuries. Patients expiring (12) had incomplete evaluations and were excluded from most reported results., Results: Spine fractures were not associated with age, race, or sex, but were associated with a higher ISS, intensive care unit length, in-patient length of stay, cerebral injury, and abdominal/genitourinary (GU) injury. There were 8 cervical fractures, 22 thoracic fractures, 33 lumbar, and 8 sacral fractures. Axial load injuries were associated with vertebral body fractures and specifically burst fractures. Being a driver or passenger did not influence likelihood of a spine fracture, but did correlate with abdominal/GU injury. Five (19.2%) of patients with spine fractures required eight spine surgeries during admission. Mortality was associated with females, severe systemic injuries (ISS ≥ 15), direct collision mechanism of injury, and the spring season., Conclusion: PWC usage may result in spine fractures with a moderate percentage requiring orthopedic surgery. Additional studies should examine how hull or seat modifications can lessen the risk of axial loads leading to spine fractures. PWC patients with spine fractures should also be evaluated for abdominal/GU and cerebral injuries at presentation., Level of Evidence: 4.

Study Design: Adult patients who received computed tomography (CT) alone or CT-magnetic resonance imaging (MRI) for the evaluation of cervical spine injury., Objective: To evaluate the utility of CT-MRI in the diagnosis of cervical spine injury using propensity-matched techniques., Summary of Background Data: The optimal evaluation (CT alone vs. CT and MRI) for patients with suspected cervical spine injury in the setting of blunt trauma remains controversial., Methods: The primary outcome was the identification of a cervical spine injury, with decision for surgery and change in management considered secondarily. A propensity score was developed based on the likelihood of receiving evaluation with CT-MRI, and this score was used to balance the cohorts and develop two groups of patients around whom there was a degree of clinical equipoise in terms of the imaging protocol. Logistic regression was used to evaluate for significant differences in injury detection in patients evaluated with CT alone as compared to those receiving CT-MRI., Results: Between 2007 and 2014, 8060 patients were evaluated using CT and 693 with CT-MRI. Following propensity-score matching, each cohort contained 668 patients. There were no significant differences between the two groups in baseline characteristics. The odds of identifying a cervical spine injury were significantly higher in the CT-MRI group, even after adjusting for prior injury recognition on CT (odds ratios 2.6; 95% confidence interval 1.7-4.0; P < 0.001). However, only 53/668 patients (8%) in the CT-MRI group had injuries identified on MRI not previously recognized by CT. Only a minority of these patients (n = 5/668, 1%) necessitated surgical intervention., Conclusion: In this propensity-matched cohort, the addition of MRI to CT alone identified missed injuries at a rate of 8%. Only a minority of these were serious enough to warrant surgery. This speaks against the standard addition of MRI to CT-alone protocols in cervical spine evaluation after trauma., Level of Evidence: 3.

Study Design: A retrospective epidemiological study., Objective: To reveal incidence and epidemiological features of traumatic spinal injuries (TSI) in Northern Finland., Summary of Background Data: In Finland the annual incidence of traumatic spine fractures requiring inpatient care has been found to be 27/100,000, while international incidences have varied across the range of 16-64/100,000. More specific epidemiological data from Finland is not available. Internationally, the most common mechanisms of injury are road traffic as well as low and high falls. Associated injuries occur in 30% to 55% of cases., Methods: The study sample included patients with traumatic spinal injury admitted to Oulu University Hospital (OYS) with injury between the January 1, 2007 and December 31, 2011. Patient information was collected from the hospital care register, including all inpatient and outpatient visits and surgical procedures. Traumatic spinal column and spinal cord injuries were identified using International Classification of Diseases 10th revision or Nordic Classification of Surgical Procedures codes and all patient records were manually reviewed., Results: Nine hundred seventy-one patients met the criteria for TSI. The mean annual incidence of hospitalized traumatic spinal injuries was 26/100,000 in the whole of Northern Finland and 35/100,000 in the OYS main responsibility area. The most frequent etiology of TSI was low falls, which accounted for 35.8% of the injuries, followed by road traffic and high falls. Lumbar spine was the most common site of the fracture. Spinal surgery was performed in 376 (38.7%) cases. Three hundred eight patients (31.7%) suffered from associated injuries, 101 (10.4%) had a spinal cord injury, and 71 (7.3%) a brain injury., Conclusion: Low falls in elderly and road traffic injuries in younger age groups were the most common etiology of traumatic spinal injuries in Northern Finland and should be given more attention in primary prevention., Level of Evidence: 3.

Study Design: In vitro animal cadaveric study., Objective: To identify the appropriate rotational speed and safe bone distance from neural tissue during bone burring in spinal surgery., Summary of Background Data: Bone burring is a common step in spinal surgery. Unwanted frictional heat produced during bone burring may result in thermal injury to the bone and adjacent neural structure. One of the important parameters influencing the bone temperature rise during bone burring is rotational speed., Methods: This laboratory-based animal study used bovine spine bones, and the tests were conducted using a steel round burr. The bone temperature was measured simultaneously with thermocouple at the distances of 1 mm, 3 mm, and 5 mm from the burring site during the burring process. The bone burring was done with 4 different rotational speeds of 35,000 revolutions per minute (rpm), 45,000 rpm, 65,000 rpm, and 75,000 rpm., Results: This study showed that increasing the rotational speed significantly elevated bone temperature. The threshold temperature of 47°C was reached when bone was burred for 10 seconds, with a rotational speed of 45,000 rpm. The mean bone temperature measured at a distance 1 mm from the burring site for all 4 rotational speeds was always higher than that measured at a distance of 3 mm and 5 mm and this difference was statistically significant (P < 0.001). There was no significant difference between the mean bone temperature measured at a distance of 3 mm and 5 mm (P > 0.05)., Conclusion: Taking 47°C as the threshold temperature for causing significant impairment to the regenerative capacity of bone, a rotational speed of lower than 45,000 rpm is preferable so as to minimize thermal injury to bone tissue. We also concluded that a 3-mm distance between the site of burring and the neural tissue is a safe distance., Level of Evidence: N/A.

Study Design: Retrospective analysis of a prospective data set., Objective: Determine the incidence and epidemiology of combat-related spinal injuries for the wars in Afghanistan and Iraq., Summary of Background Data: Recent studies have identified a marked increase in the rate of combat-related spine trauma among casualties in Afghanistan and Iraq. Limitations in these previous works, however, limit their capacity for generalization., Methods: A manual search of casualty records stored in the Department of Defense Trauma Registry was performed for the years 2005 to 2009. Demographic information, nature of spinal wounding, injury mechanism, concomitant injuries, year, and location of injury were recorded for all soldiers identified as having sustained combat-related spine trauma. Incidence rates were constructed by comparing the frequencies of spine casualties against defense manpower deployment data. Multivariate Poisson regression was used to identify statistically significant factors associated with spinal injury., Results: In the years 2005 to 2009, 872 (11.1%) casualties with spine injuries were identified among a total of 7877 combat wounded. The mean age of spine casualties was 26.6 years. Spine fractures were the most common injury morphology, comprising 83% of all spinal wounds. The incidence of combat-related spinal trauma was 4.4 per 10,000, whereas that of spine fractures was 4.0 per 10,000. Spinal cord injuries occurred at a rate of 4.0 per 100,000. Spinal cord injuries were most likely to occur in Afghanistan (incident rate ratio: 1.96; 95% confidence interval: 1.68-2.28), among Army personnel (incident rate ratio: 16.85; 95% confidence interval: 8.39-33.84), and in the year 2007 (incident rate ratio: 1.90; 95% confidence interval: 1.55-2.32). Spinal injuries from gunshot were significantly more likely to occur in Iraq (17%) than in Afghanistan (10%, P = 0.02)., Conclusion: The incidence of spine trauma in modern warfare exceeds reported rates from earlier conflicts. The study design and population size may enhance the capacity for generalization of our findings., Level of Evidence: 3.

Study Design: Pain behavior and immunohistological analysis in intervertebral disc (IVD) injury model., Objective: To investigate pain behavior in a rat model of IVD injury using the CatWalk system., Summary of Background Data: There are few reports examining low back pain behavior in animal models. The CatWalk is a computer-assisted gait analysis system that provides an automated way to assess gait function and pain-related alterations of this behavior., Methods: In the IVD injury group, L5-L6 IVDs were injured with a 24-gauge needle. Simultaneously, the neurotracer Fluoro-Gold (FG; Fluorochrome, Denver, CO) was injected into the L5-L6 IVDs. In the sham group, FG was injected into the L5-L6 IVDs only. Animals in the control group received no operation. One, 2, 3, and 4 weeks after surgery, the gait of rats in the 3 groups was investigated using the CatWalk system. One, 2, and 4 weeks after surgery, in IVD injury and sham groups, dorsal root ganglions from the L1 to L6 levels were resected. Dorsal root ganglions were immunostained for calcitonin gene-related peptide., Results: In the IVD injury group, the mean stands of hind paws and the mean duty cycle of front paws at some time points were significantly higher than those in the sham group. Furthermore, the mean stride length of the front and hind paws and the mean swing speed of the front and hind paws at some time points were significantly shorter than those in the sham group. The proportion of calcitonin gene-related peptide-immunoreactive, FG-labeled neurons among all FG-labeled dorsal root ganglion neurons in the IVD injury group was significantly higher than the corresponding proportion in the sham group., Conclusion: These results suggest that IVD injury produced significant changes in rat gait, including longer stance phases and shorter strides. In the future, we may be able to apply the CatWalk system to the evaluation of behavior associated with pain in models of low back pain., Level of Evidence: N/A.

Study Design: Survival analyses of a large cohort of published lumbar spine compression fatigue tests., Objective: To produce the first large-scale evaluation of human lumbar spine tolerance to repetitive compressive loading and to evaluate and improve guidelines for human exposure to whole-body vibration and repeated mechanical shock environments., Summary of Background Data: Several studies have examined the effects of compressive cyclic loading on the lumbar spine. However, no previous effort has coalesced these studies and produced an injury risk analysis with an expanded sample size. Guidelines have been developed for exposure limits to repetitive loading (e.g., ISO 2631-5), but there has been no large-scale verification of the standard against experimental data., Methods: Survival analyses were performed using the results of 77 male and 28 female cadaveric spinal segment fatigue tests from 6 previously published studies. Segments were fixed at each end and exposed to axial cyclic compression. The effects of the number of cycles, load amplitude, sex, and age were examined through the use of survival analyses., Results: Number of cycles, load amplitude, sex, and age all are significant factors in the likelihood of bony failure in the spinal column. Using a modification of the risk prediction parameter from ISO 2631-5, an injury risk model was developed, which relates risk of vertebral failure to repeated compressive loading. The model predicts lifetime risks less than 7% for industrial machinery exposure from axial compression alone. There was a 38% risk for a high-speed planing craft operator, consistent with epidemiological evidence., Conclusion: A spinal fatigue model which predicts the risk of in vitro lumbar spinal failure within a narrow confidence interval has been developed. Age and sex were found to have significant effects on fatigue strength, with sex differences extending beyond those accounted for by endplate area disparities.

Study Design: An in vitro biomechanics investigation exposing porcine functional spinal units (FSUs) to submaximal cyclic or static compressive forces while in a flexed, neutral, or extended posture., Objective: To investigate the combined effect of cyclically applied compressive force (e.g., vibration) and postural deviation on intervertebral joint mechanics., Summary of Background Data: Independently, prolonged vibration exposure and non-neutral postures are known risk factors for development of low back pain and injury. However, there is limited basic scientific evidence to explain how the risk of low back injury from vibration exposure is modified by other mechanical factors. This work examined the influence of static postural deviation on vertebral joint height loss and compressive stiffness under cyclically applied compressive force., Methods: Forty-eight FSUs, consisting of 2 adjacent vertebrae, ligaments, and the intervening intervertebral disc were included in the study. Each specimen was randomized to 1 of 3 experimental posture conditions (neutral, flexed, or extended) and assigned to 1 of 2 loading protocols, consisting of (1) cyclic (1500 ± 1200 N applied at 5 Hz using a sinusoidal waveform, resulting in 0.2 g rms acceleration) or (2) 1500 N of static compressive force. RESULTS.: As expected, FSU height loss followed a typical first-order response in both the static and cyclic loading protocols, with the majority (~50%) of the loss occurring in the first 20 minutes of testing. A significant interaction between posture and loading protocol (P < 0.001) was noted in the magnitude of FSU height loss. Subsequent analysis of simple effects revealed significant differences between cyclic and static loading protocols in both a neutral (P = 0.016) and a flexed posture (P < 0.0001). No significant differences (P = 0.320) were noted between pre/postmeasurements of FSU compressive stiffness., Conclusion: Posture is an important mechanical factor to consider when assessing the risk of injury from cyclic loading to the lumbar spine.

Study Design: Case report and literature review., Objective: To report the case of a young patient who sustained a penetrating wound with a knife tip retained in his cervical vertebrae and to review the literature., Summary of Background Data: Stab wound with foreign body retained, associated with spinal cord injury and vertebral artery injury, is not commonly reported. The timing and approach of surgical intervention are still controversial., Methods: A 17-year-old boy with a wound in the neck presented with diminishing feeling and dysfunction of the left leg and arm. Radiographs demonstrated a foreign body at the C4 level, and possible spinal cord and vertebral artery injuries were detected by computed tomography. Digital subtracted angiography showed a small lateral opening of the injured artery, which was successfully embolized. The knife tip was removed from the original wound without severe cerebrospinal fluid leakage or bleeding,, Results: The patient achieved immediate improvement after the operation., Conclusion: Cases of simultaneous spinal cord injury and vertebral artery injury in which the foreign body is retained are uncommonly reported. Digital subtracted angiography is necessary for cervical penetrating wounds and surgical approach should be individualized.

Study Design: Prospective cohort study., Objective: To study whether there is a sequential pattern in the posterior ligamentous complex (PLC) rupture caused by deforming traumatic forces by analyzing magnetic resonance (MR) images in a consecutive prospective cohort of patients with traumatic vertebral fracture., Summary of Background Data: PLC plays an important role in vertebral stability. However, the sequence in which the different components of the PLC tear, in the face of traumatic forces, has not been yet described., Methods: Prospective study of 74 consecutive vertebral acute traumatic fractures analyzed using radiography and magnetic resonance imaging (MRI) (FS-T2-w/short-tau inversion-recovery [STIR] sequences). Fracture morphology was classified according to the AO classification. Integrity of each PLC component-facet capsules, interspinous ligament (ISL), supraspinous ligament (SSL), and ligamentum flavum (LF)-was assessed and classified as intact, edema, or disruption. ISL edema was further subdivided depending on the extension (>50%/<50%). We analyzed the association between MRI signal and the AO progressive scale of morphological damage., Results: AO type A1/A2 fractures associated with only facet distraction. A3 fractures showed additional ISL edema, usually less than 50%, with neither SSL nor LF disruption. Type B1 fractures associated with facet distraction, ISL edema or disruption, and low rate of SSL/LF disruptions; B2 fractures increased SS/LF disruption rates. Type C fractures associated with facet fracture or dislocation and ISL, SSL, or LF complete rupture. We found high association (P < 0.001) between AO progressive scale and MRI signal. MRI analysis showed that posterior distraction forces begin in the facets and extend throughout the ISL, starting at its posterosuperior margin (finally disinserting the SSL superiorly) and traveling diagonally toward anteroinferior border, finally tearing the LF., Conclusion: MR images correlated with AO progressive scale of morphological damage, which showed a progressive orderly rupture sequence among the different PLC components as traumatic forces increased.

Study Design: Case report., Objective: To describe a sudden spinal cord injury in a girl with Prader-Willi syndrome (PWS) 1 week after posterior T2-L3 fusion., Summary of Background Data: PWS is a genetic disorder characterized by several features including growth deficiency, hypotonia, obesity, and spinal deformities. In PWS patients the prevalence of scoliosis and of kyphosis is reported to be 15% to 86% and 8% to 40%, respectively. Operative treatment carries specific and serious risks in these patients., Methods: A 13-year-old girl with PWS underwent a ventral release and a posterior spinal fusion for a scoliosis with hyperkyphosis of the thoracic spine. Preoperatively, she had no osteopenia or obesity. Posterior instrumentation consisted of fixation with pedicle screws, proximally assisted by a bilateral transverse hook to prevent junctional hyperkyphosis., Results: Postoperative recovery was initially uneventful; however, 1 week after operation the patient suddenly suffered a complete spinal cord lesion at level T4. This was due to myelum compression with a spinal dislocation cranial to the fusion level, and subsequent proximal hook failure. The patient underwent immediate removal of the transverse hooks, an extension of the fusion to T1, and a laminectomy at T2. Eighteen months after the event she was still paraplegic., Conclusion: This report describes a sudden and complete spinal cord lesion 1 week after spinal fusion in a child with PWS. Although such an event is often attributed to osteopenia, this was not proven in this case. To our knowledge, this is the first report to describe this event developing so soon and so suddenly after primary surgery. This case report confirms that spinal surgery in patients with PWS carries an increased risk of junctional hyperkyphosis and pullout of hardware.

Study Design: Review of whiplash injury mechanisms and effects of anti-whiplash systems including active head restraint (AHR) and Whiplash Protection System (WHIPS)., Objective: This article provides an overview of previous biomechanical and epidemiological studies of AHR and WHIPS and investigates whether seat design and biomechanical knowledge of proposed whiplash injury mechanisms translates to understanding outcomes of rear crash occupants., Summary of Background Data: In attempt to reduce whiplash injuries, some newer automobiles incorporate anti-whiplash systems such as AHR or WHIPS. During a rear crash, mechanically based systems activate by occupant momentum pressing into the seatback whereas electronically based systems activate using crash sensors and an electronic control unit linked to the head restraint., Methods: To investigate the effects of AHR and WHIPS on occupant responses including head and neck loads and motions, biomechanical studies of simulated rear crashes have been performed using human volunteers, mathematical models, crash dummies, whole cadavers, and hybrid cadaveric/surrogate models. Epidemiological studies have evaluated the effects of AHR and WHIPS on reducing whiplash injury claims and lessening subjective complaints of neck pain after rear crashes. RESULTS.: Biomechanical studies indicate that AHR and WHIPS reduced the potential for some whiplash injuries but did not completely eliminate the injury risk. Epidemiological outcomes indicate reduced whiplash injury claims or subjective complaints of crash-related neck pain between 43 and 75% due to AHR and between 21% and 49% due to WHIPS as compared to conventional seats and head restraints., Conclusion: Yielding energy-absorbing seats aim to reduce occupant loads and accelerations whereas AHRs aim to provide early head support to minimize head and neck motions. Continued objective biomechanical and epidemiological studies of anti-whiplash systems together with industry, governmental, and clinical initiatives will ultimately lead to reduced whiplash injuries through improved prevention strategies.

Study Design: Narrative review., Objective: To summarize the evidence that implicates the cervical zygapophysial joints as the leading source of chronic neck pain after whiplash., Summary of Background Data: Reputedly a patho-anatomic basis for neck pain after whiplash has been elusive. However, studies conducted in a variety of disparate disciplines indicate that this is not necessarily the case., Methods: Data were retrieved from studies that addressed the postmortem features and biomechanics of injury to the cervical zygapophysial joints, and from clinical studies of the diagnosis and treatment of zygapophysial joint pain, to illustrate convergent validity., Results: Postmortem studies show that a spectrum of injuries can befall the zygapophysial joints in motor vehicle accidents. Biomechanics studies of normal volunteers and of cadavers reveal the mechanisms by which such injuries can be sustained. Studies in cadavers and in laboratory animals have produced these injuries.Clinical studies have shown that zygapophysial joint pain is very common among patients with chronic neck pain after whiplash, and that this pain can be successfully eliminated by radiofrequency neurotomy., Conclusion: The fact that multiple lines of evidence, using independent techniques, consistently implicate the cervical zygapophysial joints as a site of injury and source of pain, strongly implicates injury to these joints as a common basis for chronic neck pain after whiplash.

Study Design: Retrospective radiographic and clinical review of patients in a comprehensive trauma database., Objective: The primary aim of this study was to detect occipitocervical complex (OCC) injuries initially missed at a level 1 trauma center., Summary of Background Data: Recent case series demonstrate that OCC injuries are potentially survivable. Delay in diagnosis can lead to increased morbidity and mortality., Methods: Normative maximum values that included 97.5% of the population were defined, with a sample of 251 consecutive normal computed tomographic (CT) scans for the Basion-Dens Interval (BDI), atlantooccipital interval, and lateral mass interval (LMI) of C1-C2. Subsequently, 844 cervical CT scans from consecutive polytrauma patients were reviewed for the evidence of OCC injury. Measurements greater than the normative maximum values were considered suspicious for injury. A BDI greater than 12 mm or a BDI greater than 10 mm with a confirmatory magnetic resonance imaging was considered a definite evidence of an OCC injury, as was an LMI 4 mm or greater with confirmatory magnetic resonance imaging. The electronic medical record was reviewed to determine whether an injury was detected on any final neuroradiology report or during follow-up. RESULTS.: Five patients had evidence of atlantooccipital dissociation (AOD), and two had atlantoaxial dissociation (AAD). Of these, three cases of AOD and two cases of AAD were missed on the final report by the neuroradiologist. The undiagnosed patients were subsequently diagnosed by orthopedic surgeons consulted for axial spine or other musculoskeletal trauma. No patients who were diagnosed with AAD or AOD in the electronic medical record were missed by using the criteria of BDI greater than 10 mm and LMI 4 mm or greater to define OCC injuries., Conclusion: OCC injuries can be missed even with standardized multidetector CT with multiplanar reconstructions. High-quality normative data used to determine a reliable picture archiving and communication system-based measurement of the OCC anatomy can detect ligamentous injuries initially missed in polytrauma patients.

Study Design: Case cohort., Objective: To illuminate factors associated with all-terrain vehicle (ATV) injuries and injury morphology., Summary of Background Data: Traditionally thought of as safe, injuries associated with ATVs can be severe and life threatening. In 2005 alone, the US Consumer Product Safety Commission estimated 136,100 injuries and 767 deaths associated with ATVs use and misuse., Methods: A database of all spine related consults from one institution was reviewed and all patients with spine or spinal cord injuries associated with ATV use were identified. All pertinent demographic, clinical, and radiographic information were collected and analyzed., Results: Thirty-six patients were identified from the spinal cord injury database. The male:female ratio was 11:1 of the ATV injured patient. This is statistically different from the general database population, with a males representing 70% of patients (P < 0.002). The average ATV injured patient was 13.7 years younger than the average database patient (P < 0.001). The incidence of an axial compression or burst type fracture morphology was significantly higher in the ATV injured patient population (50%) compared with the database population as a whole (12%). Factors predisposing patients to injury on ATVs include excessive speed, use of alcohol or controlled substances, use of machinery after dark, and inexperience., Conclusion: All-terrain vehicles (ATVs) are currently experiencing enormous popularity in the United States. These recreational vehicles are associated with a higher incidence of axial compression and burst-type fracture morphologies. In general, all-terrain vehicles although highly dangerous leading to death or serious injury can be fun, enjoyable, and safe if proper regulations and safety precautions are implemented and followed.

Study Design: Retrospective case review., Objective: This study aims to characterize a broad spectrum of spinal injuries, from minor soft tissue injuries to spinal cord injuries. We hypothesized that the pattern of pediatric spinal injury would depend on age and cause., Summary of Background Data: While pediatric spinal trauma is generally considered to be rare, the impact of serious spinal trauma is considerable, both in medical and socioeconomic terms. Comparison of serious and minor injuries has rarely been carried out for pediatric spinal injury cases., Methods: All children up to age 16 who sustained spinal trauma, as defined by ICD10 codes, at 2 pediatric trauma hospitals in Sydney, Australia were identified (N = 340). Data on injury mechanism (defined as the causative event), type, and spinal level were collected and analyzed using logistic regression., Results: Traffic-related incidents accounted for approximately one third of all spinal trauma and half of serious injuries. The cervical spine was the most frequently injured region, with thoracic and lumbar spine injuries becoming more common with age. The upper cervical spine was more commonly seriously injured in young children, and the lower cervical spine was involved more often in older children. The frequency of minor soft tissue neck injuries increased substantially above the age of 8. Serious spinal injury is more likely to occur in conjunction with multiple trauma. Road traffic incidents were more likely to result in serious spinal injury than falls or sporting incidents., Conclusion: This study has shown that the pattern of spinal injury in children is related to age and also the mechanism of injury. While traffic-related incidents are a leading cause of injury across all age groups, emphasis on fall prevention is needed for younger children. Older children, particularly boys, are sustaining spinal trauma in sporting and recreational activities.

Study Design: An in vitro biomechanical study using aged human and adolescent porcine discs., Objectives: To find the leakage pathway and effect of needle gauge on the degree of disc injury post anular puncture., Summary of Background Data: Spinal needles are widely used for minimal invasive disc surgeries and disc degeneration/regeneration research. Applications of anular puncture require different diameters of spinal needles. However, the effect of needle diameters on the disc injury has not been systematically studied yet., Methods: Four groups of experiments were conducted: 1) porcine thoracic disc, 2) human thoracic disc, 3) porcine thoracic disc with 200 N external loading, and 4) porcine lumbar discs. The disc was punctured consecutively with needles from smaller diameter to larger diameter. After each anular puncture, the quantitative discomanometry technique was conducted to quantify the disc rupture pressure and volume. The association between needle gauge and rupture pressure and volume was analyzed., Results: The degree of disc injury increased with the diameter of needle. For an aged human thoracic disc, the anulus fibrosus cannot hold pressure more than 2 MPa after a 21-gauge-needle-anular-puncture. The leakage pathway of injected saline was through the anular fissure but was through the endplate when the disc was next to an osteoporotic vertebrae. The pressure holding power of porcine disc is stronger than of human disc. The rupture pressure of porcine lumbar disc is higher than of porcine thoracic disc. The axial compressive external loading increased the disc rupture pressure. The rupture volumes were not affected by the dimension of injury fissure. The rupture volume was at level of 0.3 mL without external loading and at 0.2 mL with external loading., Conclusion: A spinal needle of < or = 22 gauge and injection volume of < or = 0.2 mL are recommended to prevent postsurgery leakage.

Study Design: A prospective case-series study., Objective: To evaluate the results of nonoperative and operative treatment of symptomatic unilateral lumbar pars stress injuries or spondylolysis., Summary of Background Data: Most patients become asymptomatic following nonoperative treatment for unilateral lumbar pars stress injuries or spondylolysis. Surgery, however, is indicated when symptoms persist beyond a reasonable time affecting the quality of life in young patients, particularly the athletic population., Methods: We treated 42 patients (31 male, 11 female) with unilateral lumbar pars stress injuries or spondylolysis. Thirty-two patients were actively involved in sports at various levels. Patients with a positive stress reaction on single photon emission computerized tomography imaging underwent a strict protocol of activity restriction, bracing, and physical therapy for 6 months. At the end of 6 months, patients who remained symptomatic underwent a computed tomography (CT) scan to confirm the persistence of a spondylolysis. Eight patients subsequently underwent a direct repair of the defect using the modified Buck's Technique. Baseline Oswestry Disability Index (ODI) and Short-Form-36 (SF-36) scores were compared with 2-year ODI and SF-36 scores for all patients., Results: Eight of nine fast bowlers in cricket were right-handed. The spondylolytic defect appeared on the left side of their lumbar spine. In the nonoperated group, the mean pretreatment ODI was 36 (SD = 10.5), improving to 6.2 (SD = 8.2) at 2 years. In SF-36 scores, the mean score for physical component of health (PCS) improved from 30.7 (SD = 3.2) to 53.5 (SD = 6.5) (P < 0.001), and the mean score for the mental component of health (MCS) improved from 39 (SD = 4.1) and 56.5 (SD = 3.9) (P < 0.001) at 2 years. Twenty of 32 patients resumed their sporting career within 6 months of onset of treatment, and a further 4 of 32 patients returned to sports within 1 year. The 8 patients who remained symptomatic at 6 months underwent a unilateral modified Buck's repair. The most common level of repair was L5 (n = 5). One patient with spina bifida and a right-sided L5 pars defect remained symptomatic following direct repair. The mean preoperative ODI was 39.4 (SD = 3.6), improving to 6.4 (SD = 5.2) at the latest follow-up. The mean score of PCS (SF-36) improved from 29.6 (SD = 4.4) to 49.2 (SD = 6.2) (P < 0.001), and the mean score of MCS (SF-36) improved from 38.7 (SD = 1.9) to 54.5 (SD = 6.4) (P < 0.001)., Conclusions: The increased incidence of the unilateral lumbar pars stress injuries or frank defect on the contralateral side in a throwing sports, e.g., cricket (fast bowling), may be related to the hand dominance of the individual. Nonoperative treatment for patients with a unilateral lumbar pars stress injuries or spondylolysis resulted in a high rate of success, with 81% (34/42) of patients avoiding surgery. If symptoms persist beyond a reasonable period, i.e., 6 months, and reverse gantry CT scan confirms a nonhealing defect of the pars interarticularis, one may consider a unilateral direct repair of the defect with good functional outcome. Direct repair in patients with spina bifida at the same lumbar level as the unilateral defect may be complicated by nonunion.

Study Design: Head-turned whole cervical spine model was stabilized with muscle force replication and subjected to simulated rear impacts of increasing severity. Multiplanar flexibility testing evaluated any resulting injury., Objectives: To identify and quantify cervical spine soft tissue injury and injury threshold acceleration for head-turned rear impact, and to compare these data with previously published head-forward rear and frontal impact results., Summary of Background Data: Epidemiologically and clinically, head-turned rear impact is associated with increased injury severity and symptom duration, as compared to forward facing. To our knowledge, no biomechanical data exist to explain this finding., Methods: Six human cervical spine specimens (C0-T1) with head-turned and muscle force replication were rear impacted at 3.5, 5, 6.5, and 8 g, and flexibility tests were performed before and after each impact. Soft tissue injury was defined as a significant increase (P < 0.05) in intervertebral flexibility above baseline. Injury threshold was the lowest T1 horizontal peak acceleration that caused the injury., Results: The injury threshold acceleration was 5 g with injury occurring in extension or axial rotation at C3-C4 through C7-T1, excluding C6-C7. Following 8 g, 3-plane injury occurred in extension and axial rotation at C5-C6, while 2-plane injury occurred at C7-T1., Conclusions: Head-turned rear impact caused significantly greater injury at C0-C1 and C5-C6, as compared to head-forward rear and frontal impacts, and resulted in multiplanar injuries at C5-C6 and C7-T1.

Study Design: Whole cervical spine model with muscle force replication was subjected to simulated frontal impacts of increasing severity, and resulting injuries were evaluated via flexibility testing., Objectives: To identify and quantify cervical spine soft tissue injury and the injury threshold acceleration due to frontal impact., Summary of Background Data: Cervical spine instability may result from automotive collisions. No previous studies have quantified soft tissue injuries due to frontal impact., Methods: Six human cervical specimens (occiput-T1) with muscle force replication were subjected to frontal impacts of 4, 6, 8, and 10 g. Before frontal impact, baseline flexibility data were collected following a 2 g simulation. Flexibility parameters of total (flexion plus extension) neutral zone (NZ), flexion NZ, total range of motion (ROM), and flexion ROM were obtained following each impact and compared with baseline flexibility. Injury was a significant increase (P < 0.05) in intervertebral flexibility due to frontal impact over baseline. Injury threshold was the lowest T1 peak acceleration that caused injury., Results: The injury threshold acceleration was 8 g, as determined by significant increases of 12.6 to 51.4% over the baseline flexibility, in the C4-C5 total NZ, and the C6-C7 total NZ, flexion NZ, total ROM, and flexion ROM. Following 10 g, significant increases in flexibility parameters were observed at C2-C3, C3-C4, C4-C5, C6-C7, and C7-T1., Conclusions: Middle (C2-C3 to C4-C5) and lower (C6-C7 and C7-T1) cervical spine were at risk for injury during frontal impacts, for the experimental conditions studied.

Study Design: In vitro acceleration study on human cadaveric cervical spine specimens., Objectives: To investigate the correlation between the risk to sustain a structural cervical spine injury and vehicle-related impact severity parameters., Summary of Background Data: Impact severity parameters, such as the peak acceleration of the vehicle, its mean acceleration, and its velocity change, are often used to predict the whiplash injury risk or to objectify the patient's symptoms even though their correlation to injury is still not well understood., Methods: In a series of three in vitro experiments, a total of 18 human cadaveric cervical spine specimens were subjected to incremental side accelerations until structural injury occurred. While the duration of the acceleration pulse was kept constant throughout all three experiments, its shape was varied: In Experiment I, the acceleration pulse had a fast increase up to the maximum value and a fast decrease down to zero (fast-fast). Experiment II was characterized by a slow increase and fast decrease (slow-fast), and Experiment III was characterized by a fast increase and a slow decrease (fast-slow)., Results: The specimens of Experiment II (slow-fast) sustained structural injury at a significantly higher peak acceleration of the sled (4.6 g on average) than those of Experiments I (fast-fast) (2.6 g) and III (fast-slow) (3.1 g). In contrast, mean acceleration and velocity change of the injuring impacts were almost the same in all three experiments., Conclusion: The injury risk to the cervical spine was predictable by the mean acceleration of the sled and since the duration of the crash pulses was constant also by its velocity change but not by its peak acceleration.

Study Design: Retrospective data analysis., Objectives: To determine spinal injury patterns and clinical outcomes in patients involved in automotive accidents., Summary of Background Data: The records of 22,858 patients collected prospectively as part of the Trauma Audit Research Network (UK) Database (1993-2000)., Methods: Analysis of the records of 1121 motorcyclists and 2718 car occupants involved in automotive trauma., Results: Spinal injury occurred in 126 (11.2%) motorcyclists and 383 (14.1%) car occupants. Victims were predominantly young (mean ages: motorcycle 30.2 years, car 37.8 years) and male (motorcycle 88.9%, car 60.6%). The mean Injury Severity Scores were 18.8 and 15.1, respectively. Isolated spinal injuries occurred in 30 (23.8%) motorcyclists and 130 (33.9%) car occupants. The thoracic spine was most commonly injured in motorcyclists (54.8%), and the cervical spine was most commonly injured in car occupants (50.7%). Multiple regions were injured in 14 (10.3%) motorcyclists and 33 (8.5%) car occupants. Nine motorcyclists and 43 car occupants required spinal surgery. Median hospital stays were 11.5 days (range 0-235 days) and 10 days (range 0-252 days) in the motorcyclists and car occupants, respectively. There were 13 (10.3%) motorcycle- and 26 (6.8%) car-related deaths., Conclusion: Spinal injury patterns may reflect differing mechanisms of injury between the restrained car occupant and unrestrained motorcyclist. The motorcyclists were more severely injured, had more extremity trauma, a higher mortality rate, and a spinal injury pattern consistent with forced hyperflexion of the thoracic spine. The predominance of cervical injuries and higher incidence of neck and facial injuries in car occupants may reflect abdominothoracic seat belt restraint. The high frequency of multilevel injuries reaffirms the need for vigilance in patient assessment.

Study Design: Digital fluoroscopy was used to evaluate the motion in normal men during helmet and shoulder pad removal., Objectives: To observe the amount of motion that occurs during the removal of helmet and shoulder pads in an uninjured spine., Summary of Background Data: Removal of shoulder pads and helmet from a football player with suspected cervical spine injury can be particularly hazardous. Previous studies have been performed in cadavers with known created injuries. No control study in uninjured players has been done to show if there is similar motion with removal of football equipment., Methods: Four people removed the helmet and shoulder pads with a technique consistent with that described by the National Athletic Trainers' Association (NATA). Before positioning, with the helmet and shoulder pads on the subject and the subject lying flat on the table, one static lateral image was obtained as a baseline. With the neck stabilized and everyone in position, the torso, head, and neck were elevated approximately 30-40 degrees off the table bending at the waist. After elevation, continuous fluoroscopy was turned on as the helmet and shoulder pads were removed. Once the equipment was removed, the subject was carefully placed back down on the table and a final static lateral image was obtained. All images were saved digitally. Measurements were made for change in angulation, translation, distraction, and space available for the cord., Results: The results for change in disc height, translation, and space available for the cord showed no significant change. The results for change in angulation also did not show any significant motion in either flexion or extension from baseline or between each step in the protocol., Conclusions: In the conscious player with no cervical injury the protocol used by the NATA is effective in limiting cervical motion.

Study Design: An experimental investigation of intervertebral foramen and spinal canal neural space integrity was performed throughout physiologic range of motion of the lower cervical spine in intact human cadaver specimens., Objective: To investigate cervical positions that might place the neural tissues of the spine in heightened risk of injury. To meet this objective the following hypotheses were tested: 1) spinal canal integrity varies with specific normal range of motion positions of the lower cervical spine, and 2) intervertebral foramen integrity is dependent on and unique for different physiologic positions of the lower cervical spine., Summary of Background Data: Cervical spine injuries are frequently associated with compressive damage to neurologic tissues and consequently poor clinical outcomes. Neurologic injury typically occurs from disc, ligamentous, or bony occlusion of the spinal canal and intervertebral foraminal spaces dynamically during an injury event or with abnormal alignment and position after the injury event. Prior studies have shown pressure and geometric changes in cervical spine neural spaces in certain cervical spine positions. However, to the authors' knowledge, this is the first research effort aimed at elucidating the integrity of the cervical spine neural spaces throughout the normal physiologic range of motion., Methods: The authors instrumented 17 fresh-frozen unembalmed cadaveric human cervical spines (C3-C7) with specially designed intervertebral foramen occlusion transducers and a spinal canal occlusion transducer. The specimens were loaded with pure bending moments to produce simulated physiologic motions of the lower cervical spine. The resulting occlusion profiles for the intervertebral foramen and spinal canal were recorded along with the 6-degree of freedom position of the cervical spine. Because these occlusion measurements describe the ability of the spine to preserve the space for the neural structures, the authors define this neuroprotective role of the vertebral column as neural space integrity., Results: The range of motion developed experimentally in this study compared well with published reports of normal cervical motion. Thus, subsequent changes in neural space integrity may be regarded as resulting from normal human cervical spine motion. No significant change in the spinal canal space was detected for any physiologic motion; however, intervertebral foramen integrity was significantly altered in extension, ipsilateral bending, combined ipsilateral bending and extension, and combined contralateral bending with extension when compared with intact upright neutral position., Conclusions: This study defines the range of neural space integrity associated with simulated physiologic motion of the lower cervical spine in an experimental setting. This information may be useful in comparing neural space changes in pathologic conditions and may enhance refinement of neurologic injury prevention strategies.

Study Design: A case report of traumatic atlanto-occipital dislocation managed by transarticular screw fixation., Objectives: To present a case with initial failed wire fixation but successful reduction and fixation with transarticular screw fixation and occipitocervical plate stabilization., Summary of Background Data: Atlanto-occipital dislocation is generally a fatal injury, except when it occurs in children. Management of this injury is difficult because of multidirectional instability and the problems associated with technical stabilization., Methods: Intraoperative atlanto-occipital reduction was achieved and maintained by direct C0-C1 transarticular screw fixation. To protect this fixation, a posterior occipitocervical fusion at C0-C2 using a Y-plate was performed., Results: The internal fixation and reduction were maintained, indicating a good surgical outcome, at examination 2 years after surgery. The initially severe neurologic deficit was reduced to some motor weakness of the right hand and weakness of oculomotor function., Conclusions: Anatomic reduction and reliable fixation with transarticular screws may provide satisfactory clinical results with important neurologic recovery in cases of atlanto-occipital dislocation.

Study Design: Two-part study. Part One: the analysis of surveys distributed to members of the Orthopaedic Trauma Association (OTA) and 1000 surgeon members of NASS. Part Two: a prospective clinical study evaluating a new algorithm to evaluate the cervical spine in polytrauma patients., Objectives: To determine if there is a consensus of the optimal method for "clearing the cervical spine"; to assess the safety and efficacy of a newly proposed algorithm., Summary of Background Data: There is no uniformly accepted algorithm for "clearing the cervical spine" in the polytrauma patient or those patients with altered mental status secondary to the influence of alcohol, drugs or a closed head injury., Methods: All members of the OTA and 1000 surgeon members of NASS were sent questionnaires to assess their methods of "clearing the cervical spine" in the polytrauma patient. Their answers were collated, analyzed and compared to standard ATLS protocol guidelines. A new protocol, which includes a surgeon, controlled stretch test and flouroscopically visualized flexion-extension views, was initiated and evaluated for safety and efficacy., Survey: Fifty-five percent of the members of the OTA and 31% of the NASS surgeons responded to the questionnaire. Among the responses from the NASS members, the ratio of orthopaedic spine surgeons to neurosurgeons accurately parallels the society's membership (77% ortho, 23% neuro). Sixty-nine of the OTA and 54% of the NASS responders replied that they followed ATLS guidelines. Analysis of their responses showed only 40% compliance. Eighty-one percent of the OTA respondents utilize the standard three view cervical spine trauma series, only 31% of the NASS members adhere to this guideline. Nearly 90% of all respondents identified the presence of neck pain or retropharygeal soft tissue swelling as an indicator to expand their initial radiographic evaluation. There was no consensus as to management of the polytrauma patient with a closed head injury. Eighty-two percent of all respondents has seen or treated a purely ligamentous injury of the c-spine. SPECTIVE STUDY: Prospective clinical protocol. 35-month period: enrolled 153 patients, 12,000 patients seen in trauma unit. Completed data 149/153. 8/153 unable to be cleared due to poor visualization of cervical-thoracic junction. 3/153 positive findings identified during fluoro examination. All three instability patterns verified in surgery (true positives). No untoward events to date., Conclusions: A standardized protocol to safely and effectively clear the cervical spine has yet to be established. Preliminary results of a new protocol to safely evaluate the cervical spine in the polytrauma patient are promising.

Study Design: An experimental porcine study in which functional lumbar spinal units were tested in compression to failure. Biomechanical, radiographic, magnetic resonance imaging, and histological characteristics are described., Objectives: To explain the different patterns of injury seen in adults and adolescents resulting from traumatic injury to the vertebrae and to explain the mechanism behind traumatic displacement of the ring apophysis seen in athletes., Summary of Background Data: Recent investigations of the spine in adolescent who have sustained trauma have shown injuries to the growth zone, whereas studies of adults have shown injuries to the vertebral body. A higher frequency of abnormalities in the discs, the vertebral bodies, the endplates, and the ring apophyses has been demonstrated in athletes with high loads on the spine. There is controversy over the etiology of these changes., Methods: Twelve functional lumbar spinal units (vertebra-disc-vertebra) obtained from six young male pigs were tested in compression to failure. All units were examined with plain radiography and magnetic resonance imaging before and after compression. After the compression, histologic samples were taken from the injury site., Results: Identical traumatic changes were seen in all functional lumbar spinal units, i.e., fracture in the endplate through the growth zone posteriorly and displacement of the anulus fibrosus with a bony fragment at the point of insertion of the vertebra. The nucleus pulposus was ruptured and displaced through the fracture line in all cases. The injuries were not seen on radiographs but were detected on magnetic resonance images, as confirmed on microscopic and histologic examination., Conclusion: This study shows that the weakest part of the lumbar spine of the juvenile pig, when compressed, is the growth zone and the junction between the point of insertion of the anulus fibrosus and the vertebra. This location of weakness may explain the high frequency of disc degeneration and "persisting apophysis" seen in the spine of athletes.

Study Design: The authors developed a diagnostic double-blindfolded survey using placebo-controlled local anesthetic blocks., Objective: To determine the prevalence of cervical zygapophysial joint pain among patients with chronic neck pain (more than 3 months' duration) after whiplash injury., Summary of Background Data: The prevalence of cervical zygapophysial joint pain after whiplash has been studied by means of comparative local anesthetic blocks. The concern is that such blocks may be compromised by placebo responses and that prevalence estimates based on such blocks may exaggerate the importance of this condition., Methods: Sixty-eight consecutive patients referred for chronic neck pain after whiplash were studied. Patients with dominant headache were first screened with the use of comparative blocks of the C2-C3 zygapophysial joint. Patients who had positive responses concluded investigations. Those who did not experience pain relief together with the patients with dominant neck pain proceeded to undergo placebo-controlled local anesthetic blocks. Two different local anesthetics and a placebo injection of normal saline were administered in random order and under double-blindfolded conditions. A positive diagnosis was made if the patient's pain was completely and reproducibly relieved by each local anesthetic but not by the placebo injection., Results: Among patients with dominant headache, comparative blocks revealed that the prevalence of C2-C3 zygapophysial joint pain was 50%. Among those without C2-C3 zygapophysial joint pain, placebo-controlled blocks revealed the prevalence of lower cervical zygapophysial joint pain to be 49%. Overall, the prevalence of cervical zygapophysial joint pain (C2-C3 or below) was 60% (95% confidence interval, 46%, 73%)., Conclusion: Cervical zygapophysial joint pain is common among patients with chronic neck pain after whiplash. This nosologic entity has survived challenge with placebo-controlled, diagnostic investigations and has proven to be of major clinical importance.

Study Design: This study analyzed the role of exposure to driving and other covariates in reports of back, neck, and shoulder pain and resultant disability. Cohorts in Sweden and the United States were compared., Objectives: To establish the effect of mechanical and psychosocial factors in reporting back, neck, and shoulder pain and work loss., Summary of Background Data: There are numerous reports of a positive relationship between back pain and driving. However, exposure data are minimal. The influence of job satisfaction has not been assessed., Methods: The physical factors affecting reports of back, neck, and shoulder pain were investigated in a two-country cohort study of bus and truck drivers and sedentary workers. Vibration exposure was obtained by directly measuring the vibration imposed on the driver during a typical work day. Lifting exposure was attained by questionnaire. Cumulative exposure was computed based on work history. Musculoskeletal health information was based on a modified nordic questionnaire, and other questionnaires recorded the physical and psychosocial aspects of the work environment., Results: Of the sample, 50% reported low back pain, with no difference between countries. The highest risk factors (odds ratios) for back and neck pain were long-term vibration exposure, heavy lifting, and frequent lifting. A combination of long-term vibration exposure and frequent lifting carried the highest risk of low back pain. Work loss from low back pain was influenced by perceived job stress., Conclusions: Vibration (resulting from driving) and lifting cause back, neck, and shoulder pain, whereas inability to work seems affected by stress at work.

This study was conducted to determine the relationship between intraosseous pressure and vertebral microtrauma in the lumbar spine. Functional spinal units were excised from human cadavers. Radio-opaque dye was injected into the nucleus. Miniature transducers were inserted into the vertebrae to record intraosseous pressures. Compressive loading was applied quasistatically (2 mm/sec) until injury occurred. Movement of the contrast medium was monitored under fluoroscopy. The subchondral endplate was the most vulnerable component for initiation of injury to the lumbar spine segment. In the initial stages of loading, the vertebral endplates gradually bulged outward, with the contrast medium staying within the nucleus. However, at higher physiologic load levels, before reaching the limiting load, the deformations increased, resulting in buckling of one of the endplates. This was followed by the contrast medium impregnating the spongiosa. Microlevel trauma was not observed radiographically after load removal, indicating that one cannot always equate a normal radiograph with normal spinal anatomy. Mean forces, deformations, stiffnesses, energies, and strains were 7.8 kN (+/- 1.4), 5.23 mm (+/- 0.78), 1940 N/mm (+/- 226), 18.7 J (+/- 4.4), and 35.5% (+/- 3.7), respectively. Pressure in the vertebral body containing the injured endplate before the onset of microtrauma was different (P < 0.05) from the pressure after injury; the pressures in the body containing the intact endplate, however, were not statistically different. Significant differences (P < 0.05) in the intraosseous pressures occurred between the two spinal levels at low-level physiologic loads before the onset of microtrauma.(ABSTRACT TRUNCATED AT 250 WORDS)

A review of 277 patients under the age of 16 years admitted to the pediatric spinal injury unit at Rancho Los Amigos Medical Center from 1960 to 1989 showed that 70% of the patients were male; complete and incomplete injuries were about equal; and the average age was 8.8 years. The cause of spinal injury by time period revealed that earlier time periods had etiologies similar to those reported in previously published series. Although the incidence of these traditional causes remained constant, violent injuries by gunshot steadily increased with time. In the most recent 5-year period, gunshot wounds equaled motor vehicle injuries as the most frequent cause of a child's spinal injury admitted to this hospital. Gunshot wound victims averaged 12 years old, 80% were male, and most were thoracic level paraplegics. Half of the 50 adolescents (12-16 years old) injured during the last 5 years were gunshot victims.

The threshold for flexion-distraction injuries was determined on lumbar functional spinal units exposed to a combined flexion-shear load in the sagittal plane. The specimens could resist a bending moment of 121 Nm and a shear force of 486 N at the first sign of a permanent deformation of the osteoligamentous components, which occurred at 78% of the assumed ultimate strength of each specimen. The flexion angulation was 16 degrees. The bone mineral content determined in adjacent vertebrae by means of dual photon absorptiometry was an accurate predictor of structural properties of the entire functional spinal unit even at the first sign of a substantial structural injury and not only at ultimate failure as previously demonstrated.

Three patients with the unusual manifestation of atlantoaxial subluxation in Reiter's syndrome are studied. Each patient had mild symptoms referable to the cervical spine and radiologic evidence of erosive disease elsewhere in the skeleton. One patient had an 11-year history of Reiter's syndrome when the atlantoaxial subluxation was detected. The other two had atlantoaxial subluxation detected within 1 year of initial presentation, at variance with three other such patients that were reported previously, in whom there was a 6- to 10-year interval from initial presentation until radiographic documentation of atlantoaxial subluxation. Cervical spine radiographs, including flexion and extension views, are recommended for all patients with Reiter's syndrome and cervical spine symptoms.

The cases of 42 patients with low-velocity gunshot wounds to the spine with an associated perforated viscus were reviewed. All viscus perforations occurred prior to the spinal injury. There were a total of 51 perforations, including 14 of the colon, 15 of the small bowel, 15 of the stomach, five of the esophagus, and two of the pharynx. All patients had significant neurologic deficits, with 23 patients suffering a complete neurologic injury. Average clinical follow-up was 18 months (range: 4-64 months). Only three patients developed documented spinal or paraspinal infections. One case of acute meningitis occurred after an isolated stomach perforation, while two other patients developed psoas abscesses after colon injuries. The roles of initial antibiotic therapy and of early bullet removal were evaluated in regard to infection. An extended course of broad spectrum antibiotics combined with bedrest appeared to significantly reduce the risk of spinal or paraspinal infection as compared with a previous study. Early bullet removal did not appear to be a significant factor in the prevention of infection. Prospective studies are needed to accurately delineate the role of initial antibiotic therapy for the prevention of spinal infection in these injuries.