Ultrasound-Guided Sacral Erector Spinae Plane Block: A Feasible Option for Pain Management During Magnetic Resonance Imaging: A Case Report.

Inability to remain motionless owing to pain during magnetic resonance imaging (MRI) may increase the need for sedation and analgesia. Here, we present a case where ultrasound-guided sacral erector spinae plane block (ESPB) was used successfully for pain management during an MRI in a patient suffering from severe sacral pain. Sacral ESPB was performed with a total of 30 mL of 0.25% bupivacaine at the level of the intermediate sacral crest. The patient achieved sensory block in the L5-S4 dermatomes without motor block, resulting in complete pain relief. This case report highlights the feasibility of ultrasound-guided sacral ESPB as a potential pain management technique.

Preoperative and follow-up variations of psoas major muscle are related to S1 screw loosening in patients with degenerative lumbar spinal stenosis.

BACKGROUND: It was reported the paraspinal muscle played an important role in spinal stability. The preoperative paraspinal muscle was related to S1 screw loosening. But the relationship between preoperative and postoperative change of psoas major muscle (PS) and S1 pedicle screw loosening in degenerative lumbar spinal stenosis (DLSS) patients has not been reported. This study investigated the effects of preoperative and follow-up variations in the psoas major muscle (PS) on the first sacral vertebra (S1) screw loosening in patients with DLSS. METHODS: 212 patients with DLSS who underwent lumbar surgery were included. The patients were divided into the S1 screw loosening group and the S1 screw non-loosening group. Muscle parameters were measured preoperatively and at last follow-up magnetic resonance imaging. A logistic regression analysis was performed to investigate the risk factors for S1 screw loosening. RESULTS: The S1 screw loosening rate was 36.32% (77/212). The relative total cross-sectional areas and relative functional cross-sectional areas (rfCSAs) of the PS at L2-S1 were significantly higher after surgery. The increased rfCSA values of the PS at L3-S1 in the S1 screw non-loosening group were significantly higher than those in the S1 screw loosening group. The regression analysis showed male, lower CT value of L1 and longer segment fusion were independent risk factors for S1 screw loosening, and postoperative hypertrophy of the PS was a protective factor for S1 screw loosening. CONCLUSIONS: Compared to the preoperative muscle, the PS size increased and fatty infiltration decreased after surgery from L2-3 to L5-S1 in patients with DLSS after short-segment lumbar fusion surgery. Postoperative hypertrophy of the PS might be considered as a protective factor for S1 screw loosening. MRI morphometric parameters and postoperative selected exercise of PS for DLSS patients after posterior lumbar fusion surgery might contribute to improvement of surgical outcome.

Multidisciplinary surgical considerations for en bloc resection of sacral chordoma: review of recent advances and a contemporary single-center series.

OBJECTIVE: Contemporary management of sacral chordomas requires maximizing the potential for recurrence-free and overall survival while minimizing treatment morbidity. En bloc resection can be performed at various levels of the sacrum, with tumor location and volume ultimately dictating the necessary extent of resection and subsequent tissue reconstruction. Because tumor resection involving the upper sacrum may be quite destabilizing, other pertinent considerations relate to instrumentation and subsequent tissue reconstruction. The primary aim of this study was to survey the surgical approaches used for managing primary sacral chordoma according to location of lumbosacral spine involvement, including a narrative review of the literature and examination of the authors' institutional case series. METHODS: The authors performed a narrative review of pertinent literature regarding reconstruction and complication avoidance techniques following en bloc resection of primary sacral tumors, supplemented by a contemporary series of 11 cases from their cohort. Relevant surgical anatomy, advances in instrumentation and reconstruction techniques, intraoperative imaging and navigation, soft-tissue reconstruction, and wound complication avoidance are also discussed. RESULTS: The review of the literature identified several surgical approaches used for management of primary sacral chordoma localized to low sacral levels (mid-S2 and below), high sacral levels (involving upper S2 and above), and high sacral levels with lumbar involvement. In the contemporary case series, the majority of cases (8/11) presented as low sacral tumors that did not require instrumentation. A minority required more extensive instrumentation and reconstruction, with 2 tumors involving upper S2 and/or S1 levels and 1 tumor extending into the lower lumbar spine. En bloc resection was successfully achieved in 10 of 11 cases, with a colostomy required in 2 cases due to rectal involvement. All 11 cases underwent musculocutaneous flap wound closure by plastic surgery, with none experiencing wound complications requiring revision. CONCLUSIONS: The modern management of sacral chordoma involves a multidisciplinary team of surgeons and intraoperative technologies to minimize surgical morbidity while optimizing oncological outcomes through en bloc resection. Most cases present with lower sacral tumors not requiring instrumentation, but stabilizing instrumentation and lumbosacral reconstruction are often required in upper sacral and lumbosacral cases. Among efforts to minimize wound-related complications, musculocutaneous flap closure stands out as an evidence-based measure that may mitigate risk.

Characterization of sacral chordoma and differential diagnosis from other sacral malignancy using [18F]FDG PET/CT.

2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET)/computed tomography (CT) is known to be a helpful imaging modality for sacral chordoma, but its detailed characteristics have not been fully described. The purpose of our study was to identify the [18F]FDG PET/CT imaging characteristics of sacral chordoma and compare them with other sacral malignancy. This retrospective study included patients who underwent [18F]FDG PET/CT because of a mass involving the sacrum. Investigated visual findings included visual score and distribution, and semiquantitative parameters measured included standardized uptake values (SUVmax, SUVpeak, SUVmean), tumor-to-liver ratio (TLR), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor size. Comparison studies and receiver operating characteristics (ROC) curve analysis were performed to differentiate between sacral chordoma and other sacral malignancy. Ten patients with sacral chordoma were finally included (M:F = 6:4, median age = 67 yr). On [18F]FDG PET/CT, sacral chordomas presented as a mass with minimal-moderate uptake with a usually heterogenous distribution. Compared with 12 patients with other sacral malignancies (M:F = 4:8, median age 42 yr), sacral chordoma showed a significantly lower TLR (median value 2.1 vs 6.3, P = .021). In ROC curve analysis, TLR showed the largest area under the curve (AUC) of 0.79 (cutoff ≤ 4.0; sensitivity 100.0%, specificity 58.3%; P = .004), and SUVmax showed the second largest AUC of 0.73 (cutoff ≤ 6.9; sensitivity 80.0%, specificity 66.7%; P = .034). [18F]FDG PET/CT of sacral chordoma showed minimal-moderate uptake. The TLR of [18F]FDG PET/CT was significantly lower than that of other sacral malignancy and was the most useful parameter for differentiating sacral chordoma, with the largest AUC. SUVmax could be another helpful semiquantitative parameter.

L1 slope: an overlooked spinal parameter.

OBJECTIVE: Lumbar lordosis can be divided into two parts by a horizontal line, creating the L1 slope and the sacral slope. Despite being a major spinopelvic parameter, the L1slope (L1S) is rarely reported. However, there is some evidence that L1S is a relatively constant parameter. This study aimed to analyze the L1 slope and its relationships with other spinopelvic parameters. METHODS: Standing lateral lumbosacral x-ray radiographies of 76 patients with low back pain and CT scans of 116 asymptomatic subjects were evaluated for spinal and spinopelvic parameters including L1 slope (L1S). The x-ray and CT groups were divided into subgroups according to mean sacral slope (SS) or pelvic incidence (PI) values. The mean values of the spinopelvic parameters and the correlations between them were investigated and compared. RESULTS: L1S was 19.70 and 18.15 in low SS and high SS subgroups of x-ray respectively. L1S was 7.95 and 9.36 in low and high PI subgroups of CT, respectively, and the differences were insignificant statistically. L1S was the only spinal parameter that did not change as SS or PI increased in standing and supine positions. L1S was correlated with lumbar lordosis (LL) proximal lumbar lordosis (PLL) and distal lumbar lordosis (DLL) in both x-ray and CT groups. L1S was also the strongest correlated parameter with pelvic incidence lumbar lordosis mismatch (PI-LL) mismatch in supine position. CONCLUSIONS: L1S is a relatively constant parameter and is around 16°-18° and 8°-9° in the standing and supine positions, respectively. It was significantly correlated with LL, PLL, DLL, and PI-LL. In the standing position it was nearly equal to PLL while this equality was present in low PI subgroups of CT. There is strong evidence that L1S is significantly correlated with health-related quality of life scores.

The influence of pelvic tilt on sacral insufficiency fracture occurrence: Insights into the prevalence of high pelvic tilt among patients affected.

INTRODUCTION: Fragility fractures without significant trauma of the pelvic ring in older patients have an increasing incidence due to demographic change. Influencing factors other than osteoporotic bone quality that lead to an insufficiency fracture are not yet known. However, it is suspected that the pelvic tilt (PT) has an effect on the development of such an insufficiency fracture. This study explores the influence of the PTs in patients with insufficiency fractures of the posterior pelvic ring. MATERIALS AND METHODS: A total of 49 geriatric patients with fragility fractures of the pelvic ring were treated at a university hospital level-1 trauma center during a period between February and December 2023, and their fractures were classified according to the FFP classification of Rommens and Hofmann. Complete sets of computer tomography (CT) and radiological images were available to determine the PT angle of the patients. RESULTS: 34 FFP type 2 and 15 FFP type 3 classified patients were included in the study. Significant difference was seen in the pelvic tilt (PT) angle between the patient group with insufficiency fractures (n= 49; mean age: 78.02 ± 11.80) and the control group with lumbago patients (n= 53; mean age: 69.23 ± 11.23). The PT was significantly higher in the patients with insufficiency fractures (25.74° ± 4.76; p⁎⁎⁎⁎ ≤ 0.0001). CONCLUSIONS: The study demonstrates a significant extension of the PT angle of individuals with insufficiency fractures when compared to those with lumbago. The result suggests a potential association between pelvic tilt and fracture susceptibility. TRIAL REGISTRATION: A retrospective study about the influence of sagittal balance of the spine on insufficiency fractures of the posterior pelvic ring measured by the "pelvic tilt angle", DRKS00032120. Registered 20th June 2023 - Prospectively registered. Trial registration number DRKS00032120.

Lumbar lordosis and sacral slope do not differ in two types of postoperative lumbar disc re-herniation: a cross-sectional observational study.

BACKGROUND: To identify the differences of lumbar lordosis (LL) and sacral slope (SS) angles between two types of postoperative lumbar disc re-herniation, including the recurrence of same level and adjacent segment herniation (ASH). METHODS: We searched the medical records of lumbar disc herniation (LDH) patients with re-herniation with complete imaging data (n = 58) from January 1, 2013 to December 30, 2020 in our hospital. After matching for age and sex, 58 patients with LDH without re-herniation from the same period operated by the same treatment group in our hospital were served as a control group. Re-herniation patients were divided into two groups, same-level recurrent lumbar disc herniation group (rLDHG) and adjacent segment herniation group with or without recurrence (ASHG). The preoperative, postoperative and one month after operation LL and SS were measured on standing radiographs and compared with the control group by using t-test, ANOVA, and rank-sum test. Next, we calculated the odds ratios (ORs) by unconditional logistic regression, progressively adjusted for other confounding factors. RESULTS: Compared with the control group, the postoperative LL and SS were significantly lower in LDH patients with re-herniation. However, there were no differences in LL and SS between ASHG and rLDHG at any stage. After progressive adjustment for confounding factors, no matter what stage is, LL and SS remained unassociated with the two types of re-herniation. CONCLUSIONS: Low postoperative LL and SS angles are associated with degeneration of the remaining disc. Low LL and SS may be independent risk factors for re-herniation but cannot determine type of recurrence (same or adjacent disc level).

The Influence of Radiographic Parameter on the S2 Alar-Iliac Screw Virtual Trajectory in Degenerative Lumbar Scoliosis Patients: A Computed Tomography Study.

OBJECTIVE: S2 alar-iliac (S2AI) screw had been widely used in the pelvic fusion for degenerative lumbar scoliosis (DLS) patients. However, whether S2AI screw trajectory was influenced by sagittal profile in DLS patients had not been comprehensively investigated. The objective of this study was to evaluate the associations between the optimal S2 alar-iliac (S2AI) screw trajectory and sagittal spinopelvic parameters in DLS patients. METHODS: Computed tomography (CT) scans of pelvis were performed in 47 DLS patients for three-dimensional reconstruction of S2AI screw trajectory from September 2019 to November 2021. Five S2AI screw trajectory parameters were measured in CT reconstruction images, including: 1) angle in the transverse plane (Tsv angle); 2) angle in the sagittal plane (Sag angle); 3) maximal screw length; 4) screw width; and 5) skin distance. The lumbar Cobb angle, lumbar apical vertebral translation (AVT); global kyphosis (GK); thoracic kyphosis (TK); lumbar lordosis (LL); sagittal vertical axis (SVA); sacral slope (SS); pelvic tilt (PT); and pelvic incidence (PI) were measured in standing X-ray films of the whole spine and pelvis. RESULTS: Both Tsv angle and Sag angle had significant positive associations with SS (p < 0.05) but negative associations with both PT (p < 0.05) and LL (p < 0.05) in all cases. Patients with SS less than 15° had both smaller Tsv angle and Sag angle than those with SS equal to or more than 15° (p < 0.05). The decreased LL would lead to the backward rotation of the pelvis, resulting in a more cephalic and less divergent trajectory of S2AI screw in DLS patients. CONCLUSIONS: For DLS patients with lumbar kyphosis, spine surgeons should avoid both excessive Tsv and Sag angles for S2AI screw insertion, especially when using free-hand technique.

Landet: an efficient physics-informed deep learning approach for automatic detection of anatomical landmarks and measurement of spinopelvic alignment.

PURPOSE: An efficient physics-informed deep learning approach for extracting spinopelvic measures from X-ray images is introduced and its performance is evaluated against manual annotations. METHODS: Two datasets, comprising a total of 1470 images, were collected to evaluate the model's performance. We propose a novel method of detecting landmarks as objects, incorporating their relationships as constraints (LanDet). Using this approach, we trained our deep learning model to extract five spine and pelvis measures: Sacrum Slope (SS), Pelvic Tilt (PT), Pelvic Incidence (PI), Lumbar Lordosis (LL), and Sagittal Vertical Axis (SVA). The results were compared to manually labelled test dataset (GT) as well as measures annotated separately by three surgeons. RESULTS: The LanDet model was evaluated on the two datasets separately and on an extended dataset combining both. The final accuracy for each measure is reported in terms of Mean Absolute Error (MAE), Standard Deviation (SD), and R Pearson correlation coefficient as follows: [ S S ∘ : 3.7 ( 2.7 ) , R = 0.89 ] , [ P T ∘ : 1.3 ( 1.1 ) , R = 0.98 ] , [ P I ∘ : 4.2 ( 3.1 ) , R = 0.93 ] , [ L L ∘ : 5.1 ( 6.4 ) , R = 0.83 ] , [ S V A ( m m ) : 2.1 ( 1.9 ) , R = 0.96 ] . To assess model reliability and compare it against surgeons, the intraclass correlation coefficient (ICC) metric is used. The model demonstrated better consistency with surgeons with all values over 0.88 compared to what was previously reported in the literature. CONCLUSION: The LanDet model exhibits competitive performance compared to existing literature. The effectiveness of the physics-informed constraint method, utilized in our landmark detection as object algorithm, is highlighted. Furthermore, we addressed the limitations of heatmap-based methods for anatomical landmark detection and tackled issues related to mis-identifying of similar or adjacent landmarks instead of intended landmark using this novel approach.

[Prolonged spinal and sacral neurostimulation in children with pelvic organ dysfunction: preliminary analysis]. / Dlitel'naya spinal'naya i sakral'naya neirostimulyatsiya u detei pri narusheniyakh funktsii tazovykh organov: predvaritel'nyi analiz.

OBJECTIVE: To evaluate the clinical efficacy of long-term spinal and sacral programmable neurostimulation for pelvic organ dysfunction in patients with myelodysplasia and chronic dysfunction of the bladder and rectum. MATERIAL AND METHODS: A retrospective study included 32 children aged 1-17 years (mean 10.7) with myelodysplasia, pelvic organ dysfunction and ineffective therapy including botulinum therapy and exclusion of tethered spinal cord syndrome. All children underwent comprehensive urodynamic examination with analysis of bladder and residual urine volume, mean flow rate, intravesical pressure and total urine volume, as well as electromyographic examination. Examination was carried out before surgery, after 6, 12 and 36 months. We applied urinary diary, NBSS questionnaire and urodynamic examination data. All patients underwent neurological examinations (neurological status, magnetic resonance imaging of the spinal cord, computed tomography and radiography of the spine, electroneuromyography). The study was conducted at the neurosurgical department of the Republican Children's Clinical Hospital in Ufa between 2014 and 2022. There were 32 implantations of epidural neurostimulators for pelvic organ dysfunctions. RESULTS: Patients used epidural spinal and sacral stimulation up to 6 times a day for 10-15 min turning on the pulse generator. This method significantly increased urinary volume, decreased episodes of urinary leakage and fecal incontinence, residual volume after urination and number of periodic catheterizations compared to baseline data. Sixteen patients were very satisfied, 10 ones were moderately satisfied, and 2 patients were not satisfied with therapy. The number of bladder catheterizations per day decreased by 51.1%. Urine volume significantly increased from 131.5±16.1 to 236±16.7 ml, intravesical pressure decreased from 23.5±4.2 to 18.5±2.1 cm H2O (by 20.3%). CONCLUSION: Chronic epidural spinal and sacral stimulation can improve the quality of life in patients with pelvic organ dysfunction. This technique may be effective for pelvic organ dysfunction caused by myelodysplasia.

Navigation versus fluoroscopy in minimalinvasive iliosacral screw placement.

INTRODUCTION: When needed operative treatment of sacral fractures is mostly performed with percutaneous iliosacral screw fixation. The advantage of navigation in insertion of pedicle screws already could be shown by former investigations. The aim of this investigation was now to analyze which influence iliosacral screw placement guided by navigation has on duration of surgery, radiation exposure and accuracy of screw placement compared to the technique guided by fluoroscopy. METHODS: 68 Consecutive patients with sacral fractures who have been treated by iliosacral screws were inclouded. Overall, 85 screws have been implanted in these patients. Beside of demographic data the duration of surgery, duration of radiation, dose of radiation and accuracy of screw placement were analyzed. RESULTS: When iliosacral screw placement was guided by navigation instead of fluoroscopy the dose of radiation per inserted screw (155.0 cGy*cm2 vs. 469.4 cGy*cm2 p < 0.0001) as well as the duration of radiation use (84.8 s vs. 147.5 s p < 0.0001) were significantly lower. The use of navigation lead to a significant reduction of duration of surgery (39.0 min vs. 60.1 min p < 0.01). The placement of the screws showed a significantly higher accuracy when performed by navigation (0 misplaced screws vs 6 misplaced screws-p < 0.0001). CONCLUSION: Based on these results minimal invasive iliosacral screw placement guided by navigation seems to be a safe procedure, which leads to a reduced exposure to radiation for the patient and the surgeon, a reduced duration of surgery as well as a higher accuracy of screw placement.

Optimization of S2-alar-iliac screw (S2AI) fixation in adult spine deformity using a comprehensive genetic algorithm and finite element model personalized to patient geometry and bone mechanical properties.

PURPOSE: To optimize the biomechanical performance of S2AI screw fixation using a genetic algorithm (GA) and patient-specific finite element analysis integrating bone mechanical properties. METHODS: Patient-specific pelvic finite element models (FEM), including one normal and one osteoporotic model, were created from bi-planar multi-energy X-rays (BMEXs). The genetic algorithm (GA) optimized screw parameters based on bone mass quality (BM method) while a comparative optimization method maximized the screw corridor radius (GEO method). Biomechanical performance was evaluated through simulations, comparing both methods using pullout and toggle tests. RESULTS: The optimal screw trajectory using the BM method was more lateral and caudal with insertion angles ranging from 49° to 66° (sagittal plane) and 29° to 35° (transverse plane). In comparison, the GEO method had ranges of 44° to 54° and 24° to 30° respectively. Pullout forces (PF) using the BM method ranged from 5 to 18.4 kN, which were 2.4 times higher than the GEO method (2.1-7.7 kN). Toggle loading generated failure forces between 0.8 and 10.1 kN (BM method) and 0.9-2.9 kN (GEO method). The bone mass surrounding the screw representing the fitness score and PF of the osteoporotic case were correlated (R2 > 0.8). CONCLUSION: Our study proposed a patient-specific FEM to optimize the S2AI screw size and trajectory using a robust BM approach with GA. This approach considers surgical constraints and consistently improves fixation performance.

Simplified S1 Vertebral Bone Quality Score in the Assessment of Patients with Vertebral Fragility Fractures.

OBJECTIVE: To evaluate the effectiveness of the S1 vertebral bone quality (VBQ) score in assessing bone quality among patients with vertebral fragility fractures (VFF). Additionally, whether the combination of S1 VBQ and Hounsfield unit (HU) values improves the predictive accuracy of VFF. METHODS: Using lumbar noncontrast computed tomography and T1-weighted magnetic resonance imaging, we measured L1 HU values, S1 VBQ, and L1-L4 VBQ. To assess their predictive performance for VFF, we constructed receiver operating characteristic curves. We also compared the diagnostic efficacy of HU values with that of S1 VBQ and L1--L4 VBQ values for the joint diagnosis of VFF. The Delong test was used to compare the value of individual or combined predictions of VFF. RESULTS: In comparison to the nonfracture group, all patients exhibited markedly elevated S1 VBQ and L1--L4 VBQ and notably reduced HU values (P < 0.001). Multivariate analysis revealed that elevated S1 VBQ, increased L1--L4 VBQ, and decreased HU values independently correlated with VFF development. The areas under the curve for VFF prediction were 0.806 for S1 VBQ, 0.799 for L1--L4 VBQ, and 0.820 for HU values. According to the Delong test, the combination of HU values with S1 VBQ/L1--L4 VBQ significantly improved the diagnostic accuracy. CONCLUSIONS: The simplified S1 VBQ is a valuable tool for predicting the occurrence of VFF and can be used as an alternative to the L1--L4 VBQ. In addition, the combination of S1 VBQ and HU values can significantly improve the predictive value of VFF.

A Whole-Spine Magnetic Resonance Imaging-Based Cross-Sectional Study of the Clinicoradiological Association of Lumbosacral Transitional Vertebra with Degenerative Disc Disease, End Plate Degeneration, Low Back Pain, and Facet Tropism.

OBJECTIVE: To understand lumbosacral transitional vertebra (LSTV)-associated degenerative pathologies and their correlation to low back pain and radicular pain. METHODS: Whole-spine magnetic resonance imaging was evaluated for disc degeneration using Pfirrmann grading, end plate changes using total end plate score (TEPS), and facet tropism in patients with low back pain and radicular pain, and their association with LSTV was analyzed. RESULTS: In group 1, LSTV was seen in 15% of patients with 83% of these patients having sacralization. Disc degeneration was seen in 58%, 51%, and 63% of patients at levels C, B, and A, respectively; patients with sacralization had significant degeneration at all 3 levels. Similarly, the total end plate score and facet tropism were significantly higher in patients with sacralization. Facet tropism was observed in 31%, 40%, and 35% of patients with no -LSTV, patients with sacralization, and patients with lumbarization, respectively. In group 2, LSTV was seen in 17% of patients with sacralization accounting for 82%. Disc degeneration was seen in 44%, 36%, and 54% patients at levels C, B, and A, respectively. No significant difference was observed in the mean total end plate score between groups. Facet tropism was identified in 89% and 81% of patients with sacralization and patients with lumbarization, respectively, compared with only 19% of patients with no LSTV. CONCLUSIONS: Patients with low back pain had a higher incidence of sacralization with corresponding disc degeneration, facet tropism ,and end plate changes. In patients with radicular pain, lumbarization was associated only with facet tropism. These findings may aid clinicians in prognostication and patient counseling.

Incidence of Suboptimal Fluoroscopic Outlet Imaging of the Sacrum and Pelvic Retroversion Necessary for Optimal Views.

OBJECTIVES: To estimate the prevalence of suboptimal fluoroscopy of sacral outlet images due to anatomic and equipment dimensions. Pelvic retroversion is hypothesized to mitigate this issue. DESIGN: In silico simulations using retrospectively collected computed tomography (CT) data from human patients. SETTING: Level I trauma center. PATIENT SELECTION CRITERIA: Adults with OTA/AO 61 pelvic ring disruptions treated with posterior pelvic fixation between July and December 2021. OUTCOME MEASURES AND COMPARISONS: C-arm tilt angles required to obtain 3 optimal fluoroscopic sacral outlet images, defined as vectors from pubic symphysis to S2 and parallel to the first and second sacral neural foramina, were calculated from sagittal CT images. A suboptimal view was defined as collision of the C-arm radiation source or image intensifier with the patient/operating table at the required tilt angle simulated using the dimensions of 5 commercial C-arm models and trigonometric calculations. Incidence of suboptimal outlet views and pelvic retroversion necessary to obtain optimal views without collision, which may be obtained by placement of a sacral bump, was determined for each view for all patients and C-arm models. RESULTS: CT data from 72 adults were used. Collision between patient and C-arm would occur at the optimal tilt angle for 17% of simulations and at least 1 view in 68% of patients. Greater body mass index was associated with greater odds of suboptimal imaging (standard outlet: odds ratio [OR] 0.84, confidence interval [CI] 0.79-0.89, P < 0.001; S1: OR 0.91, CI 0.87-0.97, P = 0.002; S2: OR 0.85, CI 0.80-0.91, P < 0.001). S1 anterior sacral slope was associated with suboptimal S1 outlet views (OR 1.12, Cl 1.07-1.17, P < 0.001). S2 anterior sacral slope was associated with suboptimal standard outlet (OR 1.07, Cl 1.02-1.13, P = 0.004) and S2 outlet (OR 1.16, Cl 1.09-1.23, P < 0.001) views. Retroversion of the pelvis 15-20 degrees made optimal outlet views possible without collision in 95%-99% of all simulations, respectively. CONCLUSIONS: Suboptimal outlet imaging of the sacrum is associated with greater body mass index and sacral slope at S1 and S2. Retroversion of the pelvis by 15-20 degrees with a bump under the distal sacrum may offer a low-tech solution to ensure optimal fluoroscopic imaging for percutaneous fixation of the posterior pelvic ring. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Utilizing robotic-assisted navigation for pelvic instrumentation in pediatric patients with neuromuscular scoliosis: a technical note and case series.

Pelvic fixation is commonly used in correcting pelvic obliquity in pediatric patients with neuromuscular scoliosis and in preserving stability in adult patients with lumbosacral spondylolisthesis or instances of traumatic or osteoporotic fracture. S2-alar-iliac screws are commonly used in this role and have been proposed to reduce implant prominence when compared to traditional pelvic fusion utilizing iliac screws. The aim of this technical note is to describe a technique for robotically navigated placement of S2-alar-iliac screws in pediatric patients with neuromuscular scoliosis, which (a) minimizes the significant exposure needed to identify a bony start point, (b) aids in instrumenting the irregular anatomy often found in patients with neuromuscular scoliosis, and (c) allows for greater precision than traditional open or fluoroscopic techniques. We present five cases that underwent posterior spinal fusion to the pelvis with this technique that demonstrate the safety and efficacy of this procedure.

Comparative Analysis of Three Posterior-Only Surgical Techniques for Isthmic L5-S1 Spondylolisthesis.

OBJECTIVE: To compare adults with isthmic L5-S1 spondylolisthesis who were treated with three different surgical techniques: PS-only, TS, and transforaminal lumbar interbody fusion/posterior lumbar interbody fusion (TLIF/PLIF). METHODS: This is a retrospective analysis of adults with L5-S1 isthmic spondylolisthesis (grade ≥2) who underwent primary all-posterior operations with pedicle screws. Patients were excluded if they had <1 year follow-up, anterior approaches, and trans-sacral fibular grafts. Patient demographics and surgical, radiographic, and clinical data were compared between groups based on the method of anterior column support: none (PS-only), TS, and TLIF/PLIF. RESULTS: Sixty patients met inclusion criteria (male patients 21, female patients 39, average age 47 ± 15 years, PS-only 16; TS 20; TLIF/PLIF 24). TS patients more commonly had high-grade slips and markedly greater slip percentage, lumbosacral kyphosis, and pelvic incidence. The three groups were similar for smoking status, visual analog scores/Oswestry Disability Index scores (VAS/ODI), surgical data, and average follow-up (40.1 ± 31.2 months). All groups had similarly notable improvements in Meyerding grade and lumbosacral angle. Slip reduction percentage was similar between groups. While there was a markedly higher overall complication rate for PS-only constructs, all groups had similarly notable improvements in ODI and VAS back scores. CONCLUSIONS: All-posterior techniques for L5-S1 isthmic spondylolisthesis resulted in excellent improvement in preoperative symptoms and HRQoL scores and similar radiographic alignment. Trans-sacral screws were more commonly used for high-grade slips. The use of anterior column support resulted in fewer overall complications than posterior-only instrumentation.

Is it necessary to extend fusion to L4 when correcting pediatric L5-S1 spondylolisthesis?

OBJECTIVE: The objective of this study was to investigate whether extending fusion to L4 is imperative in the surgical treatment of pediatric L5-S1 spondylolisthesis. METHODS: This retrospective analysis encompassed 68 pediatric cases of dysplastic L5-S1 spondylolisthesis who underwent posterior lumbar interbody fusion surgery at two hospitals. Patients were categorized into two groups based on the upper instrumented vertebra (group L4 and group L5). Data were collected from medical records and radiological images obtained preoperatively and at last follow-up. Radiographic parameters including slip percentage (SP), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), Spinal Deformity Study Group dysplastic lumbosacral angle (SDSG-LSA), pelvic tilt (PT), Dubousset's lumbosacral angle (Dub-LSA), sacral slope (SS), and severity index (SI) were measured. Surgery-related data and complication data were also collected. The incidence rates of complications were compared, including those of neurological deficit, adjacent-segment instability (ASI), and other complications. ASI was defined as progression of slippage > 3 mm or posterior opening > 5° in the adjacent segment. Clinical outcomes were assessed with the numeric rating scale (NRS) and the Oswestry Disability Index (ODI) scores. The follow-up period for all patients lasted a minimum of 2 years. RESULTS: Among all 68 patients, group L4 consisted of 15 patients and group L5 comprised 53 patients. The patients included in both groups had comparable baseline demographic characteristics and radiographic parameters. Postoperative SP and SDSG-LSA were significantly lower in group L5 (p < 0.05). No other postoperative radiographic differences were observed between groups. One patient in group L4 and 3 patients in group L5 experienced transient neurological deficits (p > 0.05). There were 13 cases of ASI in group L5 compared with none in group L4 (24.5% vs 0%, p > 0.05). Of the 13 patients with ASI, 4 underwent revision surgery due to L4-5 level instability and clinical symptoms. The remaining individuals exhibited no symptoms, and regular annual follow-up assessments are being conducted for all patients. The NRS and ODI scores at final follow-up did not exhibit any significant differences between the two groups. CONCLUSIONS: Fusion to L5 could achieve comparable satisfactory results to fixation to L4, albeit with increased likelihood of ASI. Extension of fusion to L4 may not be necessary for most patients with pediatric L5-S1 spondylolisthesis.

Acontractile detrusor as an initial presentation of sacral spinal cord lesion: Case series.

OBJECTIVES: This study aims to investigate cases of acontractile bladder as the initial presentation of benign and malignant spinal conditions. The focus is on the challenges in making a diagnosis and the importance of a thorough neurological evaluation. METHODS: We conducted a retrospective case series involving three patients who exhibited symptoms of acontractile bladder. Detailed clinical histories, urodynamic studies, and imaging techniques such as lumbosacral magnetic resonance imaging (MRI) were analyzed. Histopathological findings from relevant biopsies were also taken into account. RESULTS: Case 1: A 14-year-old female presented with urinary retention, back pain, and an acontractile bladder on urodynamic study. Further examination, including lumbosacral MRI and histopathology, confirmed a diagnosis of metastatic Ewing's Sarcoma. Case 2: A 39-year-old female with urinary incontinence and elevated post-void residual exhibited delayed bladder sensation. Lumbar spine MRI revealed a grade I Schwannoma after surgical resection. Case 3: A 15-year-old male with lower urinary tract symptoms and an acontractile detrusor on urodynamic study was found to have a Tarlov cyst on lumbosacral MRI. CONCLUSION: Atonic or Underactive bladder syndrome may be the initial presentation of a serious spinal condition. Complete neurological evaluation is mandatory if no obvious clinical cause.

L4 fixation is not necessary in L5-Iliac spinopelvic fixation after trauma, but coadjutant transilio-transsacral fixation is.

INTRODUCTION: Spinopelvic dissociation (SPD) is a severe injury characterized by a discontinuity between the spine and the bony pelvis consisting of a bilateral longitudinal sacral fracture, most of the times through sacral neuroforamen, and a horizontal fracture, usually through the S1 or S2 body. The introduction of the concept of triangular osteosynthesis has shown to be an advance in the stability of spinopelvic fixation (SPF). However, a controversy exists as to whether the spinal fixation should reach up to L4 and, if so, it should be combined with transiliac-transsacral screws (TTS). OBJECTIVE: The purpose of this study is to compare the biomechanical behavior in the laboratory of four different osteosynthesis constructs for SPD, including spinopelvic fixation of L5 versus L4 and L5; along with or without TTS in both cases. MATERIAL AND METHODS: By means of a formerly described method by the authors, an unstable standardized H-type sacral fracture in twenty synthetic replicas of a male pelvis articulated to the lumbar spine, L1 to sacrum, (Model: 1300, SawbonesTM; Pacific Research Laboratories, Vashon, WA, USA), instrumented with four different techniques, were mechanically tested. We made 4 different constructs in 5 specimen samples for each construct. Groups: Group 1. Instrumentation of the L5-Iliac bones with TTS. Group 2. Instrumentation of the L4-L5-Iliac bones with TTS. Group 3. Instrumentation of L5-Iliac bones without TTS. Group 4: Instrumentation of L4-L5-Iliac bones without TTS. RESULTS AND CONCLUSIONS: According to our results, it can be concluded that in SPD, better stability is obtained when proximal fixation is only up to L5, without including L4 (alternative hypothesis), the addition of transiliac-transsacral fixations is essential.