T1 Pelvic Angle Research Articles

Associations between NCLBP, spinal sagittal alignment and age groups: a cross-sectional cohort study.

Nonspecific chronic low back pain (NCLBP) is one of the most common manifestations of degenerative spondylitis. It affects many patients of all ages and seriously interferes with quality of life. However, the associations between NCLBP, sagittal alignment and age remain unclear. We aimed to investigate the typical features of sagittal alignment in individuals with NCLBP and to discuss the relationships between age and these NCLBP-related changes in sagittal alignment. We measured the sagittal parameters of patients with NCLBP and investigated their sagittal alignment and compensatory mechanisms by comparing them with those of asymptomatic individuals. A total of 905 elderly patients (≥ 50years old) and 1296 young patients (< 50years old) were included. An analysis of sagittal parameters revealed that elderly patients with NCLBP had a smaller lumbar lordosis (LL, p = 0.001) and a greater T1 pelvic angle (TPA, p < 0.001). Age was significantly correlated with the TPA (rs = 0.549, p < 0.001) and pelvic tilt (PT, rs = 0.471, p < 0.001). The AUC value of the TPA was 0.782 (95% CI 0.764 to 0.799). Although decreased lumbar lordosis is the most typical sagittal feature in patients with NCLBP, there are still differences in sagittal alignment between different ages. Compared with young patients, elderly patients with NCLBP more commonly present with a decompensated pattern of the anterior inclination of the trunk as the main sagittal alignment abnormality. TPA is more predictive than LL for the diagnosis of geriatric NCLBP.

Maintaining stability at the lumbosacral-pelvic region in adult spinal deformity surgery without sacroiliac joint fusion: are 4 pelvic screws superior to 2 pelvic screws?

The objective of this study was to compare a multiple pelvic screw fixation strategy (dual bilateral 4 pelvic screw fixation [4PvS]) with the use of single bilateral 2 pelvic screw fixation (2PvS), with the aim of addressing lumbosacral junction stability. This analysis is a single-center, retrospective review of ASD patients treated between 2015 and 2021. All patients had a minimum 2-year follow-up and spinal fusion to the sacrum without sacroiliac fusion and met at least one radiographic and procedural criterion: pelvic incidence-lumbar lordosis ≥ 20°, T1 pelvic angle ≥ 20°, sagittal vertical axis ≥ 7.5 cm, scoliosis ≥ 50°, three-column osteotomy, or spinal fusion of ≥ 8 levels. Two sacropelvic fixation methods were compared: 4PvS versus 2PvS. Primary outcomes included spinal implant-related reoperation and screw breakage, while secondary outcomes included reoperation for symptomatic pelvic screws, screw loosening or bending, L5-S1 pseudarthrosis, and patient-reported outcomes. Propensity score matching and inverse probability of treatment weighting (IPTW) were used to minimize selection bias and estimate causal treatment effects. Clinical outcomes were assessed using conditional multivariable logistic regression. In this study of 406 patients (67.98% female, mean age 64.48 years), 349 patients (85.96%) received 2PvS and 57 (14.04%) received 4PvS. Age (OR 1.081, 95% CI 1.027-1.145) and total number of osteotomies (OR 1.180, 95% CI 1.048-1.355) emerged as independent predictors of receiving the 4PvS technique. In unmatched cohorts (n = 406), 2-year implant-related reoperation rates (p = 0.1896) and pelvic screw breakage rates (p = 0.2498) were not significantly different between groups. However, in the 4:1 propensity score-matched cohort, the 2-year reoperation rate (10.53% for 2PvS vs 3.51% for 4PvS; OR 3.27, 95% CI 1.10-9.74 [p = 0.0312]) and the pelvic screw breakage rate (9.21% for 2PvS vs 3.51% for 4PvS; OR 2.87, 95% CI 1.08-7.63 [p = 0.0349]) were significantly higher among the 2PvS groups. The IPTW analysis confirmed these findings, with reoperation rates of 10.45% for 2PvS and 1.18% for 4PvS (p = 0.0244) and pelvic screw breakage rates of 8.72% and 1.18%, respectively (p = 0.0477). A safety assessment revealed comparable operative times and intra- and perioperative complications between the two techniques. Patients who underwent 4PvS demonstrated significantly lower 2-year implant-related reoperation and pelvic screw breakage rates compared with 2PvS, with no differences in intraoperative or perioperative complications.

Impact of the hip osteoarthritis on sagittal spine-pelvis alignment parameters in lumbar spinal stenosis with sagittal malalignment: a propensity score matching study.

There is a paucity of data regarding the sagittal spine-pelvis-leg alignment and the compensatory mechanisms in patients with lumbar spinal stenosis (LSS) and hip osteoarthritis (HOA). In this study, we aim to evaluate the association of HOA with sagittal spine-pelvis alignment parameters in a population of patients with lumbar spinal stenosis and sagittal malalignment. We retrospectively analyzed a cohort of prospectively enrolled patients with degenerative LSS and sagittal malalignment between January 2019 and December 2023. Radiographic parameters evaluated were pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, sagittal vertical axis (SVA), T1-pelvic angle (T1PA), sacrofemoral angle (SFA), pelvic obliquity (PO), and femoral inclination (FI). HOA was graded by Kellgren-Lawrence (K/L) grades and divided into low-grade HOA (LOA; grade 0-2) and severe HOA (SOA; grade 3 or 4) groups. LOA group patients were propensity-score matched (PSM) 1:1 to SOA group patients based on age and PI. Univariate, multivariate, and subgroup analyses were used to analyze the association between HOA and sagittal malalignment. Out of 379 patients, 116 with LOA and 116 with SOA were analyzed after propensity score matching for age and PI. SOA patients exhibited significantly lower FPA (184.01 ± 9.97 vs 186.78 ± 10.11, p = 0.036), higher SS (33.05 ± 9.38 vs. 30.51 ± 9.47, p = 0.042), and lower PT (16.28 ± 8.67 vs. 18.53 ± 7.84, p = 0.040) compared to the LOA group. Subgroup analysis revealed that SOA patients with a SVA > 4cm had significantly higher PI (51.49 ± 11.64 vs. 47.83 ± 10.73, p = 0.025) and PT (18.71 ± 8.76 vs. 14.67 ± 8.56, p < 0.001), which were not observed in the LOA group. Multivariable linear regression analysis revealed that a greater Kellgren-Lawrence (K/L) Grade was significantly associated with a higher SVA after adjusting for age, BMI, and PI. In this PSM study, patients with SOA exhibit reduced pelvic tilt and hip extension in standing positions compared to those with LOA. Additionally, the SOA patients had worse global sagittal alignment than their LOA counterparts.

Surgical treatment algorithm for thoracic and lumbar hyperkyphosis in pediatric population.

There is no standardized and universally accepted surgical treatment for thoracic and lumbar hyperkyphosis in children. A surgical treatment algorithm was developed to aid in the choice of the appropriate corrective technique. A retrospective analysis was conducted of patients younger than 18years who underwent primary correction surgery and posterior fusion for thoracic and lumbar hyperkyphosis. Patients were categorized according to the classification of Rajasekaran et al. and divided into 2 groups: a posterior column osteotomies (PCO) group and a three-column osteotomies (3CO) group. We analyzed the angularity and flexibility of the curve, global sagittal balance, and preoperative neurological status of the patient. Forty-nine patients were included. The mean age was 12.8years (1-18) and the mean preoperative kyphosis was 93.5° (40°-175°). In the PCO group (N = 30), the sagittal deformity angular ratio (DAR) was less than 16.5 in 26 patients (86.6%), while in the 3CO group (N = 19), sagittal DAR was greater than 16.5 in 17 patients (89.4%). In the PCO group (N = 28), the T1-Pelvic angle (TPA) was less than 17° in 19 patients (67.8%), while in the 3CO group (N = 15), TPA was greater than 17° in 10 patients (66.6%). Five patients (10.2%) had recent-onset or progressive neurological alteration, all of them (100%) required 3CO. An algorithm for kyphosis was developed based on the classification by Rajasekaran et al., preoperative analysis of the angularity and flexibility of the curve, global sagittal balance and neurological status of the patient, to aid in the choice of the appropriate corrective osteotomy. IV.

Relationship Between the Axis of the Humeral Heads and the Spinal Sagittal Alignment in Asymptomatic Volunteers.

Background Currently, there is no known correlation between relevant parameters of respective non-adjacent spinal segments, which suggests the possibility of a third external factor. To our knowledge, no study has examined the humeral head position in consideration of spinal sagittal alignment.This study aims to establish new parameters related to the humeral head axis and evaluate the relationship between the axis of the humeral head and spinal sagittal alignment in asymptomatic volunteers. Methods Standing posteroanterior and lateral radiographs of the entire spine were obtained from 62 asymptomatic volunteers. We analyzed the relationship of the newly established parameters related to the humeral head axis We analyzed the relationship of the newly established parameters related to the humeral head axisand other established spinal parameters. The new parameters are: shoulder tilt (ST: the angle between a line drawn from the center of the humeral head to the center of the superior endplate of T1 and vertical line through the center of the humeral head), shoulder incidence (SI: the angle between a line perpendicular to the upper endplate of the T1 vertebra and a line joining the center of the upper endplate of the T1 vertebra and the axis of the humeral head), shoulder pelvic angle (SPA: the angle between a line joining the axis of the humeral head and the femoral head and a line joining the axis of the femoral heads and the center of the upper endplate of the S1 vertebra), C2 shoulder angle (C2SA: the angle between a line joining the C2 body center and the axis of the humeral head and a line joining the axis of the humeral head and the center of the upper endplate of the T1 vertebra). Statistical analysis was performed using Pearson's correlation coefficient. Results Mean ST, SI, SPA, and C2SA were 20.0±20.6°, 43.7±21.6°, 7.7±6.6°, and 17.8±13.5° respectively. The SI was found to be correlated with pelvic tilt (r=0.373), lumbar lordosis (r=0.351), and thoracic kyphosis (r=0.469). Pelvic incidence was correlated with SPA (r=0.724), T1 pelvic angle (r=0.691), and C2 pelvic angle (r=0.667). Correlations were observed between SPA and T1PA (r=0.955) and C2PA (r=0.956), and between TIPA and C2PA (r=0.985). Conclusions This report introduced novel parameters related to humeral head position and confirmed their correlation with sagittal alignment from the cervical spine to the pelvis. Humeral head position may play a role in maintaining spinal sagittal balance.

Course and Predictors of Adult Spinal Sagittal Disorders: A 10-year Prospective Case Series.

Prospective case series. To study the natural course of adult spinal deformity (ASD) over a10-year period and the determinants associated with postural malalignments. ASD comprises a heterogeneous spectrum of abnormalities of the thoracolumbar spine throughout adulthood. Radiographic deterioration of sagittal alignment is a combination of decreased lumbar lordosis (LL), PI-related retroversion of the pelvic tilt (PT), anteriorizing sagittal vertical axis (SVA) and increased T1 pelvic angle (TPA). The full spine radiographs were taken to measure the SRS-Schwab sagittal modifiers PI-LL, PT and SVA to measure the possible change in severity of deformity from the 204 volunteer participants (mean age 62.7 years, 61% female), which were 32% of the 637 consecutive patients with prolonged back pain who originally joined the study in 2012-2013. Each participant completed the Scoliosis Research Society 22r (SRS-22r) questionnaire. The mean change in the SRS-Schwab score was 0.4 units (baseline 1.1 vs. follow-up 1.5, P < 0.001) implying deterioration of the spinal deformity. The SRS-Schwab score decreased (n=76, 37%), remained the same (n=102, 50%) or improved (n=26, 13%). Four predictive factors for a change of sagittal alignment were found, of which the poor score in the SRS-22r function domain (P=0.049) and severe pelvic tilt (PT greater than 30°, P=0.006) predicted the change. This study showed the variability in how sagittal alignment of the spine change during the 10-year follow-up period. The ASD patients with poor self-assessed functional ability and disturbed pelvic position were associated with the risk of deterioration in spinopelvic alignment. The diversity in the natural course of ASD and the known risk factors highlights the need for tailored advice when planning preventive treatment procedures for ASD patients. 3.

Characterization of Patients with Poor Clinical Outcome after Adult Spinal Deformity Surgery: A Multivariate Analysis of Mean 8-Year Follow-Up Data.

Background/Objective: Limited data exist regarding the long-term clinical outcomes and related factors after adult spinal deformity (ASD) surgery. This study aims to characterize patients who experienced poor clinical outcomes during long-term follow-up after ASD surgery. Methods: Patients who underwent ASD surgery with ≥5-vertebra fusion including the sacrum and ≥5-year follow-up were included. They were divided into two groups according to the Oswestry Disability Index (ODI) at the last follow-up: group P (poor outcome, ODI > 40) and group NP (non-poor outcome, ODI ≤ 40). Clinical variables, including patient factors, surgical factors, radiographic parameters, and mechanical complications (proximal junctional kyphosis [PJK] and rod fracture), were compared between the groups. Results: A total of 105 patients were evaluated, with a mean follow-up of 100.6 months. The mean age was 66.3 years, and 94 patients (89.5%) were women. There were 52 patients in group P and 53 patients in group NP. Univariate analysis showed that low T-score, postoperative correction relative to age-adjusted pelvic incidence-lumbar lordosis, T1 pelvic angle (TPA) at last follow-up, and PJK development were significant factors for poor clinical outcomes. Multivariate analysis identified PJK as the single independent risk factor (odds ratio [OR] = 3.957 for PJK development relative to no PJK, OR = 21.141 for revision surgery for PJK relative to no PJK). Conclusions: PJK development was the single independent factor affecting poor clinical outcomes in long-term follow-up. Therefore, PJK prevention appears crucial for achieving long-term success after ASD surgery.

T1 Pelvic and Lumbar Pelvic Angles Normative Values: A Prospective Cohort Study of 472 Asymptomatic Volunteers.

Cross-sectional analysis of a prospectively enrolled cohort. Determine the normative values of the T1 Pelvic Angle (TPA) and Lumbar Pelvic Angle (LPA) in an asymptomatic cohort of volunteers. The TPA and LPA have been introduced as sagittal spino-pelvic parameters to guide correction of adult spinal deformity. Suggested values for these parameters were derived from linear regressions based on Oswestry Disability Index scores from adult spinal deformity patients. While a few studies have evaluated the normative value of TPA, none have evaluated the LPA in asymptomatic individuals. TPA and LPA were measured on radiographs of 472 asymptomatic volunteers between 20 and 40 years old. TPA and LPA were calculated as originally described from the centroid of T1 and L1 respectively, to the center of the femoral head to the midpoint of the sacral endplate. TPA and LPA were also evaluated using the midpoint of the superior endpoint as a surrogate to the centroid of the vertebra to compare these two measurement techniques. TPA and LPA normative values were respectively 7.3 [6.8-7.8] and 6.3o [5.9-6.7]. There was no statistically significant difference between using the centroid of T1 or L1 versus using the midpoint of the superior endplate with respective results of 7.5o [7.0-8.0] (P=0.55) and 6.1o [5.6-6.5] (P=0.43). TPA was significantly different between Roussouly types 1-2-3 versus type 4 with respective results of of 6.7o, 7.2o, 6.5o and 9.2o (P<0.001). The same difference was observed for the LPA with normative results of 3.8o, 5.1o, 5.8o and 9.3o (P<0.001), respectively, for Roussouly types 1,2,3 and 4. TPA and LPA normative values are 7o and 6o, respectively, and vary between Roussouly morphotypes 1,2 and 3 versus type 4. Using the midpoint of the superior endplate of T1 and L1 versus the centroid yielded similar results and therefore could be easier to use intraoperatively.

An effective strategy for treatment of severe kyphosis secondary to ankylosing spondylitis: one-level modified osteotomy combined with shoulders lifting correction method

BackgroundSevere kyphosis is a common condition in patients with advanced ankylosing spondylitis (AS). Although two-level osteotomy may serve as a potential alternative, it is often associated with increased blood loss and elevated surgical risks. To date, the optimal treatment for the challenging condition remains unclear. This study aims to introduce an effective strategy for the treatment of severe kyphosis secondary to AS, using one-level modified osteotomy combined with shoulders lifting correction method.MethodsSeventy AS kyphosis who were treated with the strategy from 2012 to 2022, were reviewed retrospectively. All patients were followed up for a minimum duration of 2 years. Spinal and pelvic parameters were measured, including pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumber lordosis (LL), PI and LL mismatch (PI-LL), thoracic kyphosis, global kyphosis (GK), T1 pelvic angle (TPA), sagittal vertical axis (SVA), osteotomized vertebral angle (OVA), and chin-brow vertical angle (CBVA). Parameters of local osteotomized complex were measured and calculated, including the height of osteotomized complex and the length of spinal cord shortening. Clinical outcome was evaluated using Scoliosis Research Society-22 and Oswestry Disability Index scores.ResultsSeventy patients with average age of 39.8 years were followed-up for 29.3 months. Average operation time was 373.5 min, and average blood loss was 751.0 ml. Postoperatively, sagittal balance was successfully restored. GK decreased from 90.6° to 35.6°, LL decreased from 8.0° to -35.1°, TPA decreased from 56.8° to 27.8°, and SVA decreased from 24.4 cm to 8.7 cm (P < 0.05). A harmonious and matched spinopelvic alignment was achieved. PT decreased from 37.2° to 26.3°, PI-LL decreased from 54.1° to 10.2°, and SS increased from 9.2° to 19.7°(P < 0.05). Horizontal vision was obtained with postoperative CBVA of 8.8°. Average OVA correction was up to 47.3°, and the spinal cord was shortened by 24.3 mm, with a shortening rate of 36.0%. All patients demonstrated a favorable clinical outcome. No permanent nerve damage, screw loosening, rod breakage and main vascular injury were observed. One case required revision surgery due to screw cap loosening and delayed union. Solid bone fusion was achieved in all other patients.ConclusionsOne-level modified osteotomy combined with shoulders lifting correction method is a safe and effective strategy for the treatment of severe AS kyphosis. This strategy offers a promising alternative for managing severe AS kyphosis, and may be particularly well-suited for individuals with concurrent osteoporosis.Level of evidenceLevel IV, therapeutic study.

Radiographic Alignment in Deformity Patients Treated With Personalized Interbody Devices: Early Experience From the COMPASS Registry.

Literature supports the need for improved techniques to achieve spinopelvic alignment and reduce complication rates in patients with adult spinal deformity (ASD). Personalized interbody devices were developed to address this need and are under evaluation in the multicenter Clinical Outcome Measures in Personalized aprevo (circle R superscript) Spine Surgery (COMPASS (TM suprascript) registry. This report presents interim COMPASS pre- and postoperative sagittal alignment results and complication rates for a subcohort of COMPASS patients diagnosed and surgically treated for spinal deformity. COMPASS is a postmarket observational registry of patients enrolled either before or after index surgery and then followed prospectively for 24 months. Sagittal alignment was assessed with SRS-Schwab modifiers for pelvic incidence minus lumbar lordosis, pelvic tilt, and T1 pelvic angle. Summed SRS-Schwab modifiers were utilized to assign overall deformity status as mild, moderate, or severe. Complications were extracted from patient medical records. The study included 67 patients from 9 centers. Preoperative severe deformity was observed in 66% of patients. Index surgeries included implantation of a median of 2 personalized interbody devices by anterior, lateral, or transforaminal approaches and with a median of 8 posteriorly instrumented levels. Overall postoperative sagittal alignment improved with a significant decrease in the mean sum of SRS-Schwab modifiers that correlated strongly to improvements in pelvic incidence minus lumbar lordosis. Among 44 patients with preoperative severe overall deformity, 16 improved to moderate and 9 to mild deformity. Complications occurred for 13 patients (19.4%), including 1 mechanical complication requiring revision 9 months after surgery and none related to personalized interbody devices. This study demonstrates that ASD patients whose treatment included personalized interbody devices can obtain favorable postoperative alignment status comparable to published results and with no complications related to the personalized interbody devices. This study contributes to growing evidence that personalized interbody devices contribute to improved sagittal alignment in ASD patients by directly adjusting the orientation of adjacent vertebra.

Correlations of spinopelvic parameters with quality of life of patients with adult degenerative scoliosis after posterior correction.

This study aimed to investigate the correlations of spinopelvic parameters with the quality of life of patients with adult degenerative scoliosis (ADS) after posterior correction, and their relationships with efficacy Patients and methods: Ninety patients (40 females, 50 males; mean age: 62.4±3.3 years; range, 47 to 73 years) with adult spinal deformity treated from March 2016 to May 2020 were retrospectively enrolled. The Scoliosis Research Society (SRS)-22 questionnaire was filled in by the patients, and the Oswestry disability index (ODI) and Visual Analog Scale (VAS) for back and lower limb pain were assessed. All the patients underwent posterior correction. Spearman's analysis was conducted for the correlations of the spinopelvic sagittal parameters with quality of life. The risk factors for efficacy were identified using the multivariate logistic regression model to construct a nomogram model for efficacy and risk prediction. After the operation, significant reductions were detected in the sagittal vertical axis (SVA), pelvic tilt (PT), T1 pelvic angle (TPA), pelvic incidence minus lumbar lordosis (PI-LL), and the ODI score (p<0.05). The SVA and LL were significantly negatively correlated with all subitems on the SRS-22 questionnaire but positively correlated with VAS scores for back pain (p<0.05). Thoracic kyphosis was significantly positively correlated with self-image and mental status on the SRS-22 questionnaire (p<0.05), while TPA was negatively correlated with pain and self-image (p<0.05). The PI-LL was significantly negatively correlated with pain (p<0.05). The SVA, LL, PT, and PI-LL were independent predictors of improvement in ODI after operation for ADS. The postoperative changes in spinopelvic parameters affected the clinical outcomes in patients with ADS.

Development and validation of an artificial intelligence model to accurately predict spinopelvic parameters.

Achieving appropriate spinopelvic alignment has been shown to be associated with improved clinical symptoms. However, measurement of spinopelvic radiographic parameters is time-intensive and interobserver reliability is a concern. Automated measurement tools have the promise of rapid and consistent measurements, but existing tools are still limited to some degree by manual user-entry requirements. This study presents a novel artificial intelligence (AI) tool called SpinePose that automatically predicts spinopelvic parameters with high accuracy without the need for manual entry. SpinePose was trained and validated on 761 sagittal whole-spine radiographs to predict the sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), T1 pelvic angle (T1PA), and L1 pelvic angle (L1PA). A separate test set of 40 radiographs was labeled by four reviewers, including fellowship-trained spine surgeons and a fellowship-trained radiologist with neuroradiology subspecialty certification. Median errors relative to the most senior reviewer were calculated to determine model accuracy on test images. Intraclass correlation coefficients (ICCs) were used to assess interrater reliability. SpinePose exhibited the following median (interquartile range) parameter errors: SVA 2.2 mm (2.3 mm) (p = 0.93), PT 1.3° (1.2°) (p = 0.48), SS 1.7° (2.2°) (p = 0.64), PI 2.2° (2.1°) (p = 0.24), LL 2.6° (4.0°) (p = 0.89), T1PA 1.1° (0.9°) (p = 0.42), and L1PA 1.4° (1.6°) (p = 0.49). Model predictions also exhibited excellent reliability at all parameters (ICC 0.91-1.0). SpinePose accurately predicted spinopelvic parameters with excellent reliability comparable to that of fellowship-trained spine surgeons and neuroradiologists. Utilization of predictive AI tools in spinal imaging can substantially aid in patient selection and surgical planning.

The Role of Pelvic Compensation in Sagittal Balance and Imbalance: The Impact of Pelvic Compensation on Spinal Alignment and Clinical Outcomes Following Adult Spinal Deformity Surgery.

The Scoliosis Research Society (SRS)-Schwab system does not include a pelvic compensation (PC) subtype, potentially contributing to gaps in clinical characteristics and treatment strategy for deformity correction. It also remains uncertain as to whether PC has differing roles in sagittal balance (SB) or imbalance (SI) status. To compare radiological parameters and SRS-22r domains between patients with failed pelvic compensation (FPC) and successful pelvic compensation (SPC) based on preoperative SB and SI. A total of 145 adult spinal deformity patients who received deformity correction were analyzed. Radiographic and clinical outcomes were collected for statistical analysis. Patients were classified into 4 groups based on the median value of PT/PI ratio (PTr) and the cutoff value of SB. Patients with low PTr and high PTr were defined as FPC and SPC, respectively. Radiographic and clinical characteristics of different groups were compared. Patients with SPC exhibited significantly greater improvements in lumbar lordosis, pelvic tilt, PTr, and T1 pelvic angle as compared to patients with FPC, irrespective of SB or SI. No apparent differences in any of SRS-22r domains were observed at follow-up when comparing the SB-FPC and SB-SPC patients. However, patients with SI-SPC exhibited significantly better function, self-image, satisfaction, and subtotal domains at follow-up relative to those with SI-FPC. When SI-FPC and SI-SPC patients were subdivided further based on the degree of PI-LL by adjusting for age, the postoperative function and self-image domains were significantly better in the group with overcorrection of PI-LL than undercorrection of PI-LL in SI-FPC patients. However, no differences in these SRS-22r scores were observed when comparing the subgroups in SI-SPC patients. Flexible pelvic rotation is associated with benefits to the correction of sagittal parameters, irrespective of preoperative SB or SI status. However, PC is only significantly associated with clinical outcomes under SI. Patients with SI-FPC exhibit poorer postoperative clinical outcomes, which should be recommended to minimize PI-LL.

Pre-contoured patient-specific rods result in superior immediate sagittal plane alignment than surgeon contoured rods in adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) surgery typically involves posterior spinal fusion (PSF) using rods contoured by the surgeon, which may be time-consuming and may not reliably restore optimal sagittal alignment. However, pre-contoured patient-specific rods may more optimally restore sagittal spinal alignment. This study evaluates the radiographic outcomes of AIS patients who underwent PSF utilizing surgeon contoured vs. pre-contoured rods. This is a retrospective cohort study of AIS patients who underwent PSF with either surgeon contoured or pre-contoured rods. Demographics, Lenke classification, fused levels, osteotomies, estimated blood loss (EBL), and surgical time were also obtained via chart review. Coronal curve magnitude, T5-T12 thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), PI-LL mismatch, and T1 pelvic angle (TPA) were obtained pre-operatively, postoperatively and at last follow up. Outcome measures included rate of achievement of postoperative radiographic alignment goals (TK between 20 and 40 degrees, PI-LL mismatch within 10 degrees, and TPA <14 degrees). Predicted post-operative sagittal alignment was also compared with observed measurements. Student's and paired t-tests were performed to determine significant mean differences for continuous variables, and chi-square for categorical variables. No differences were found in demographics, Lenke classification, preop radiographic measurements, fused levels, osteotomies, EBL, and surgical time in the surgeon contoured cohort (n=36; average follow up 11.3 months) and pre-contoured cohort (n=22; average follow up 9.7 months). At last follow up, 95.5% of patients with pre-contoured rods vs. 61.1% of patients with surgeon contoured rods (P=0.004) met TK goal. During assessment of first standing postoperative X-ray, 72.7% of patients with pre-contoured rods vs. 33.3% of patients with surgeon contoured rods met PI-LL mismatch goal (P=0.004). Other radiographic measurements were similar. Artificial intelligence (AI) predicted and observed differences for the pre-contoured group were 3.7 for TK (P=0.005), -7.6 for PI-LL mismatch (P=0.002), and -2.6 for TPA (P=0.11). AI and pre-contoured rods help achieve global sagittal balance with high accuracy and improved kyphosis restoration and PI-LL mismatch than surgeon contoured rods in AIS patients.

Comparison of multilevel low-grade techniques versus three-column osteotomies in adult spinal deformity surgery: does harmonious correction matter?

Recent debate has arisen between whether to use a three-column osteotomy (3CO) or multilevel low-grade (MLG) techniques to treat severe sagittal malalignment in adult spinal deformity (ASD) surgery. The goal of this study was to compare the outcomes of 3CO and MLG techniques performed in corrective surgeries for ASD. ASD patients who had a baseline PI-LL > 30° and 2-year follow-up data were included. Patients underwent either 3CO or MLG (thoracolumbar posterior column osteotomies at ≥ 3 levels or anterior lumbar interbody fusion at ≥ 3 levels with no 3CO). The segmental utility ratio was used to assess relative segmental correction (segmental correction divided by overall correction in lordosis divided by the number of thoracolumbar interventions [interbody fusion, thoracolumbar posterior column osteotomies, and 3CO]). The paired t-test was used to assess lordotic distribution by differences in lordosis between adjacent lumbar disc spaces (e.g., L1-2 to L2-3). Multivariate analysis, controlling for age, sex, BMI, osteoporosis, baseline pelvic incidence, and T1 pelvic angle, was used to evaluate the complication rates and radiographic and patient-reported outcomes between the groups. A total of 93 patients were included, 53% of whom underwent MLG and 47% of whom underwent 3CO. The MLG group had a lower BMI (p < 0.05). MLG patients received fewer previous fusions than 3CO patients (31% vs 80%, p < 0.001). MLG patients had 24% less blood loss but a 22% longer operative time (565 vs 419 minutes, p = 0.008). Using adjusted analysis, the 3CO group had greater segmental and relative correction at each level (segmental utility ratio mean 69% for 3CO vs 23% for MLG, p < 0.001). However, the 3CO group had lordotic differences between two adjacent lumbar disc pairs (range -0.5° to 9.0°, p = 0.009), while MLG was more harmonious (range 2.2°-6.5°, p > 0.4). MLG patients were more likely to undergo realignment to age-adjusted standards (OR 5.6, 95% CI 1.2-46.4; p = 0.033). MLG patients were less likely to develop neurological complications or undergo reoperation (OR 0.4, 95% CI 0.1-0.9; p = 0.041). Adjusted analysis revealed that MLG patients more often met a substantial clinical benefit in the Oswestry Disability Index score (OR 5.3, 95% CI 1.1-26.8; p = 0.043). MLG techniques showed better utility in lumbar distribution and age-adjusted global correction while minimizing neurological complications and reoperation rates by 2 years postoperatively. In selected instances, these techniques may offer the spine deformity surgeon a safer alternative when correcting severe adult spinal deformity.

Importance of the lumbar paraspinal muscles on the maintenance of global sagittal alignment after lumbar pedicle subtraction osteotomy.

There are limited data about the influence of the lumbar paraspinal muscles on the maintenance of sagittal alignment after pedicle subtraction osteotomy (PSO) and the risk factors for sagittal realignment failure. The authors aimed to investigate the influence of preoperative lumbar paraspinal muscle quality on the postoperative maintenance of sagittal alignment after lumbar PSO. Patients who underwent lumbar PSO with preoperative lumbar MRI and pre- and postoperative whole-spine radiography in the standing position were included. Spinopelvic measurements included pelvic incidence, sacral slope, pelvic tilt, L1-S1 lordosis, T4-12 thoracic kyphosis, spinosacral angle, C7-S1 sagittal vertical axis (SVA), T1 pelvic angle, and mismatch between pelvic incidence and L1-S1 lordosis. Validated custom software was used to calculate the percent fat infiltration (FI) of the psoas major, as well as the erector spinae and multifidus (MF). A multivariable linear mixed model was applied to further examine the association between MF FI and the postoperative progression of SVA over time, accounting for repeated measures over time that were adjusted for age, sex, BMI, and length of follow-up. Seventy-seven patients were recruited. The authors' results demonstrated significant correlations between MF FI and the maintenance of corrected sagittal alignment after PSO. After adjustment for the aforementioned parameters, the model showed that the MF FI was significantly associated with the postoperative progression of positive SVA over time. A 1% increase from the preoperatively assessed total MF FI was correlated with an increase of 0.92 mm in SVA postoperatively (95% CI 0.42-1.41, p < 0.0001). This study included a large patient cohort with midterm follow-up after PSO and emphasized the importance of the lumbar paraspinal muscles in the maintenance of sagittal alignment correction. Surgeons should assess the quality of the MF preoperatively in patients undergoing PSO to identify patients with severe FI, as they may be at higher risk for sagittal decompensation.

Evaluation of In-Brace Coronal and Sagittal Plane Measurements Between CAD/Chêneau-Style and Traditionally Fabricated Wilmington Braces in Adolescent Idiopathic Scoliosis

ABSTRACT Introduction Traditional thoracolumbosacral orthosis fabrication involves truncal casting (traditionally fabricated [TF] Wilmington brace [WB]), whereas the newer Chêneau-style brace (computer-aided design [CAD]) involves three-dimensional truncal scanning technology. We sought to evaluate how these two brace styles affect the position of the spine in the coronal and sagittal plane. Materials and Methods Inclusion criteria included adolescent idiopathic scoliosis treated with WB or CAD Chêneau-style brace, major curve Cobb angle 20°–45°, age 10–15 years, Risser 0–3, and radiographs (prebrace and in-brace posteroanterior and lateral). Analysis included 28 CAD Chêneau-style braces and 56 WB patients. Results There was no difference between groups regarding age, sex, body mass index, major curve location, major curve degree, sagittal plane curvature, and pelvic parameters. In-brace analysis demonstrated decreased sagittal plane curvatures and increased T1 pelvic angle in both groups; both had significantly reduced major curve correction. Coronal plane major curve correction ratio of the two groups was similar (P = 0.236). In the CAD Chêneau-style brace group, the thoracolumbar junction became more kyphotic (P = 0.03). In the WB group, both coronal balance and thoracic trunk shift were leftward (P = 0.001). Both groups had a significant increase in T1 pelvic angle, but this increase was higher in the CAD Chêneau-style brace group (P = 0.045). Conclusions Both braces exert a flattening effect on the spine and positive global sagittal balance. Coronal plane major curve correction was similar for both groups. Coronal plane trunk shift and C7 coronal balance were significantly changed leftward after WB application. Kyphotic thoracolumbar transition and forward tilt of the spine (T1 pelvic angle) were significantly greater in CAD Chêneau-style brace than WB. Clinical Relevance A Chêneau-style brace fabricated with CAD/computer-aided manufacturing technology can produce a brace comparable to one fabricated by traditional methods using cast molding.

Posterolateral Fusion Versus Posterior Lumbar Interbody Fusion for Adult Low-Grade Isthmic Spondylolisthesis: Analysis of Sagittal Radiographic Parameters - A Randomized Controlled Trial.

Randomized controlled trial. To compare the effect of posterolateral fusion (PLF) and posterior lumbar interbody fusion (PLIF) on sagittal radiographic parameters in patients with low-grade isthmic spondylolisthesis. Additionally, to explore the correlation between changes in these parameters and clinical outcomes. Forty-six consecutive patients with single-level low-grade isthmic spondylolisthesis were initially enrolled. They were randomly assigned to undergo either PLF or PLIF. Patients were followed up for at least 24 months. Radiographic outcomes included pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, sagittal vertical axis, T1 pelvic angle, slip angle, slip degree and disc height. Clinical outcomes were assessed by the Oswestry Disability Index (ODI) and visual analogue scale (VAS). Four participants were lost to follow-up. Of the remaining 42 patients, 29 were female. The mean age was 40.23 ± 10.25 years in the PLF group and 35.81 ± 10.58 years in the PLIF group. There was a statistically significant greater correction of all radiographic parameters in the PLIF group. The ODI and VAS improved significantly in both groups, with no significant differences between the two groups. Changes in the ODI and VAS were significantly correlated with changes in disc height, slip angle and lumbar lordosis. In patients with low-grade isthmic spondylolisthesis, PLIF demonstrates superior efficacy compared to PLF in correcting sagittal radiographic parameters. Nevertheless, this distinction does not seem to influence short-term clinical results. Restoring disc height, correcting the slip angle, and reestablishing normal lumbar lordosis are crucial steps in the surgical management of isthmic spondylolisthesis.

Artificial Intelligence Assistance for the Measurement of Full Alignment Parameters in Whole-Spine Lateral Radiographs

BackgroundMeasuring spinal alignment with radiological parameters is essential in patients with spinal conditions likely to be treated surgically. These evaluations are not usually included in the radiological report. As a result, spinal surgeons commonly perform the measurement, which is time-consuming and subject to errors. We aim to develop a fully automated artificial intelligence tool to assist in measuring alignment parameters in whole-spine lateral radiograph (WSL X-rays). Material and MethodsWe developed a tool called Vertebrai that automatically calculates the global spinal parameters (GSP): Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), L1-L4 angle, L4-S1 lumbo-pelvic angle, T1 pelvic angle (TPA), sagittal vertical axis (SVA), cervical lordosis (CL), C1-C2 lordosis, lumbar lordosis (LL), mid-thoracic kyphosis (MTK), proximal thoracic kyphosis (PTK), global thoracic kyphosis (GTK), T1 slope (T1S), C2-C7 plummet (cSVA), spino-sacral angle (SSA), C7 tilt (C7T), global tilt (GT), spinopelvic tilt (T1SPi) and hip odontoid axis (OD-HA). We assessed human-AI interaction instead of AI performance alone. We compared the time to measure GSP and inter-rater agreement with and without AI assistance. Two institutional datasets were created with 2267 multilabel images for classification, and 784 WSL X-rays with reference standard landmark labeled by spinal surgeons. ResultsVertebrai significantly reduced the measurement time comparing spine surgeons with AI assistance and the AI algorithm alone, without human intervention (3 minutes vs 0.26 minutes; p < 0.05). Vertebrai achieved an average accuracy of 83% in detecting abnormal alignment values, with the SS parameter exhibiting the lowest accuracy at 61.5% and T1SPi demonstrating the highest accuracy at 100%. Intra-class correlation analysis revealed a high level of correlation and consistency in the global alignment parameters. ConclusionsVertebrai's measurements can accurately detect alignment parameters, making it a promising tool for measuring GSP automatically.

Bone Quality as Measured by Hounsfield Units More Accurately Predicts Proximal Junctional Kyphosis than Vertebral Bone Quality Following Long-Segment Thoracolumbar Fusion

To compare the prognostic power of Hounsfield units (HU) and Vertebral Bone Quality (VBQ) score for predicting proximal junctional kyphosis (PJK) following long-segment thoracolumbar fusion to the upper thoracic spine (T1-T6). Vertebral bone quality around the upper instrumented vertebrae (UIV) was measured using HU on preoperative CT and VBQ on preoperative MRI. Spinopelvic parameters were also categorized according to the Scoliosis Research Society-Schwab classification. Univariable analysis to identify predictors of the occurrence of PJK and survival analyses with Kaplan-Meier method and Cox regression were performed to identify predictors of time to PJK (defined as ≥10° change in Cobb angle of UIV+2 and UIV). Sensitivity analyses showed thresholds of HU < 164 and VBQ > 2.7 to be most predictive for PJK. Seventy-six patients (mean age 66.0 ± 7.0 years; 27.6% male) were identified, of whom 15 suffered PJK. Significant predictors of PJK were high postoperative pelvic tilt (P= 0.038), high postoperative T1-pelvic angle (P= 0.041), and high postoperative PI-LL mismatch (P= 0.028). On survival analyses, bone quality, as assessed by the average HU of the UIV and UIV+1 was the only significant predictor of time to PJK (odds ratio [OR] 3.053; 95% CI 1.032-9.032; P= 0.044). VBQ measured using the UIV, UIV+1, UIV+2, and UIV-1 vertebrae approached, but did not reach significance (OR 2.913; 95% CI 0.797-10.646; P= 0.106). In larger cohorts, VBQ may prove to be a significant predictor of PJK following long-segment thoracolumbar fusion. However, Hounsfield units on CT have greater predictive power, suggesting preoperative workup for long-segment thoracolumbar fusion benefits from computed tomography versus magnetic resonance imaging alone to identify those at increased risk of PJK.