Sacral Segments Research Articles

Simplifying the Orientation of S1 Iliosacral Screws for Placement in the Dysmorphic Sacrum.

Determining the proper iliosacral screw orientation in a dysmorphic S1 sacral segment using a C-arm is difficult, and pelvic computed tomography (CT) is often necessary for the preoperative planning. On the preoperative pelvic axial CT section, the intended screw trajectory can be delineated intraosseously along the axis of the oblique osseous corridor. An inherently accurate orientation would be determined by 2 factors: (1) the trajectory is in the pelvic transverse plane, and (2) it is oriented relative to the coronal plane at a patient-specific angle, which should be measured preoperatively. Based on the above reasoning, we aimed to simplify and verify the orientation. After establishing the starting point on the sacral lateral view, we tested a method of simplifying the guidewire orientation: placing the guidewire in the pelvic transverse plane and then manipulating it to be angled relative to the coronal plane at the preoperatively measured patient-specific angle. The guidewire orientation should then be reproducibly accurate on the pelvic outlet and inlet views. The feasibility and safety of our method were verified through computer-simulated virtual surgical procedures in 95 dysmorphic sacra and clinical surgical procedures in 12 patients. The primary outcome parameters were the guidewire orientation and screw placement accuracy. Using our method, the S1 guidewire orientation was reproducibly accurate on the pelvic outlet and inlet views in all of the virtual and clinical surgical procedures. Ninety-five virtual S1 screws (1 screw in each left hemipelvis) were placed intraosseously in the pelvic transverse plane. Fourteen unilateral S1 screws were placed intraosseously in the pelvic transverse plane in the 12 patients (2 patients had double screws) without iatrogenic injuries. The guidewire orientation can be simplified by placing the guidewire in the pelvic transverse plane and replicating the preoperatively measured patient-specific angle between the guidewire and the coronal plane. After establishing the starting point on the sacral lateral view, our simplified manipulation yields a reproducibly accurate orientation on the pelvic outlet and inlet views. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The classification of sacral foramina in a South African sample using cadaveric and osteological remains

Sacroiliac (SI) joint fixation is a technique used for SI joint fractures, SI joint dislocations and sacral fractures. Sacral screws can be placed either into the S1 or the S2 vertebrae if S1 is insufficient. Malpositioning of the screws is a common surgical complication as sacral variations exists amongst populations. Complications associated with the misposition of screws can lead to injury of the sacral venous plexus, iliac vessels, or sacral nerve roots. Therefore, this study aimed to evaluate sacral variations in a South African sample by determining distances between the first and second sacral foramina and classifying the common types of sacra found.A quantitative cross-sectional comparative study was conducted. One hundred and twenty (n = 120) dry human sacra and 11 formalin-fixed cadavers were measured to determine the linear distances between the first two anterior and posterior sacral foramina. Additionally, the dry human sacra were classified according to Mahato's classification system. A cadaver SI joint fixation simulation was performed by an orthopaedic surgeon.The mean sacral promontory height was found to be 31.81 mm and 37.52 mm in osteological and cadaver specimens, respectively. The mean anterior pedicle height was significantly different for the left (18.81 mm) and right (21.67 mm) side measurements. A statistically significant difference was found between cadavers and osteological samples for all measurements taken. In the osteological sample, ancestry and age mostly influenced the variations noted.Using Mahato's classification system, sacra with five sacral segments, auricular surfaces extending from the superior part of S1 to the middle of S3 and no accessory L5/S1 articulations had the highest prevalence of 59.17 %.The South African sample exhibited similarities but did not fully compare to other populations. The results in this study should be considered as a reference for surgeries involving the SI joint and sacral foramina. However, where possible, the exact anatomy with possible variations of the patient should be evaluated preoperatively using X-rays and angiograms.

Comparison of intravenous dexmedetomidine versus ketamine-dexmedetomidine combination on spinal block characteristics in patients undergoing lower limb orthopaedic surgery - A randomised clinical trial.

One major limitation of the spinal block remains the inability to extend the duration of the block intraoperatively unless planned before with spinal or epidural catheters and/or intrathecal additives. This study was designed to compare the effects of intravenous dexmedetomidine versus low-dose ketamine-dexmedetomidine combination infusion on spinal anaesthesia in lower limb orthopaedic surgeries. This randomised study was conducted in 60 patients scheduled for unilateral lower limb surgeries under spinal anaesthesia. Patients were randomised into Group D (n = 30) (0.5 µg/kg of intravenous (IV) dexmedetomidine bolus followed by maintenance infusion at 0.5 µg/kg/h) and Group LKD (n = 30) (IV bolus of 0.5 µg/kg of dexmedetomidine and 0.2 mg/kg of ketamine, followed by maintenance infusions of dexmedetomidine and ketamine at 0.5 µg/kg/h and 0.2 mg/kg/h, respectively). Ramsay Sedation Scale score of 3-4 was maintained. The t-test or the Wilcoxon-Mann-Whitney U test was used to compare the parameters between groups. The mean sacral segment 1 (S1) regression time was 390.3 [standard deviation (SD):84.38] [95% confidence interval (CI): 360.13, 420.53] versus 393.23 (SD: 93.01) (95% CI: 363.04, 423.43) min in Group D versus Group LKD respectively ((P = 0.701). The number of episodes of hypotension was significantly higher in Group D (19 patients) compared to Group LKD (nine patients) (P = 0.001). Pre- and postoperative stress markers (24 h) and the incidence of postoperative nausea and shivering were comparable between the two groups (P > 0.05). Tramadol requirement in the postoperative period was significantly less in Group LKD compared to Group D (P = 0.003). The duration of S1 regression was similar between group dexmedetomidine (Group D) and group low-dose ketamine and dexmedetomidine (Group LKD).

A comparative assessment of age-related nicotinamide adenine dinucleotide phosphate-diaphorase positivity in the spinal cord and medulla oblongata of pigeons, rats, and mice.

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase (N-d) positive neurons have been extensively studied across various animals, and N-d neurodegenerative neurites have been detected in some aged animal models. However, detailed knowledge on N-d positivity and aging-related alterations in the spinal cord and medulla oblongata of pigeons is limited. In this study, we investigated N-d positivity and age-related changes in the pigeon's spinal cord and medulla oblongata and compared them to those in rats and mice. Pigeons, had more N-d neurons in the dorsal horn, around the central canal, and in the column of Terni in the thoracic and lumbar segments, with scattered neurons found in the ventral horn of the spinal segments. N-d neurons were also present in the white matter of the spinal cord. Morphometric analysis revealed that the size of N-d soma in the lumbosacral, cervical, and thoracic regions was substantially altered in aged pigeons compared to young birds. Furthermore, the lumbar to sacral segments underwent significant morphological alterations. The main findings of this study were the presence of age-related N-d positive bodies (ANB) in aged pigeons, predominantly in the external cuneate nucleus (CuE) and occasionally in the gracilis and CuEs. ANBs were also identified in the gracile nuclei and spinal cord in the aged rats and mice, whereas in aged rats, ANBs were detected in the CuE spinal nucleus. Immunohistochemistry showed that the age-related alterations occurred in the cell types and neuropeptides in old animals. The results suggest weak inflammatory response and neuronal dysfunction in the spinal cord in aged pigeons. Our results suggested that the ANB could be a potential aging marker for the central nervous system.

The diagnostic accuracy of neuromonitoring for detecting postoperative bowel and bladder dysfunction in spinal oncology surgery: a case series.

Postoperative bowel and bladder dysfunction (BBD) poses a significant risk following surgery of the sacral spinal segments and sacral nerve roots, particularly in neuro-oncology cases. The need for more reliable neuromonitoring techniques to enhance the safety of spine surgery is evident. We conducted a case series comprising 60 procedures involving 56 patients, spanning from September 2022 to January 2024. We assessed the diagnostic accuracy of sacral reflexes (bulbocavernosus and external urethral sphincter reflexes) and compared them with transcranial motor evoked potentials (TCMEP) incorporating anal sphincter (AS) and external urethral sphincter (EUS) recordings, as well as spontaneous electromyography (s-EMG) with AS and EUS recordings. Sacral reflexes demonstrated a specificity of 100% in predicting postoperative BBD, with a sensitivity of 73.33%. While sensitivity slightly decreased to 64.71% at the 1-month follow-up, it remained consistently high overall. TCMEP with AS/EUS recordings did not identify any instances of postoperative BBD, whereas s-EMG with AS/EUS recordings showed a sensitivity of 14.29% and a specificity of 97.14%. Sacral reflex monitoring emerges as a robust adjunct to routine neuromonitoring, offering surgeons valuable predictive insights to potentially mitigate the occurrence of postoperative BBD.

Insertion sites of iliosacral screws on the posterior ilium: Implications for posterior pelvic fixation

ObjectivesLateral compression type II pelvic ring injuries can be treated with fixation through open or percutaneous approaches depending on the injury pattern and available osseous fixation pathways. The start site of iliosacral screws to stabilize these injuries should be on the unstable posterior iliac fragment; however, our understanding of start sites for iliosacral screws has not been developed. The purpose of this study is to provide an analysis of iliosacral screw start sites on the posterior ilium to help guide treatment of pelvic ring injuries. MethodsOne-hundred and seventeen consecutive patients at an academic level I trauma center with pelvic ring injuries who underwent surgical treatment with iliosacral screws were included in the final analysis. The start sites of iliosacral screws with confirmed intraosseous placement on a postoperative computed tomography were mapped on the posterior ilium and analyzed according to the sacral segment and type of iliosacral screw. ResultsOne-hundred and seventeen patients were included in the final analysis. Of the total of 272 iliosacral screw insertion sites analyzed, 145 (53%) were sacroiliac-style screws and 127 (47%) were transsacral screws. The insertion sites for sacroiliac-style screws and transsacral screws at different sacral segment levels can vary but have predictable regions on the posterior ilium relative to reliable osseous landmarks. ConclusionsIliosacral screws start sites on the posterior ilium have reliable regions that can be used to plan posterior fixation of pelvic ring injuries.

Sacral dysmorphism and its influence on hardware choice in sacral fractures: A scoping review

Purpose In the setting of sacral fractures, percutaneous screw fixation is a reliable, safe, and minimally invasive method for managing most stable and unstable fractures. However, significant variations in sacral anatomy due to sacral dysmorphism (SDM) could prevent safe implementation. This scoping review aimed to highlight such a detrimental yet under-reported variable in managing sacral fractures. Methods A scoping review was conducted following the Arksey and O’Malley framework for scoping studies. A comprehensive literature search of four electronic databases was conducted to identify relevant peer-reviewed studies. Data were extracted from eligible articles to summarize, collate, and create a narrative account of the findings. Results Twenty-one articles were included in our review (18 level III, two level II, and one level I). Studies were categorized into three main groups based on the investigated outcomes: prevalence and determinants of SDM, effect of SDM on the surgical corridor, and efficacy of different intra-operative imaging modalities. The prevalence of SDM ranged from 10 to 85%. The presence of SDM decreased the available surgical corridor at S1, with a compensated increase at S2 and S3. Mixed results regarding accuracy and revision rate were identified between different intra-operative imaging techniques. Conclusion SDM represents consistent yet atypical “safe zone,” sizes, and angles that require careful analysis and technique alterations when placing upper and second sacral segment screws. Considering their limited availability, high cost, and mixed results, navigated imaging systems represent a promising technique that requires more rigorous examination of its efficacy before widespread adoption.

Diagnosis and treatment of retrorectal cystic hamartoma: clinical case

Background. Retrorectal tumors are a rare group of tumors that can be benign or malignant in origin; in most cases, they are asymptomatic. They mainly arise in the presacral space, which is limited by Waldeyer’s fascia posteriorly, the rectal fascia proper anteriorly, the ureters and lateral ligaments of the rectum laterally, the levator ani muscles and coccyx inferiorly, and the transition of the pelvic peritoneum between the second and third sacral segments superiorly. Magnetic resonance imaging (MRI) is crucial for diagnosis and surgical planning. Most retrorectal tumors require surgical treatment without preoperative biopsy. Here, we present a case of a retrorectal cystic hamartoma that was treated with surgery.Clinical case. Patient N., 45 years old, presented with suspected pelvic malformation. The patient reported experiencing pain in the sacrum area since May 2023, with no history of trauma. She sought medical help at a local polyclinic, where an ultrasound of the pelvic organs revealed a pelvic mass. The patient was then referred to an oncologist at the Multidisciplinary Clinical Medical Center “Medical City”. Physical examination showed no specific features, except upon rectal examination, where a non-displaced tumor measuring up to 2 cm was palpated along the posterior rectal wall. MRI of the pelvic organs confirmed the presence of a mass behind the lower ampullary rectum. Surgical treatment was subsequently performed, and the diagnosis of teratoma was confirmed through morphological and immunohistochemical studies.Conclusion. Early comprehensive diagnostics and an experienced surgical team are key factors for successful treatment of patients with retrorectal tumors.

Magnetic resonance imaging features and classification of intraspinal echinococcosis

ObjectiveThis study aimed to investigate the magnetic resonance imaging (MRI) features and classification of echinococcosis of the spinal canal. MethodsThe clinical manifestations and MRI findings and classification of 19 patients diagnosed with intraspinal echinococcosis over 10 years (2011–2020) were retrospectively analyzed. ResultsThe mean age of the nine males and 10 females was 39 years (range 28–65 years). Among these, the number of cases with thoracic, lumbar, sacral, thoracolumbar, and lumbosacral, cervical, and lumbar segments was nine (47 %), five (26 %), one (5 %), one (5 %), two (11 %), and one (5 %) cases, respectively. Furthermore, 13 cases (69 %) involved adjacent vertebral bodies, accessories, and surrounding soft tissues. The lesion was confined to the intramedullary, extramedullary subdural, extramedullary epidural, and multiple spaces in one (Type I) (5 %), four (Type II) (21 %), one (Type III) (5 %), and thirteen (69 %) cases, respectively. Moreover, nine cases (47 %) had a history of hydatid disease in the spine or other tissues. The clinical manifestations were chest and lumbosacral pain in 18 cases (95 %) and chest and lumbosacral pain accompanied by lower limb dysfunction in four cases (21 %). The MRI revealed different sizes of T1WI low-signal and T2WI high-signal vesicles with a “grape-like” appearance, with 16 cases (84 %) showing low signals on the edge of the cyst wall. ConclusionIntraspinal echinococcosis is rare, even in endemic areas. However, intraspinal echinococcosis should be considered when there is a history of echinococcosis in other sites or when there are clear MRI characteristics for the disease.

Morphometric analysis of sacral corridor in the upper three sacral segments to prevent neurovascular injury.

Although studies of the sacral corridor dimension have been reported in the European population, little attention has been paid to this issue in the Asian population. The purpose of the study is to estimate the safe dimension of the corridor to avoid neurovascular damage during the fixation of the sacral fracture. The study aimed to examine the cephalocaudal (vertical) and the anteroposterior diameter of the bony passage in the upper three sacral segments. The study further examines the effect of age and sex on corridor dimensions at different sacral levels. Three-dimensionally reconstructed sacra from computed tomography of normal subjects were included in the study. Cephalocaudal and anteroposterior diameters were measured in coronal and axial sections using Geomagic Freeform Plus software. Anteroposterior diameter of the sacral corridor at the first, second, and third sacral segments are significantly higher in males (P=0.013, 0.0011, and <0.0001, respectively). The length of the sacrum also revealed sexual dimorphism (P<0.00016). The anteroposterior diameter of the second sacral segment (ap-S2c) correlated moderately with the first sacral anteroposterior diameter (ap-S1c) (R=0.519, P<0.001). The ap-S2c exhibited a moderate correlation to the third sacral segment (ap-S3c) (R=0.677, P<0.001). The sacral corridor at the level of S1 has the largest cephalocaudal (18.25 mm) and anteroposterior diameter (17.11 mm). Placement of the screw in the first sacral corridor may avoid damage to the neurovascular bundle during the fixation of the sacral fracture.

Long-term postoperative outcomes of spinal cellular schwannoma: study of 93 consecutive cases

BACKGROUND CONTEXTCellular schwannoma (CS) is a rare tumor that accounts for 2.8%–5.2% of all benign schwannomas. There is a dearth of up-to-date information on spinal CS in the literature. PURPOSEThe aims of this study were to identify the proportion of CS cases amongst spinal benign schwannoma, describe the clinical features of spinal CS, and identify prognostic factors for local recurrence by analyzing data from 93 consecutive CS cases. STUDY DESIGNRetrospective review. PATIENT SAMPLEWe analyzed 93 PSGCT screened from 1,706 patients with spine CS who were treated at our institute between 2008 and 2021. OUTCOME MEASURESDemographic, radiographic, operative and postoperative data were recorded and analyzed. METHODSWe compared the clinical features of spinal CS from the cervical, thoracic, lumbar and sacral segments. Prognostic factors for local recurrence-free survival (RFS) were identified by the Kaplan-Meier method. Factors with p≤.05 in univariate analysis were subjected to multivariate analysis by Cox regression analysis. RESULTSThe proportion of spinal CS in all benign schwannomas was 6.7%. The mean and median follow-up times for the 93 patients in this study were 92.2 and 91.0 months respectively (range 36–182 months). Local recurrence was detected in 11 cases, giving an overall recurrence rate of 11.7%, with one patient death. Statistical analysis revealed that tumor size ≥5 cm, intralesional resection, and Ki-67 ≥5% were independent negative prognostic factors for RFS in spinal CS. CONCLUSIONSWhenever possible, en bloc resection is recommended for spinal CS. Long-term follow-up should be carried out for patients with tumor size ≥5 cm and postoperative pathological Ki-67 ≥5%.

Techniques for restoring optimal spinal biomechanics to alleviate symptoms in Bertolotti syndrome: illustrative case.

Lumbosacral transitional vertebrae (LSTVs) are congenital anomalies that occur in the spinal segments of L5-S1. These vertebrae result from sacralization of the lowermost lumbar segment or lumbarization of the uppermost sacral segment. When the lowest lumbar vertebra fuses or forms a false joint with the sacrum (pseudoarticulation), it can cause pain and manifest clinically as Bertolotti syndrome. A 36-year-old female presented with severe right-sided low-back pain. Computed tomography was unremarkable except for a right-sided Castellvi type IIA LSTV. The pain proved refractory to physical therapy and lumbar epidural spinal injections, but targeted steroid and bupivacaine injection of the pseudoarticulation led to 2 weeks of complete pain relief. She subsequently underwent minimally invasive resection of the pseudoarticulation, with immediate improvement in her low-back pain. The patient continued to be pain free at the 3-year follow-up. LSTVs alter the biomechanics of the lumbosacral spine, which can lead to medically refractory mechanical pain requiring surgical intervention. Select patients with Bertolotti syndrome can benefit from operative management, including resection, fusion, or decompression of the pathologic joint.

The influence of lumbosacral transitional vertebrae on lumbar lordosis and the angle of pelvic incidence.

Pelvic incidence and lumbar lordosis have only normative values for spines comprising five lumbar and five sacral vertebrae. However, it is unclear how pelvic incidence and lumbar lordosis are affected by the common segmentation anomalies at the lumbo-sacral border leading to lumbosacral transitional vertebrae, including lumbarisations and sacralisations. In lumbosacral transitional vertebrae it is not trivial to identify the correct vertebral endplates to measure pelvic incidence and lumbar lordosis because ontogenetically the first sacral vertebra represents the first non-mobile sacral segment in lumbarisations, but the second segment in sacralisations. We therefore assessed pelvic incidence and lumbar lordosis with respect to both of these vertebral endplates. The type of segmentation anomaly was differentiated using spinal counts, spatial relationship with the iliac crest and morphological features. We found significant differences in pelvic incidence and lumbar lordosis between lumbarisations, sacralisations and the control group. The pelvic incidence in the sacralised group was mostly below the range of the lubarisation group and the control group when measured the traditional way at the first non-mobile segment (30.2°). However, the ranges of the sacralisation and lubarisation groups were completely encompassed by the control group when measured at the ontogenetically true first sacral vertebra. The mean pelvic incidence of the sacraliation group thus increased from 30.2° to 58.6°, and the mean pelvic incidence of the total sample increased from 45.6° to 51.2°, making it statistically indistinguishable from the control sample, whose pelvic incidence was 50.2°. Our results demonstrate that it is crucial to differentiate sacralisations from lumbarisation in order to assess the reference vertebra for pelvic incidence measurement. Due to their significant impact on spino-pelvic parameters, lumbosacral transitional vertebrae should be evaluated separately when examining pelvic incidence and lumbar lordosis.

Deep learning-based k-space-to-image reconstruction and super resolution for diffusion-weighted imaging in whole-spine MRI

PurposeTo assess the feasibility of deep learning (DL)-based k-space-to-image reconstruction and super resolution for whole-spine diffusion-weighted imaging (DWI). MethodThis retrospective study included 97 consecutive patients with hematologic and/or oncologic diseases who underwent DL-processed whole-spine MRI from July 2022 to March 2023. For each patient, conventional (CONV) axial single-shot echo-planar DWI (b = 50, 800 s/mm2) was performed, followed by DL reconstruction and super resolution processing. The presence of malignant lesions and qualitative (overall image quality and diagnostic confidence) and quantitative (nonuniformity [NU], lesion contrast, signal-to-noise ratio [SNR], contrast-to-noise ratio [CNR], and ADC values) parameters were assessed for DL and CONV DWI. ResultsUltimately, 67 patients (mean age, 63.0 years; 35 females) were analyzed. The proportions of vertebrae with malignant lesions for both protocols were not significantly different (P: [0.55–0.99]). The overall image quality and diagnostic confidence scores were higher for DL DWI (all P ≤ 0.002) than CONV DWI. The NU, lesion contrast, SNR, and CNR of each vertebral segment (P ≤ 0.04) but not the NU of the sacral segment (P = 0.51) showed significant differences between protocols. For DL DWI, the NU was lower, and lesion contrast, SNR, and CNR were higher than those of CONV DWI (median values of all segments; 19.8 vs. 22.2, 5.4 vs. 4.3, 7.3 vs. 5.5, and 0.8 vs. 0.7). Mean ADC values of the lesions did not significantly differ between the protocols (P: [0.16–0.89]). ConclusionsDL reconstruction can improve the image quality of whole-spine diffusion imaging.

Operative outcomes and fracture patterns in dysmorphic sacrums

IntroductionSacral dysmorphism has been previously reported to occur in 30 % to 40 % of adult patients. It has been described by 6 widely accepted parameters on outlet x-ray views of the pelvis: steep alar slope, retained S1-S2 disk, presence of mamillary bodies, sacralized L5, tongue in groove SI joint, and non-round neural foramina. Studies have focused on the importance of identifying dysmorphism for safe treatment of fractures in pelvises with dysmorphic upper sacral segments. Less is known regarding whether dysmorphism may be protective against trauma. To our knowledge no studies have focused on how dysmorphic sacrums fracture compared to non-dysmorphic (ND) sacrums, and whether operative rates are different. AimsTo assess the rate of operative fixation of sacral fractures between pelvises with dysmorphic and ND sacrums, as well as whether a difference exists in fracture morphology between groups. Design/MethodsThis is a retrospective cohort study out of a single level 1 trauma center. Study participants consisted of those sustaining a pelvic ring injury who were 18 years or older in which orthopaedics was consulted, had CT imaging available, and did not have isolated acetabulum fractures. 355 subjects were included of 671 reviewed pelvic ring injuries. Sacrums were deemed dysmorphic if they met at least one of the six dysmorphic features, and it was determined whether they underwent operative intervention. Fracture classifications and patterning were identified on CT imaging. P values were set <0.05. ResultsWe found that 44 % of inclusions had a dysmorphic sacrum with the most common feature to be a steep alar slope (68 %). 17.17 % of subjects with a ND sacrum underwent treatment versus 16.56 % for dysmorphic sacrums. No statistical difference regarding operative fixation rates was uncovered (p = .879). However, we found a difference in fracture patterns regarding ipsilateral posterior SI joint widening (p = 0.020). ConclusionOur study suggests that sacral dysmorphism is not protective against operative fixation based on no difference in operative rates between groups. However, our data supports that pelvises with dysmorphic sacrums may fracture differently based on the difference observed regarding other pelvic ring injuries.

PELVİS TİPLERİNİN TRANS-SAKRAL VİDA KORİDOR ÇAPINA ETKİSİNİN DEĞERLENDİRİLMESİ (BİLGİSAYARLI TOMOGRAFİ VERİLERİ KULLANILARAK YAPILAN RETROSPEKTİF ANALİZ.)

Aims: The aim of this study was to investigate the effect of pelvis type on the trans-sacral(TS) screw corridor diameter.&#x0D; Methods: Pelvis computed tomography (CT) scans between 2017 and 2020 were retrospectively reviewed. Age, gender, height, weight and body mass index (BMI) of the patients were determined during the CT examination. Pelvic CT scans were examined using the imaging system's multi-plane reconstruction (MPR) mode, and the TS screw corridor was measured for both the upper and second sacral segments. In addition, pelvic incidence (PI), sacral tilt (SS), and pelvic tilt (PT) values were measured. Pelvis typing was performed using the large transverse diameter, anteroposterior diameter, interspinous, intertuberocytosis, transverse outlet diameter, sagittal mid-pelvic diameter, and sagittal outlet values.&#x0D; Results: 81(38%) male and 132(62%) female patients were included in the study. Gynecoid pelvis type was more common in females and android pelvis in males (p &lt; 0.001). The largest diameters in the TS screw corridor at the S1 level belonged to the anthropoid pelvis type. However, in the TS corridor at the S2 level, there was a significant difference between the pelvis-type groups in the mean values of AP and CC (p &lt; 0.001). The effect of gender difference on the TS screw corridor width at the S1 and S2 levels was significant. An adequate corridor width for the TS screw corridor was detected in 50.8% of females and 67.9% of males at the S1 level, while in 21.2% of females and 70.4% of males at the S2 level.&#x0D; Conclusions: There is a significant difference in the dimensions of the trans-sacral screw corridor according to the pelvis type and gender, with the largest diameter observed in the anthropoid pelvis type and males. In critical situations, especially in males and individuals with android-anthropoid pelvis, the trans-sacral screw option should be considered primarily not only for the S1 trans-sacral corridor but also for the S2 trans-sacral corridor in pelvic posterior ring injuries

Stereotactic Body Radiotherapy (SBRT) for Sacral Metastases: Deviation from Recommended Target Volume Delineation Predicts Higher Risk of Local Failure

A international consensus recommendation was published to guide target volume delineation specific to sacral stereotactic body radiotherapy (SBRT). We report outcomes after sacrum SBRT, focusing on the impact of contouring deviation on local failure (LF) risk, with an aim to validate this guideline. All patients who underwent SBRT to any level between S1 and S5 from 2010 to 2021 were identified from a prospectively maintained institutional database. The primary outcome was magnetic resonance-based LF. Secondary outcomes included vertebral compression fracture (VCF) and overall survival (OS). Cumulative LF and VCF rates were calculated per segment using the competing risk analysis method. Kaplan Meier analysis was used to estimate OS per patient. Cox proportional hazards model was used to assess predictive factors of LF, VCF, and OS. A total of 215 treated sacral segments in 112 patients were retrospectively reviewed. The median follow-up was 13 months (range, 0.4-116.9). The median age was 64 years (range, 18-86), and 56% were male. Most patients (52%) had treatment to a single segment. The median clinical target volume (CTV) was 129.2 cc (range, 5.8-753.5). Most segments were treated with 30 Gy/4 fractions (51%), 24 Gy/2 fractions (31%), or 30 Gy/5 fractions (10%). Thirty-one percent of segments were of radioresistant histology (gastrointestinal, kidney, melanoma, sarcoma, or thyroid primary), and 51% had extraosseous disease. Sixteen percent of segments were under-contoured per consensus guidelines, with incomplete coverage of the involved sector (71%), omission of the adjacent uninvolved sector (17%), or both (11%) as the causes for deviation. The cumulative incidence of LF was 18.4% (95% CI 13.5-24.0) at 12-months and 23.1% (95% CI 17.6-29.0) at 24-months. On multivariate analysis (MVA), under-contouring (HR 2.4, 95% CI 1.3-4.7, p = 0.008), radioresistant histology (HR 2.4, 95% CI 1,4-4.1, p = 0.001), and extraosseous extension (HR 2.5, 95% CI 1.3-4.7, p = 0.005) were predictors of increased risk of LF. The LF rates at 12/24-months were 15.1%/18.8% for segments contoured per guideline versus 31.4%/40.0% for those under-contoured. The cumulative incidence of VCF was 7.1% (95% CI 4.1-11.1) at 12-months and 12.3% (95% CI 8.2-17.2) at 24-months. On MVA, female gender was the only risk factor for VCF (HR 2.3, 95% CI 1.1-5.2, p = 0.04). The median OS was 29.5 months (95% CI 17.5-59.2). On MVA, primary kidney (HR 4.7, 95% CI 1.7-12.5, p = 0.002) or lung histology (HR 3.4, 95% CI 1.3-8.5, p = 0.010), the presence of liver (HR 2.8, 95% CI 1.2-6.4, p = 0.016) or lung (HR 2.5, 95% CI 1.3-5.1, p = 0.008) metastases, ECOG performance status 2 or 3 (HR 3.3, 95% CI 1.2-8.2, p = 0.013), and the presence of sensory or motor deficit (HR 2.6, 95% CI 1.2-5.4, p = 0.012) were prognostic for worse OS. Sacral SBRT is associated with high rates of efficacy and an acceptable VCF risk. Adherence to target volume delineation consensus guidelines reduces the risk of LF.

STEREOTACTIC BODY RADIOTHERAPY (SBRT) FOR SACRAL METASTASES: DEVIATION FROM RECOMMENDED TARGET VOLUME DELINEATION PREDICTS HIGHER RISK OF LOCAL FAILURE

Abstract Report outcomes after sacrum SBRT, focusing on the impact of contouring deviation on local failure (LF) risk, with an aim to validate the contouring consensus guidelines. METHODS/MATERIALS: Patients who underwent sacral SBRT from 2010- 2021 were identified from a prospectively maintained institutional database. Primary outcomes were magnetic resonance-based LF and vertebral compression fracture (VCF). RESULTS: A total of 215 treated sacral segments in 112 patients were reviewed. Most segments were treated with 30 Gy/4 fractions (51%), 24 Gy/2 fractions (31%), or 30 Gy/5 fractions (10%). Thirty-one percent of segments were of radioresistant histology (gastrointestinal, kidney, melanoma, sarcoma, or thyroid primary), and 51% had extraosseous disease. Sixteen percent of segments were under-contoured per consensus guidelines. The cumulative incidence of LF was 18.4% (95% CI 13.5-24.0) at 12-months and 23.1% (95% CI 17.6-29.0) at 24-months. On multivariate analysis (MVA), under- contouring (HR 2.4, 95% CI 1.3-4.7, p=0.008), radioresistant histology (HR 2.4, 95% CI 1,4-4.1, p=0.001), and extraosseous extension (HR 2.5, 95% CI 1.3-4.7, p=0.005) were predictors of increased risk of LF. The LF rates at 12/24-months were 15.1%/18.8% for segments contoured per guideline versus 31.4%/40.0% for those under-contoured. The cumulative incidence of VCF was 7.1% (95% CI 4.1-11.1) at 12-months and 12.3% (95% CI 8.2-17.2) at 24-months. On MVA, female gender predicted increased VCF risk (HR 2.3, 95% CI 1.1-5.2, p=0.04). CONCLUSIONS: Sacral SBRT is associated with high rates of efficacy and an acceptable VCF risk. Adherence to target volume delineation consensus guidelines reduces the risk of LF.

Immunohistochemical characteristics of the gray matter of the human spinal cord in the late prenatal period

The study is dedicated to the relevant problem of studying the patterns of age-related (prenatal) restructuring in the brain and spinal cord and provides opportunities for predicting and correcting the occurrence of congenital defects. The aim of the research was to establish the nature of immunohistochemical marker expression in the gray matter structures of the human spinal cord during the late prenatal period. The material for the study consisted of spinal cord preparations from 27 human fetuses at gestational age 35-40 weeks. The following methods were used during the research: anatomical, general histological, special histological, immunohistochemical, morphometric, and statistical analysis of the obtained data. It was found that at 35-36 weeks of the gestational period, the proliferation of neural stem cells (NSCs) occurs more intensively in the ventral neuroepithelium of spinal cord segments compared to the dorsal neuroepithelium. In the ventral neuroepithelium, there are 5-6 mitotic or post-mitotic NSCs, while in the dorsal part, there are only 2-3 cells. In fetuses at 39-40 weeks, the proliferative activity of neural stem cells in the dorsal neuroepithelium is higher in cervical and lumbar segments, where Ki-67 expression is detected in 6 % of cells (reactive in 7-8 cells), and in thoracic and sacral segments, it is 4 % (reactive in 3-4 cells). In contrast to the dorsal neuroepithelium, in the ventral part of the neuroepithelium of the segments, the proliferative activity of neural stem cells is slightly less intense. In cervical and lumbar segments, Ki-67 expression occurred in 4 % of cells (reactive in 3-4 cells), and in thoracic and sacral segments, it was 2 % (reactive in 1-2 cells). At 35-36 weeks of gestation, high vimentin expression was observed around the neuroepithelium, at the base of the posterior horns, and along the posterior median septum. Vimentin expression in the mantle layer was relatively weak and persisted along blood vessels and in the area of spinal cord root formation. Before birth, relatively weak vimentin expression was detected in the remnants of radial glia surrounding the neuroepithelial layer. Vimentin expression was absent in the neuroepithelium proper, but focal vimentin expression was observed around blood vessels. The absence of vimentin expression in the neuroepithelium indicates the disappearance of radial cells. At 35-40 weeks of the gestational period, relatively strong synaptophysin expression was observed in the mantle layer of spinal cord segments, indicating the intensity of neuronal connectivity establishment and myelination of nerve fibers. These processes continue after birth. Synaptophysin expression was absent in the neuroepithelium proper.

Incidence of and Risk Factors for Screw Loosening after Iliosacral Screw Fixation for Posterior Pelvic Ring Injury.

Screw loosening is a common complication of iliosacral screw fixation, with subsequent loss of stability and fracture re-displacement. This study aimed to investigate the incidence of and risk factors for screw loosening after iliosacral screw fixation for posterior pelvic ring injury. A total of 135 patients with posterior pelvic ring injuries who were treated with iliosacral screw fixation in our department between July 2015 and April 2021 were selected for this retrospective analysis. The possible risk factors for screw loosening were investigated using univariate and multivariate logistic regression analyses of patient demographics and trauma-related and iatrogenic variables, including age, sex, body mass index, Osteoporosis Self-Assessment Tool for Asians (OSTA) index, mechanism of injury, Young-Burgess classification, site of injury, type of injury, type of screw, mode of fixation, numbers of guidewire adjustments, accuracy of screw position, and quality of fracture reduction. The incidence of screw loosening was 15.6% (n = 21). The mean duration for screw loosening was 3.2 ± 1.5 months after operation. Univariate analysis results showed that the Young-Burgess classification, type of injury, site of injury, type of screw, mode of fixation, and OSTA index might be related to screw loosening (p < 0.05). According to the multivariate logistic regression, vertical shear injuries (Odds ratios [OR] 9.80, 95% Confidence intervals [CI] [1.96-73.28], p = 0.008), type of injury (OR 0.25, 95% CI [0.13-0.79], p = 0.027), common screws (OR 6.94, 95% CI [1.53-31.40], p = 0.012), screws insertion only at the level of the first sacral segment (S1) (OR 8.79, 95% CI [1.18-65.46], p = 0.034), injury site located in the medial sacral foramina (OR 6.28, 95% CI [1.16-34.06], p = 0.033), and lower OSTA index [OR 0.41, 95% CI [0.24-0.71], p = 0.001] were significantly related to screw loosening. Vertical shear injuries, sacral fractures, injury site located in the medial sacral foramina, and lower OSTA index are significantly associated with the postoperative occurrence of screw loosening. Transiliac-transsacral screw fixation and screws insertion both at the level of the S1 and second sacral segment can prevent screw loosening.