Glass Fragment Injury to the Craniocervical Junction with Interatlantooccipital Penetration to the Subarachnoid Space: Not-To-Be-Missed Important Aspects of Craniocervical Trauma Even in the Middle of the COVID-19 Pandemic: Case Report and Review of Literature.

BACKGROUND: Nonmissile penetrating injuries to the craniocervical junction caused by a glass fragment are rare, and a standard management strategy has not been established. CASE DESCRIPTION: A 75-year-old Japanese man was brought into our emergency department after receiving a left retroauricular stab wound by broken glass fragments. After spinal immobilization, a computed tomography (CT) scan revealed glass fragments penetrating at the right craniocervical junction to the interatlantooccipital subarachnoid space. CT angiography showed that both vertebral arteries were not injured. Magnetic resonance imaging demonstrated that the glass fragments did not penetrate the cervical cord or medulla oblongata. These glass fragments were removed via a midline incision from the external occipital protuberance to the C7 and with laminectomy without suboccipital craniectomy. Five of the glass fragments were found and removed in total. The dural defect was patched with a free fascia autograft. His postoperative course was uneventful. Postoperative CT angiography showed that both vertebral arteries were intact and the glass fragments had been removed completely. CONCLUSIONS: CT graphical diagnosis is useful for the management of penetrating craniocervical junction trauma, and it should be considered in the evaluation of patients who have suffered craniocervical penetrating injury even in the absence of major wounds or bleeding. Spinal immobilization of patients with craniocervical penetrating injuries is crucial to avoid not only secondary neurologic damage but also secondary critical vascular damage. Incomplete or inadequate assessment of craniocervical stab wounds results in unexpected hazards that are preventable.

Radiologic predictors of in-hospital mortality after traumatic craniocervical dissociation.

BACKGROUND: Traumatic craniocervical dissociation (CCD) is the forcible dislocation of the skull from the vertebral column. Because most CCD patients die on scene, prognostication for those who arrive alive to hospital is challenging. The study objective was to determine if greater dissociation, based on radiologic measurements of CCD, is predictive of in-hospital mortality among patients surviving to the emergency department. METHODS: All trauma patients arriving to our Level 1 trauma center (January 2008 to April 2019) with CCD were retrospectively identified and included. Transfers and patients without computed tomography head/cervical spine were excluded. Study patients were dichotomized into groups based on in-hospital mortality. Radiologic measurements of degree of CCD were performed based on the index computed tomography scan by an attending radiologist with Emergency Radiology fellowship training. Measurements were compared between patients who died in-hospital versus those who survived. RESULTS: After exclusions, 36 patients remained: 12 (33%) died and 24 (67%) survived. Median age was 55 years (30-67 years) versus 44 (20-61 years) (p = 0.199). Patients who died had higher Injury Severity Score (39 [31-71] vs. 27 [14-34], p = 0.019) and Abbreviated Injury Scale head/neck score (5 [5-5] vs. 4 [3-4], p = 0.001) than survivors. The only radiologic measurement that differed between groups was greater soft tissue edema at mid C1 among patients who died (12.37 [7.60-14.95] vs. 7.86 [5.25-11.61], p = 0.013). Receiver operating characteristic curve analysis of soft tissue edema at mid C1 and mortality revealed 10.86 mm or greater of soft tissue width predicted mortality with sensitivity and specificity of 0.75. All other radiologic parameters, including the basion-dens interval, were comparable between groups (p > 0.05). CONCLUSION: Among patients who arrive alive to hospital after traumatic CCD, greater radiologic dissociation is not associated with increased mortality. However, increased soft tissue edema at the level of mid C1, particularly 10.86 mm or greater, is associated with in-hospital death. These findings improve our understanding of this highly lethal injury and impart the ability to better prognosticate for patients arriving alive to hospital with CCD. LEVEL OF EVIDENCE: Prognostic and Epidemiological, Level III.

Magnetic resonance imaging of cervical ligamentous anatomy and traumatic ligamentous injuries.

Cervical spine trauma accounts for majority of spinal injuries, and approximately one-third involve the craniocervical junction (CCJ). Due to its high sensitivity, magnetic resonance imaging (MRI) has become the standard tool for imaging suspected ligamentous injuries in an unstable spine and in patients with neurological deficits having a normal CT. The ligamentous anatomy of the CCJ is complex, and thorough knowledge is a prerequisite for accurate interpretation of the MRI findings. This pictorial essay aims to familiarise radiologists with the ligamentous anatomy, mechanisms of injury and MRI appearances of injuries in the cervical spine, with emphasis on the CCJ.

Magnetic resonance imaging of enhanced nerve repair with mesenchymal stem cells combined with microenvironment immunomodulation in neurotmesis.

INTRODUCTION: The immuno-microenvironment of injured nerves adversely affects mesenchymal stem cell (MSC) therapy for neurotmesis. Magnetic resonance imaging (MRI) can be used noninvasively to monitor nerve degeneration and regeneration. The aim of this study was to investigate nerve repair after MSC transplantation combined with microenvironment immunomodulation in neurotmesis by using multiparametric MRI. METHODS: Rats with sciatic nerve transection and surgical coaptation were treated with MSCs combined with immunomodulation or MSCs alone. Serial multiparametric MRI examinations were performed over an 8-week period after surgery. RESULTS: Nerves treated with MSCs combined with immunomodulation showed better functional recovery, rapid recovery of nerve T2, fractional anisotropy and radial diffusivity values, and more rapid restoration of the fiber tracks than nerves treated with MSCs alone. DISCUSSION: Transplantation of MSCs in combination with immunomodulation can exert a synergistic repair effect on neurotmesis, which can be monitored by multiparametric MRI.

Skull Base-related Lesions at Routine Head CT from the Emergency Department: Pearls, Pitfalls, and Lessons Learned.

Routine non-contrast material-enhanced head CT is one of the most frequently ordered studies in the emergency department. Skull base-related pathologic entities, often depicted on the first or last images of a routine head CT study, can be easily overlooked in the emergency setting if not incorporated in the interpreting radiologist's search pattern, as the findings can be incompletely imaged. Delayed diagnosis, misdiagnosis, or lack of recognition of skull base pathologic entities can negatively impact patient care. This article reviews and illustrates the essential skull base anatomy and common blind spots that are important to radiologists who interpret nonenhanced head CT images in the acute setting. The imaging characteristics of important "do not miss" lesions are emphasized and categorized by their cause and location within the skull base, and the potential differential diagnoses are discussed. An interpretation checklist to improve diagnostic accuracy is provided. ©RSNA, 2019.

Rigid Internal Fixation for Traumatic Cranio-Cervical Dissociation in Infants and Young Children.

STUDY DESIGN: Retrospective review. OBJECTIVE: Evaluate radiographic and clinical outcomes for infants and children, who underwent rigid occipito-cervical fixation for traumatic craniocervical dissociation (tCCD). SUMMARY OF BACKGROUND DATA: Traumatic craniocervical dissociation is devastating. Children are at high risk but make up a large number of survivors. Non-rigid fixation has traditionally been favored over screw and rod constructs due to inherent challenges involved with instrumenting the pediatric craniocervical junction. Therefore, outcomes for rigid occipito-cervical instrumentation in infants and young children with tCCD remain uncertain. METHODS: Retrospective review of children who survived tCCD between 2006 and 2016 and underwent rigid occipito-cervical fixation. RESULTS: Fifteen children, from 8 months to 8 years old (mean, 3.8 yr), were either a passenger (n = 11) or a pedestrian (n = 4) in a motor vehicle accident. Seven patients had weakness: five with quadriplegia, one with hemiparesis, and one with bilateral upper extremity paresis. Ten patients had concurrent C1-2 instability. At last follow-up, four patients had improved motor function: one with bilateral upper extremity paresis and one with hemiparesis regained full strength, one with quadriplegia regained function on one side while another regained function in bilateral upper extremities. All underwent rigid posterior occipito-cervical fixation, with two patients requiring additional anterior and posterior fixation at non-contiguous levels. Fourteen patients were stable on flexion-extension x-rays at a mean follow-up of 31 months (9-1 yr or longer, 7-2 yr or longer). There were no cases of deformity, growth disturbance, or subaxial instability. CONCLUSION: Children who survive tCCD may regain function after stabilization. Rigid internal rod and screw fixation in infants and young children safely provided long-term stability. We advocate using C2 translaminar screws to exploit the favorable anatomy of pediatric lamina to minimize the risks of occipitocervical (OC) instrumentation. LEVEL OF EVIDENCE: 4.

Unión cráneo-cervical - anatomía normal y correlación con imágenes / Cranio Cervical Junction - Anatomy and Imaging Correlation

La solicitud de estudios de imagen en pacientes con trauma cervical es muy frecuente en la práctica diaria. Esa patología es causa relativamente frecuente de discapacidad en pacientes jóvenes junto con el trauma encéfalo craneano. En un porcentaje no despreciable de los casos, las lesiones traumáticas comprometen la unión cráneo- cervical y en esos pacientes, la morbi-mortalidad es más significativa. La transición entre el cráneo y el raquis se basa en un conjunto de estructuras óseas relacionadas por articulaciones muy móviles y estabilizadas por un grupo de ligamentos y músculos que le brindan al mismo tiempo gran solidez. Para una correcta interpretación de los estudios de imagen de uso corriente en la clínica, es fundamental un sólido conocimiento anatómico de la unión cráneo-cervical y sus componentes. Es el objetivo de esta revisión, sistematizar la anatomía de la unión cráneo-cervical con especial énfasis en sus ligamentos, analizar la fisiología de sus movimientos y el concepto de estabilidad para luego realizar una correlación con tomografía computada multi-detector y resonancia magnética.

The request of imaging techniques in patients with cervical spine trauma is very common in clinical practice. Cervical trauma is a relatively common cause of disability in young patients. In a significant percentage of cases traumatic injuries compromise the cranio-cervical junction with more important morbidity and mortality in this group of patients. The transition between the skull and the spine is based on a set of bony structures, high mobility joints, and stabilization mechanism formed by a group of ligaments and muscles. A solid anatomical knowledge of the cranio-cervical junction and its components is essential for a correct interpretation of current high resolution imaging studies. The goal of this review is highlight the anatomy of the cranio-cervical junction with special emphasis on the ligaments, analyze the biomechanics of their movements and the concept of stability. At last but not leastwe will establish a correlation with multidetector computed tomography and high-resolutionmagnetic resonance imaging.

Diffusion MRI in acute nervous system injury.

Diffusion weighted magnetic resonance imaging (DWI) and related techniques such as diffusion tensor imaging (DTI) are uniquely sensitive to the microstructure of the brain and spinal cord. In the acute aftermath of nervous system injury, for example, DWI reveals changes caused by injury that remains invisible on other MRI contrasts such as T2-weighted imaging. This ability has led to a demonstrated clinical utility in cerebral ischemia. However, despite strong promise in preclinical models and research settings, DWI has not been as readily adopted for other acute injuries such as traumatic spinal cord, brain, or peripheral nerve injury. Furthermore, the precise biophysical mechanisms that underlie DWI and DTI changes are not fully understood. In this report, we review the DWI and DTI changes that occur in acute neurological injury of cerebral ischemia, spinal cord injury, traumatic brain injury, and peripheral nerve injury. Their associations with the underlying biology are examined with an emphasis on the role of acute axon and dendrite beading. Lastly, emerging DWI techniques to overcome the limitations of DTI are discussed as these may offer the needed improvements to translate to clinical settings.

Isolated Traumatic Diastasis of the Clival Synchondroses without Clival Fracture.

Traumatic clival fractures in the pediatric population are associated with high mortality rates. In our previously reported series, a subset of clival fractures were associated with traumatic diastasis of the surrounding clival synchondroses. Herein, we describe a pediatric case of an isolated traumatic diastasis of the clival synchondroses without clival fracture with significant injury to neurovascular structures. To our knowledge this is the first report to describe this entity. Careful radiological attention should be made towards the clival synchondroses in crushing head injuries to best tailor screening for cerebrovascular injury even in the absence of clival fractures.

Occipital Condyle Fracture Extending to the Inferior Part of the Clivus.

Although rarely reported in the literature, serious occipital and condylar fractures have been diagnosed more often with the widespread use of computed cranial tomography in traumas. In this paper, a 16-year-old female with a left occipital fracture extending from the left occipital condyle anterior of the hypoglossal canal to the inferior part of the clivus is presented. The fracture which had caused a neurological deficit was cured with conservative treatment. For delayed hypoglossal nerve paralysis due to swelling within the canal, methylprednisolone was started, and a complete cure was attained in about 10 days. Traumatic damage of bony structures of the condyle and clivus at the junction of many vital nerves, vessels, and ligaments may lead to traumatic deficit and death.

Ultrasonographic demonstration of intraneural neovascularization after penetrating nerve injury.

INTRODUCTION: Hypervascularization of nerves has been shown to be a pathological sign in some peripheral nerve disorders, but has not been investigated in nerve trauma. METHODS: An observational cohort study was performed of the intraneural blood flow of 30 patients (34 nerves) with penetrating nerve injuries, before or after nerve reconstruction. All patients underwent electrophysiological assessment, and B-mode and color Doppler ultrasonography. RESULTS: Intraneural hypervascularization proximal to the site of injury was found in all nerves, which was typically marked and had a longitudinal extension of several centimeters. In 6 nerves, some blood flow was also present within the injury site or immediately distal to the injury. No correlation was found between the degree of vascularization and age, size of the scar / neuroma, or degree of reinnervation. DISCUSSION: Neovascularization of nerves proximal to injury sites appears to be an essential element of nerve regeneration after penetrating nerve injuries. Muscle Nerve 57: 994-999, 2018.

The "pseudo-CT myelogram sign": an aid to the diagnosis of underlying brain stem and spinal cord trauma in the presence of major craniocervical region injury on post-mortem CT.

AIM: To document the detection of underlying low-attenuation spinal cord or brain stem injuries in the presence of the "pseudo-CT myelogram sign" (PCMS) on post-mortem computed tomography (PMCT). MATERIALS AND METHODS: The PCMS was identified on PMCT in 20 decedents (11 male, nine female; age 3-83 years, mean age 35.3 years) following fatal blunt trauma at a single forensic centre. Osseous and ligamentous craniocervical region injuries and brain stem or spinal cord trauma detectable on PMCT were recorded. PMCT findings were compared to conventional autopsy in all cases. RESULTS: PMCT-detected transection of the brain stem or high cervical cord in nine of 10 cases compared to autopsy (90% sensitivity). PMCT was 92.86% sensitive in detection of atlanto-occipital joint injuries (n=14), and 100% sensitive for atlanto-axial joint (n=8) injuries. PMCT detected more cervical spine and skull base fractures (n=22, and n=10, respectively) compared to autopsy (n=13, and n=5, respectively). CONCLUSION: The PCMS is a novel description of a diagnostic finding, which if present in fatal craniocervical region trauma, is very sensitive for underlying spinal cord and brain stem injuries not ordinarily visible on PMCT. Its presence may also predict major osseous and/or ligamentous injuries in this region when anatomical displacement is not evident on PMCT.

Classification and Management of Pediatric Craniocervical Injuries.

This article addresses the key features, clinical presentation, patterns of injury, indicated workup, and radiographic findings associated with craniocervical injuries in the pediatric population. It discusses nonsurgical and surgical management of pediatric cervical spine trauma, addressing when each is indicated, and the various techniques available to the pediatric neurosurgeon.

Retrospective analysis of a case series of patients with traumatic injuries to the craniocervical junction / Análise retrospectiva de série de casos com lesões traumáticas da junção craniocervical

ABSTRACT Objective To evaluate the correlation between the treatment, the characteristics of the lesions and the clinical outcome of patients with traumatic injuries to the craniocervical junction. Methods This was a retrospective study of patients treated conservatively or surgically between 2010 and 2013 with complete data sets. Results We analyzed 37 patients, 73% were men with mean age of 41.7 years. Of these, 32% were submitted to initial surgical treatment and 68% received conservative treatment. Seven (29%) underwent surgery subsequently. In the surgical group, there were seven cases of odontoid type II fractures, two cases of fracture of posterior elements of the axis, one case of C1-C2 dislocation with associated fractured C2, one case of occipitocervical dislocation, and one case of combined C1 and C2 fractures, and facet dislocation. Only one patient had neurological déficit that improved after treatment. Two surgical complications were seen: a liquoric fistula and one surgical wound infection (reaproached). In the group treated conservatively, odontoid fractures (eight cases) and fractures of the posterior elements of C2 (five cases) were more frequent. In two cases, in addition to the injuries of the craniocervical junction, there were fractures in other segments of the spine. None of the patients who underwent conservative treatment presented neurological deterioration. Conclusion Although injuries of craniocervical junction are relatively rare, they usually involve fractures of the odontoid and the posterior elements of the axis. Our results recommend early surgical treatment for type II odontoid fractures and ligament injuries, the conservative treatment for other injuries.

RESUMO Objetivo Avaliar a correlação entre o tratamento, as características das lesões e o resultado clínico em pacientes com lesões traumáticas na junção craniocervical. Métodos Estudo retrospectivo de pacientes maiores de 18 anos tratados de forma conservadora ou cirúrgica, entre 2010 e 2013. Resultados Foram analisados 37 pacientes, 73% eram do sexo masculino e a média de idade foi de 41,7 anos. Inicialmente 32% dos pacientes foram submetidos a tratamento cirúrgico, e 68% foram submetidos a tratamento conservador. Sete pacientes (29%) do grupo conservador foram submetidos posteriormente à cirurgia. No grupo cirúrgico, houve sete casos de fratura de odontóide tipo II, dois casos de fratura de elementos posteriores do áxis, um caso de luxação C1-C2, um caso de deslocamento occipito-cervical e um caso de fraturas de C1 e C2 e luxação facetária. Um paciente apresentava déficit neurológico, melhorando após o tratamento. Houve duas complicações pós-cirúrgicas, uma fístula liquórica e uma infecção de ferida operatória (reabordada). No grupo conservador, predominaram as fraturas do odontóide (oito) e dos elementos posteriores de C2 (cinco). Em dois casos, havia também fraturas em outros segmentos da coluna. Nenhum dos pacientes deste grupo apresentou deterioração neurológica. Conclusão As lesões da junção craniocervical são raras, sendo mais frequentes as fraturas do odontóide e dos elementos posteriores do áxis. Nossos resultados recomendam o tratamento cirúrgico precoce para os pacientes com fraturas do odontóide tipo II e lesões ligamentares, e tratamento conservador para os demais pacientes.

Synthesis and characterization of an HSP27-targeted nanoprobe for in vivo photoacoustic imaging of early nerve injury.

Imaging is routinely used for clinical and diagnostic purposes, but techniques capable of high specificity and resolution for the early detection of nerve injury are still limited. In this study, we found that heat shock protein 27 (HSP27) becomes highly upregulated within 3 to 7 days of nerve injury. Taking advantage of this expression pattern, we conjugated gold nanorods (GNRs) to HSP27-specific antibodies to generate a nanoprobe (GNR-HSP27Abs) that could be targeted to the site of nerve injury and detected by near-infrared photoacoustic imaging. Notably, photoacoustic images acquired 12hours after local administration of GNR-HSP27Abs demonstrated that the nanoprobe can distinguish between injured and uninjured nerves in rats. Taken together, these findings expand the application of nanoprobe-targeted photoacoustic imaging to the detection of injured nerves, and prompt further development of this novel imaging platform for clinical application.

Retrospective analysis of a case series of patients with traumatic injuries to the craniocervical junction.

OBJECTIVE: To evaluate the correlation between the treatment, the characteristics of the lesions and the clinical outcome of patients with traumatic injuries to the craniocervical junction. METHODS: This was a retrospective study of patients treated conservatively or surgically between 2010 and 2013 with complete data sets. RESULTS: We analyzed 37 patients, 73% were men with mean age of 41.7 years. Of these, 32% were submitted to initial surgical treatment and 68% received conservative treatment. Seven (29%) underwent surgery subsequently. In the surgical group, there were seven cases of odontoid type II fractures, two cases of fracture of posterior elements of the axis, one case of C1-C2 dislocation with associated fractured C2, one case of occipitocervical dislocation, and one case of combined C1 and C2 fractures, and facet dislocation. Only one patient had neurological déficit that improved after treatment. Two surgical complications were seen: a liquoric fistula and one surgical wound infection (reaproached). In the group treated conservatively, odontoid fractures (eight cases) and fractures of the posterior elements of C2 (five cases) were more frequent. In two cases, in addition to the injuries of the craniocervical junction, there were fractures in other segments of the spine. None of the patients who underwent conservative treatment presented neurological deterioration. CONCLUSION: Although injuries of craniocervical junction are relatively rare, they usually involve fractures of the odontoid and the posterior elements of the axis. Our results recommend early surgical treatment for type II odontoid fractures and ligament injuries, the conservative treatment for other injuries. OBJETIVO: Avaliar a correlação entre o tratamento, as características das lesões e o resultado clínico em pacientes com lesões traumáticas na junção craniocervical. MÉTODOS: Estudo retrospectivo de pacientes maiores de 18 anos tratados de forma conservadora ou cirúrgica, entre 2010 e 2013. RESULTADOS: Foram analisados 37 pacientes, 73% eram do sexo masculino e a média de idade foi de 41,7 anos. Inicialmente 32% dos pacientes foram submetidos a tratamento cirúrgico, e 68% foram submetidos a tratamento conservador. Sete pacientes (29%) do grupo conservador foram submetidos posteriormente à cirurgia. No grupo cirúrgico, houve sete casos de fratura de odontóide tipo II, dois casos de fratura de elementos posteriores do áxis, um caso de luxação C1-C2, um caso de deslocamento occipito-cervical e um caso de fraturas de C1 e C2 e luxação facetária. Um paciente apresentava déficit neurológico, melhorando após o tratamento. Houve duas complicações pós-cirúrgicas, uma fístula liquórica e uma infecção de ferida operatória (reabordada). No grupo conservador, predominaram as fraturas do odontóide (oito) e dos elementos posteriores de C2 (cinco). Em dois casos, havia também fraturas em outros segmentos da coluna. Nenhum dos pacientes deste grupo apresentou deterioração neurológica. CONCLUSÃO: As lesões da junção craniocervical são raras, sendo mais frequentes as fraturas do odontóide e dos elementos posteriores do áxis. Nossos resultados recomendam o tratamento cirúrgico precoce para os pacientes com fraturas do odontóide tipo II e lesões ligamentares, e tratamento conservador para os demais pacientes.

Ultrasound evaluation of focal neuropathies in athletes: a clinically-focused review.

Focal neuropathies represent a rare but clinically important and potentially challenging aetiology of pain in athletes. Diagnostic ultrasound is commonly used in the evaluation of nerve entrapments, and has several advantages over other imaging modalities, including high resolution, portability, lack of ionising radiation, low cost, point-of-care access, ease of contralateral comparison and capability of Doppler and dynamic imaging techniques. In this review, we discuss the use of ultrasound for the evaluation of injuries to the brachial plexus including 'stingers,' suprascapular nerve, ulnar nerve, radial nerve, common fibular nerve, tibial nerve and interdigital nerves of the foot at selected common sites of entrapment.

The role of computed tomography for postoperative evaluation of percutaneous sacroiliac screw fixation and description of a "safe zone".

We sought to determine whether computed tomography (CT) is an accurate tool for evaluation of reduction, prediction of neurologic deficit, and evaluation of need for revision surgery in unstable pelvic ring injuries treated with percutaneous sacroiliac (SI) screw fixation and whether any neural foramen penetration violation is safe. Using medical records and radiographic data, we retrospectively evaluated 46 patients with 51 fractures or widenings of the SI joint that were surgically treated with percutaneous SI screw fixation, either alone or associated with anterior fixation. Using the Young and Burgess classification, there were 3 vertical shear injuries, 13 lateral compression injuries, 17 anterior-posterior injuries, 7 sacral fractures, and 6 combination or unclassifiable pelvic injuries. Satisfactory reduction was obtained in all cases. All patients had postoperative CT scans, and 23 of 51 screws had some foramen penetration with an average of 3.3 mm (range, 1.4-7.0 mm). After percutaneous screw fixation, 10 of 46 patients had postoperative neurologic deficit, 4 of which were unchanged from preoperative evaluation. Of the 6 patients with new or worsened neurologic deficit, CT showed neural foramen penetration of 2.1 and 7.0 mm in 2 patients. Both patients underwent screw revision, resulting in improved neurologic deficit. The remaining 4 patients did not have foramen penetration; their neurologic function improved, with full return at 6 weeks without screw removal. Neural foramen penetration documented with CT did not correlate with neurologic deficit unless the penetration was greater than 2.7 mm. Postoperative CT showing neural foramen penetration was the cause of revision surgery in 2 of 10 patients with postoperative neurologic deficit after percutaneous SI screw fixation. Based on these findings, we recommend postoperative CT only in those cases where there is new neurologic deficit and screw removal if foramen penetration is greater than 2.1 mm. We also describe a new "safe zone" for screw insertion encompassing the superior 2 mm of the sacral foramen with adequate pelvic reduction.