Clinical study on freehand of bicortical sacral screw fixation with the assistance of torque measurement device.

BACKGROUND: Sacral screw loosening is a typical complication after internal fixation surgery through the vertebral arch system. Bicortical fixation can successfully prevent screw loosening, and how improving the rate of bicortical fixation is a challenging clinical investigation. OBJECTIVE: To investigate the feasibility of improving the double corticality of sacral screws and the optimal fixation depth to achieve double cortical fixation by combining the torque measurement method with bare hands. METHODS: Ninety-seven cases of posterior lumbar internal fixation with pedicle root system were included in this study. Based on the tactile feedback of the surgeon indicating the expected penetration of the screw into the contralateral cortex of the sacrum, the screws were further rotated by 180°, 360°, or 720°, categorized into the bicortical 180° group, bicortical 360° group, and bicortical 720° group, respectively. Intraoperatively, the torque during screw insertion was recorded. Postoperatively, the rate of double-cortex engagement was evaluated at 7 days, and screw loosening was assessed at 1 year follow-up. RESULTS: The bicortical rates of the 180° group, 360° group, and 720° group were 66.13%, 91.18% and 93.75%, respectively. There were statistically significant differences between the 180° group and both the 360° and 720° groups (P < 0.05). However, there was no statistically significant difference between the 360° group and the 720° group (P > 0.05).The rates of loosening of sacral screws in the 180° group, 360° group, and 720° group were 20.97%, 7.35% and 7.81%, respectively. There were statistically significant differences between the 180° group and both the 360° and 720° groups (P < 0.05). However, there was no statistically significant difference between the 360° group and the 720° group (P > 0.05). The bicortical 360° group achieved a relatively satisfactory rate of dual cortical purchase while maintaining a lower rate of screw loosening. CONCLUSION: Manual insertion of sacral screws with the assistance of a torque measurement device can achieve a relatively satisfactory dual cortical purchase rate while reducing patient hospitalization costs.

The optimal introversion angle and length of pedicle screw to avoid L1-S1 vascular damage.

BACKGROUND: posterior pedicle screw fixation is common method, one of the most severe complications is iatrogenic vascular damage, no report investigated association of different introversion angles (INTAs) and length of pedicle screw. The aims were to investigate the optimal introversion angle and length of pedicle screw for improving the safety of the operation, and to analyze the differences of vascular damage types at L1-S1. METHODS: Lumbar CT imaging data from110 patients were analyzed by DICOM software, and all parameters were measured by new Cartesian coordinate system, INTAs (L1-L5:5°,10°,15°,S1: 0°, 5°,10°,15°), DO-AVC (the distance between the origin (O) with anterior vertebral cortex (AVC)), DAVC-PGVs (the distance between AVC and the prevertebral great vessels (PGVs)), DO-PGVs (the distance between the O and PGVs). At different INTAs, DAVC-PGVs were divided into four grades: Grade III: DAVC-PGVs ≤ 3 mm, Grade II: 3 mm < DAVC-PGVs ≤ 5 mm, Grade I: DAVC-PGVs > 5 mm, and N: the not touching PGVs. RESULTS: The optimal INTA was 5° at L1-L3, the left was 5° and the right was 15° at L4, and screw length was less than 50 mm at L1-L4. At L5, the left optimal INTA was 5° and the right was 10°, and screw length was less than 45 mm. The optimal INTA was 15° at S1, and screw length was less than 50 mm. However, screw length was less than 40 mm when the INTA was 0° or 5° at S1. CONCLUSIONS: At L5-S1, the risk of vascular injury is the highest. INTA and length of the pedicle screw in lumbar operation are closely related. 3 mm interval of screw length may be more preferable to reduce vascular damage.

Beyond the Tailbone: A Family's Journey Through Caudal Regression Syndrome-A Triple Sibship.

BACKGROUND: Caudal regression syndrome (CRS), also known as caudal agenesis, results from abnormal development of the caudal aspect of the spinal cord and vertebral column due to an earlier abnormality of gastrulation. RESULTS: This report showcases a unique scenario where three siblings, devoid of any prior family history or identifiable risk factors, exhibit symptoms of CRS and receive care at a government-run tertiary facility dedicated to children's health. In establishing a concrete diagnosis, we relied on skeletal surveys, comprehensive symptom evaluation, and medical history assessment. Additionally, we recommended further investigation through magnetic resonance imaging and genetic testing to attain a more in-depth understanding and confirmation of the condition. Unfortunately, the financial constraints faced by the parents led to the unfeasibility of pursuing these advanced diagnostic options. Given the rarity of this syndrome and the limited existing literature, our report is a significant contribution. It marks the first comprehensive exploration of CRS from the genetic and familial predisposition perspective, shedding new light on this rare condition. CONCLUSION: This case series pioneers our understanding of the familial and genetic connections between CRS and sacral agenesis. Strikingly, each subsequent generation has experienced more severe manifestations earlier, furnishing compelling evidence that underpins the genetic predisposition to CRS.

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.

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.

Reciprocal Changes in Sagittal Spinal Alignment After L5-S1 Anterior Lumbar Interbody Fusion.

OBJECTIVE: Degenerative diseases of the lumbar spine decrease lumbar lordosis (LL). Anterior lumbar interbody fusion (ALIF) at the L5-S1 disc space improves segmental lordosis, LL, and sagittal balance. This study investigated reciprocal changes in spinopelvic alignment after L5-S1 ALIF. METHODS: A retrospective chart review identified patients who underwent L5-S1 ALIF with or without posterior fixation at a single institution (November 1, 2016 to October 1, 2021). Changes in pelvic tilt, sacral slope, proximal LL (L1-L4), distal LL (L4-S1), total LL (L1-S1), segmental lordosis, pelvic incidence-LL mismatch, thoracic kyphosis, cervical lordosis, and sagittal vertical axis were measured on preoperative and postoperative radiographs. RESULTS: Forty-eight patients were identified. Immediate postoperative radiographs were obtained at a mean (SD) of 17 (20) days after surgery; delayed radiographs were obtained 184 (82) days after surgery. After surgery, patients had significantly decreased pelvic tilt (15.71° [7.25°] vs. 17.52° [7.67°], P = 0.003) and proximal LL (11.86° [10.67°] vs. 16.03° [10.45°], P < 0.001) and increased sacral slope (39.49° [9.27°] vs. 36.31° [10.39°], P < 0.001), LL (55.35° [13.15°] vs. 51.63° [13.38°], P = 0.001), and distal LL (43.17° [9.33°] vs. 35.80° [8.02°], P < 0.001). Segmental lordosis increased significantly at L5-S1 and decreased significantly at L2-3, L3-4, and L4-5. Lordosis distribution index increased from 72.55 (19.53) to 81.38 (22.83) (P < 0.001). CONCLUSIONS: L5-S1 ALIF was associated with increased L5-S1 segmental lordosis accompanied by pelvic anteversion and a reciprocal decrease in proximal LL. These changes may represent a reversal of compensatory mechanisms, suggesting an overall relaxation of spinopelvic alignment after L5-S1 ALIF.

Treatment Outcomes of Lower Urinary Tract Symptoms due to Fragility Sacral Fractures: A Review of Eight Patients and Literature.

BACKGROUND: Sacral fractures can cause lower urinary tract symptoms (LUTS) due to damage to the cauda equina. While several studies have reported on sacral fractures due to high-energy trauma, those due to fragility fractures have only been reported in case reports and their clinical differences are not well known. This study aimed to investigate the clinical characteristics of LUTS caused by fragility sacral fractures and propose a novel treatment strategy. METHODS: This study is retrospective, uncontrolled, clinical case series. The inclusion criteria were sole sacral fractures due to low-energy trauma and appearance of LUTS after injury. Patients with additional spinal fractures or combined abdominal or pelvic organ injuries that could cause LUTS were excluded. Improvement in LUTS, period from onset to improvement, and imaging findings were recorded. RESULTS: Eight patients met the inclusion criteria (4 surgical and 4 conservative treatment cases). Six patients showed improvement in LUTS. In surgical cases, the mean period from onset of LUTS to surgery and from onset of LUTS to improvement was 14.5 and 21.5 days, respectively. Intraoperative rupture or laceration of the dural sac was not observed. In 2 conservatively improved cases, the period from onset to improvement of LUTS was 14 and 17 days. CONCLUSIONS: LUTS can improve even with conservative treatment and should be utilized as the primary choice. LUTS caused by severe sacral canal deformity and stenosis can be reversible, and the decision to perform surgical treatment is still timely if LUTS do not improve with conservative treatment for several weeks.

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.

3D CT modeling demonstrates the anatomic feasibility of S1AI screw trajectory for spinopelvic fixation in neuromuscular scoliosis.

PURPOSE: In patients with neuromuscular scoliosis undergoing posterior spinal fusion, the S2 alar iliac (S2AI) screw trajectory is a safe and effective method of lumbopelvic fixation but can lead to implant prominence. Here we use 3D CT modeling to demonstrate the anatomic feasibility of the S1 alar iliac screw (S1AI) compared to the S2AI trajectory in patients with neuromuscular scoliosis. METHODS: This retrospective study used CT scans of 14 patients with spinal deformity to create 3D spinal reconstructions and model the insertional anatomy, max length, screw diameter, and potential for implant prominence between 28 S2AI and 28 S1AI screw trajectories. RESULTS: Patients had a mean age of 14.42 (range 8-21), coronal cobb angle of 85° (range 54-141), and pelvic obliquity of 28° (range 4-51). The maximum length and diameter of both screw trajectories were similar. S1AI screws were, on average, 6.3 ± 5 mm less prominent than S2AI screws relative to the iliac crests. S2AI screws were feasible in all patients, while in two patients, posterior elements of the lumbar spine would interfere with S1AI screw insertion. CONCLUSION: In this cohort of patients with neuromuscular scoliosis, we demonstrate that the S1AI trajectory offers comparable screw length and diameter to an S2AI screw with less implant prominence. An S1AI screw, however, may not be feasible in some patients due to interference from the posterior elements of the lumbar spine.

Clinical Features and Therapeutic Process of Sacral Fatigue Fractures in Adolescents.

BACKGROUND: Sacral fatigue fractures are a rare injury but should be considered as a differential diagnosis for low back and buttock pain in young adults. Collective reports are limited, most of which have focused on long-distance runners. PURPOSE: To investigate the characteristics of sacral fatigue fractures in adolescents. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: We analyzed patient background characteristics, physical examination and imaging findings, and treatment courses of those diagnosed with sacral fatigue fractures using magnetic resonance imaging. RESULTS: Among 34 patients with sacral fatigue fractures, 15 and 19 were male and female patients, respectively, with an age range of 11 to 19 years (mean age, 15.0 years). Almost all patients were athletes, and 29 patients performed their sport ≥5 times a week. Long-distance runners were the most commonly affected, comprising 7 patients, and participants in other common sports such as baseball (6 patients), basketball (4 patients), and soccer (3 patients) were also affected. Physical examination revealed tension sign (Lasègue test) on the affected side in 6 patients and tight hamstrings in 24 patients. Imaging findings included 18 patients with right-side involvement, 12 with left-side involvement, and 4 with involvement on both sides. In 11 patients, spina bifida occulta was observed at S1 and 8 patients had a history of lumbar spondylolysis with 4 patients having concurrent sacral fatigue fractures. Physical therapy was performed concurrently with the cessation of exercise, and return to exercise was permitted if the pain had been relieved after 1 month. All patients returned to sports at a median of 48 days (range, 20-226 days) after symptom onset. However, 2 patients experienced recurrence (1 patient on the ipsilateral side and 1 patient on the contralateral side). CONCLUSION: Sacral stress fractures are not limited to long-distance runners in this population and can manifest as lower back pain or buttock pain in athletes participating in a variety of sports. Although the course of treatment was generally good, the possibility of recurrence must always be considered.

Modified S1 Pedicle Subtraction Osteotomy.

STUDY DESIGN: Surgical technique video. OBJECTIVE: To report a surgical technique to revise patients with previous fusions at L4-S1 leading to an iatrogenic flat back and sagittal imbalance using L5-S1 transforaminal interbody fusion combined with a small S1 corner osteotomy. BACKGROUND: This is a case of a woman (51 y old) with a history of multiple lumbar surgeries, severe back pain, sagittal imbalance, and loss of lordosis. METHODS: We describe a feasible revision technique in a complex patient with the goal of attaining optimal distribution of lumbar lordosis and sagittal balance through a modified S1 pedicle subtraction osteotomy, and the use of an interbody cage to enhance the fusion rate and facilitate closure of the 3-column osteotomy. RESULTS: The preoperative patient lordosis angle of 31 degrees at L1-L4 and 16 degrees at L4-S1 became 12 degrees at L1-L4 and 44 degrees at L4-S1 postoperatively. CONCLUSION: The combination of L5-S1 transforaminal interbody fusion and S1 corner osteotomy is a feasible technique for the restoration of lumbar lordosis in patients with previous fusion and consequent loss of lordosis.

S1 vertebral bone quality score independently predicts pedicle screw loosening following surgery in patients with adult degenerative scoliosis.

BACKGROUND CONTEXT: MRI-based vertebral bone quality (VBQ) score is an effective predictor of pedicle screw loosening after lumbar fusion surgery and has been recognized as a valuable tool for assessing preoperative bone quality. Due to the lateral curvature of lumbar spine of degenerative scoliosis, accurate measurement of VBQ score by conventional measurement methods that capture MRI signal intensity at L1-4 may be limited under certain conditions. To this end, a new simplified S1 VBQ score method has been proposed, which is comparable to the previous L1-4 VBQ score or S1 Hounsfield unit (HU) value, and has high accuracy and reliability. PURPOSE: To evaluate the predictive value of MRI-based S1 VBQ score for pedicle screw loosening following surgery for adult degenerative scoliosis (ADS). STUDY DESIGN/SETTING: Retrospective single-center cohort. PATIENT SAMPLE: We reviewed 92 patients who underwent posterior lumbar interbody fusion (PLIF) with pedicle screw fixation for ADS between January 2017 and January 2020. OUTCOME MEASURES: Association between S1 VBQ score and pedicle screw loosening following surgery for ADS. METHODS: We retrospectively reviewed the records of all patients who performed PLIF between January 2017 and January 2020. The clear zone around pedicle screws≥1 mm can be identified as screw loosening. The S1 VBQ score is calculated from the S1 central-based noncontrast T1-weighted magnetic resonance imaging (MRI). The signal intensity (SI) of the cerebrospinal fluid (CSF) was then measured using ROI placed at the L3 level to normalize the results. Multivariate logistic regression analysis was performed to identify independent risk factors for screw loosening. Then, constructed a receiver operating characteristic (ROC) curve and determined the threshold (cut-off) of VBQ score with high sensitivity and specificity based on Youden Index. RESULTS: A total of 92 patients were included, including 34 males and 58 females. The mean age of the patients was 61.23±1.23 years old. At 1-year follow-up, the screw loosening rate was 56.5% (52/92). The age and levels of fixation were higher in the loosening group than in the nonloosening group (p=.036, p=.025). Patients in the loosening group had a greater VBQ score compared to patients in the nonloosening group (3.31±0.41 vs 3.01±0.28, p=.001). Multivariate logistic regression analysis showed that advanced age (OR, 1.090; 95% CI 1.005-1.183; p=.039) and higher VBQ score (OR, 5.778; 95% CI 2.889-16.177; p=.001) were independent risk factors for screw loosening. In addition, the ROC curve were created to assess the role of VBQ score as predictors of screw loosening with a diagnostic accuracy of 74.6% (95% CI 64.2%-85.1%).The most suitable threshold for the VBQ score as determined by the Youden Index was 3.175 (sensitivity: 76.0%, specificity: 83.3%). CONCLUSIONS: Higher S1 VBQ score was significantly associated with pedicle screw loosening following surgery for ADS. The S1 VBQ score can be used as an effective preoperative predictor, which has the potential clinical application.

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.

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.

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 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.

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.