scholarly journals Sagittal alignment based on inflection point and its differences according to age groups

2020 ◽  
Vol 28 (1) ◽  
pp. 230949902090461
Author(s):  
Moon Soo Park ◽  
Seong-Hwan Moon ◽  
Tae-Hwan Kim ◽  
Jae Keun Oh ◽  
Seung Jin Lee ◽  
...  
Keyword(s):  
Pelvic Incidence ◽  
Sagittal Plane ◽  
Sagittal Alignment ◽  
Age Groups ◽  
Vertical Axis ◽  
Sacral Slope ◽  
Sagittal Vertical Axis ◽  
Inflection Points ◽  
Lumbar Segment ◽  
Cervical Segment

Purpose: We have always used the standard anatomical landmark vertebrae to measure the sagittal alignment. Instead, scoliosis has been evaluated by the end vertebrae in the coronal plane. There have been clinical studies to investigate sagittal alignment on the end vertebrae of inflection points (IPs). The purpose is to determine sagittal alignment based on IPs and to elucidate the changes while considering age groups. Methods: We identified the most titled vertebrae in the sagittal plane to define the end vertebrae of S1, thoracolumbar and cervicothoracic IPs and to measure the Cobb angles of sacral slope, functional lumbar, thoracic, cervical segment between them, and the McGregor’s line, and the IP distances from the C2 plumb line to the point bisecting the upper end plate of the IPs, in addition to S1. Results: The most common thoracolumbar and cervicothoracic IPs were L2 and T1, respectively. However, the next most common cervicothoracic IP changed from T2 in the youngest to C7 in the oldest age group. The sagittal angles decreased at the sacral slope and functional lumbar segment but not the functional thoracic segment and functional cervical segment. Similarly, the distance increased at the C2 sagittal vertical axis (SVA) distance to S1 and thoracolumbar IP distance but not at the cervicothoracic IP distance. There was no difference in the pelvic incidence among age groups. Conclusion: The sagittal Cobb angles based on the IPs decreased at the sacral slope and functional lumbar segment in the older adults. Consequently, the C2 SVA distance to S1 and thoracolumbar IP distance increased.

scholarly journals The Pelvic Incidence Stratified Sagittal Spinopelvic Alignment in Asymptomatic Chinese Population With Different Age Groups

2021 ◽  
pp. 219256822198964
Author(s):  
Siyu Zhou ◽  
Zhuoran Sun ◽  
Wei Li ◽  
Da Zou ◽  
Weishi Li
Keyword(s):  
Chinese Population ◽  
Pelvic Incidence ◽  
Sagittal Alignment ◽  
Age Groups ◽  
Vertical Axis ◽  
Elderly Subjects ◽  
Sagittal Vertical Axis ◽  
Cross Sectional ◽  
Sagittal Parameters ◽  
Very High

Study Design: Cross-sectional study. Objective: To provide the age- and pelvic incidence-related variations of sagittal alignment in asymptomatic Chinese population. Methods: This study recruited asymptomatic adult subjects. All subjects undertook the standing whole spinal radiograph and the sagittal parameters were measured: sagittal vertical axis (SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic incidence (PI) and pelvic tilt (PT). All subjects were divided into young, middle aged and elderly groups, then each age group was further divided into 5 subgroups (very low, low, average, high and very high) based on PI values. The relations between PI, age and other parameters were evaluated. The differences in sagittal parameters of each PI subgroup were compared. Results: 546 subjects were included with an average age of 38.6 years (18 to 81). The number of subjects over 70 years and with very low PI was relatively small. The average of PI, TPA, PT and LL were 45.9° ± 8.4°, 6.4° ± 6.2°, 11.9° ± 6.6° and 49.2° ± 10.1°, respectively. SVA, TPA, TK and PT increased with age ( P < 0.05), while SVA, TPA, PT, PI-LL also increased with PI ( P < 0.05). LL, PT, TPA, PI-LL and LL-TK were different among the 5 PI subgroups ( P < 0.05). However, the values of LL in elderly subjects with high and very high PI were similar. Conclusion: The age- and PI-related variations in sagittal alignment of Chinese population were provided. The sagittal parameters were significantly influenced by age and PI. The individual pelvic morphology should be carefully considered during the assessment and restoration of sagittal balance.

scholarly journals Sagittal profile modifications in hybrid versus all screw technique in adolescent idiopathic scoliosis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Laura Scaramuzzo ◽  
Antonino Zagra ◽  
Giuseppe Barone ◽  
Stefano Muzzi ◽  
Leone Minoia ◽  
...  
Keyword(s):  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Cobb Angle ◽  
Thoracic Kyphosis ◽  
Sagittal Alignment ◽  
Vertical Axis ◽  
Sagittal Profile ◽  
Sacral Slope ◽  
Sagittal Vertical Axis ◽  
Lenke Classification

AbstractAim of the study was to evaluate sagittal parameters modifications, with particular interest in thoracic kyphosis, in patients affected by adolescent idiopathic scoliosis (AIS) comparing hybrid and all-screws technique. From June 2010 to September 2018, 145 patients were enrolled. Evaluation included: Lenke classification, Risser scale, coronal Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS). Patients were divided in two groups (1 all-screws and 2 hybrid); a further division, in both groups, was done considering preoperative TK values. Descriptive and inferential statistical analysis was conducted. 99 patients were in group 1, 46 in group 2 (mean follow-up 3.7 years). Patients with a normo-kyphotic profile developed a little variation in TK (Δ pre–post = 2.4° versus − 2.0° respectively). Hyper-kyphotic subgroups had a tendency of restoring a good sagittal alignment. Hypo-kyphotic subgroups, patients treated with all-screw implants developed a higher increase in TK mean Cobb angle (Δ pre–post = 10°) than the hybrid subgroup (Δ pre–post = 5.4°) (p = 0.01). All-screws group showed better results in restoring sagittal alignment in all subgroups compared to hybrid groups, especially in hypo-TK subgroup, with the important advantage to give better correction on coronal plane.

scholarly journals Lumbar Level Significantly Influences Postoperative Global Sagittal Balance Following Pedicle Subtraction Osteotomy

2021 ◽  
pp. 219256822110325
Author(s):  
Athan G. Zavras ◽  
T. Barrett Sullivan ◽  
Navya Dandu ◽  
Howard S. An ◽  
Christopher J. DeWald ◽  
...  
Keyword(s):  
Sagittal Balance ◽  
Sagittal Alignment ◽  
Adult Spinal Deformity ◽  
Vertical Axis ◽  
Pedicle Subtraction Osteotomy ◽  
Current Evidence ◽  
Sacral Slope ◽  
Sagittal Vertical Axis ◽  
Lumbar Level ◽  
Global Sagittal Alignment

Study Design: Retrospective cohort study. Objectives: The current evidence regarding how level of lumbar pedicle subtraction osteotomy (PSO) influences correction of sagittal alignment is limited. This study sought to investigate the relationship of lumbar level and segmental angular change (SAC) of PSO with the magnitude of global sagittal alignment correction. Methods: This study retrospectively evaluated 53 consecutive patients with adult spinal deformity who underwent lumbar PSO at a single institution. Radiographs were evaluated to quantify the effect of PSO on lumbar lordosis (LL), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), T1-spinopelvic inclination (T1SPI), T1-pelvic alignment (TPA), and sagittal vertical axis (SVA). Results: Significant correlations were found between PSO SAC and the postoperative increase in LL ( r = 0.316, P = .021) and PT ( r = 0.352, P = .010), and a decrease in TPA ( r = −0.324, P = .018). PSO level significantly correlated with change in T1SPI ( r = −0.305, P = .026) and SVA ( r = −0.406, P = .002), with more caudal PSO corresponding to a greater correction in sagittal balance. On multivariate analysis, more caudal PSO level independently predicted a greater reduction in T1SPI (β = −3.138, P = .009) and SVA (β = −29.030, P = .001), while larger PSO SAC (β = −0.375, P = .045) and a greater number of fusion levels (β = −1.427, P = .036) predicted a greater reduction in TPA. Conclusion: This study identified a gain of approximately 3 degrees and 3 cm of correction for each level of PSO more caudal to L1. Additionally, a larger PSO SAC predicted greater improvement in TPA. While further investigation of these relationships is warranted, these findings may help guide preoperative PSO level selection.

scholarly journals Normal Age-Adjusted Sagittal Spinal Alignment Is Achieved with Surgical Correction in Adolescent Idiopathic Scoliosis

2017 ◽  
Vol 11 (5) ◽  
pp. 770-779 ◽  
Author(s):  
Subaraman Ramchandran ◽  
Norah Foster ◽  
Akhila Sure ◽  
Thomas J. Errico ◽  
Aaron J. Buckland
Keyword(s):  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Lumbar Lordosis ◽  
Thoracic Kyphosis ◽  
Pelvic Incidence ◽  
Sagittal Alignment ◽  
Vertical Axis ◽  
Surgical Correction ◽  
Sagittal Vertical Axis

<sec><title>Study Design</title><p>Retrospective analysis.</p></sec><sec><title>Purpose</title><p>Our hypothesis is that the surgical correction of adolescent idiopathic scoliosis (AIS) maintains normal sagittal alignment as compared to age-matched normative adolescent population.</p></sec><sec><title>Overview of Literature</title><p>Sagittal spino-pelvic alignment in AIS has been reported, however, whether corrective spinal fusion surgery re-establishes normal alignment remains unverified.</p></sec><sec><title>Methods</title><p>Sagittal profiles and spino-pelvic parameters of thirty-eight postsurgical correction AIS patients ≤21 years old without prior fusion from a single institution database were compared to previously published normative age-matched data. Coronal and sagittal measurements including structural coronal Cobb angle, pelvic incidence, pelvic tilt, thoracic kyphosis, lumbar lordosis, sagittal vertical axis, C2–C7 cervical lordosis, C2–C7 sagittal vertical axis, and T1 pelvic angles were measured on standing full-body stereoradiographs using validated software to compare preoperative and 6 months postoperative changes with previously published adolescent norms. A sub-group analysis of patients with type 1 Lenke curves was performed comparing preoperative to postoperative alignment and also comparing this with previously published normative values.</p></sec><sec><title>Results</title><p>The mean coronal curve of the 38 AIS patients (mean age, 16±2.2 years; 76.3% female) was corrected from 53.6° to 9.6° (80.9%, <italic>p</italic>&lt;0.01). None of the thoracic and spino-pelvic sagittal parameters changed significantly after surgery in previously hypo- and normo-kyphotic patients. In hyper-kyphotic patients, thoracic kyphosis decreased (<italic>p</italic>=0.003) with a reciprocal decrease in lumbar lordosis (<italic>p</italic>=0.01), thus lowering pelvic incidence-lumbar lordosis mismatch mismatch (<italic>p</italic>=0.009). Structural thoracic scoliosis patients had slightly more thoracic kyphosis than age-matched patients at baseline and surgical correction of the coronal plane of their scoliosis preserved normal sagittal alignment postoperatively. A sub-analysis of Lenke curve type 1 patients (n=24) demonstrated no statistically significant changes in the sagittal alignment postoperatively despite adequate coronal correction.</p></sec><sec><title>Conclusions</title><p>Surgical correction of the coronal plane in AIS patients preserves sagittal and spino-pelvic alignment as compared to age-matched asymptomatic adolescents.</p></sec>

scholarly journals Spinal sagittal alignment and head control in patients with cerebral palsy

2020 ◽  
Vol 14 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Brice Ilharreborde ◽  
Adrien de Saint Etienne ◽  
Ana Presedo ◽  
Anne-Laure Simon
Keyword(s):  
Cerebral Palsy ◽  
Sagittal Alignment ◽  
Vertical Axis ◽  
Sacral Slope ◽  
Trunk Control ◽  
Level Of Evidence ◽  
Sagittal Vertical Axis ◽  
Spinal Sagittal Alignment ◽  
Trunk Posture ◽  
Radiological Analysis

Purpose Spinal sagittal alignment restoration has been associated with improved functional outcomes and with reduced complications rates. Several limitations exist for radiological analysis in cerebral palsy (CP) patients. The goal of this study was to summarize the existing literature and report the important considerations to evaluate in a CP patient undergoing spinal surgery. Methods A retrospective radiological analysis was performed, including non-ambulant CP children with progressive scoliosis. Full-spine sitting radiographs performed pre-and postoperatively were required to measure spino-pelvic sagittal parameters. Result A total of 23 non-ambulating CP patients were included, mean age 16.0 years (standard error of the mean 0.5). Two distinct groups of patients were identified. Group 1 (61%) were patients with less trunk control (lumbar lordosis (LL) < 50°), retroverted and vertical pelvis (mean sacral slope (SS) 11.4° and pelvic tilt (PT) 38.1°) and anterior imbalance (mean sagittal vertical axis (SVA) 5.9 cm) and Group 2 (39%) were patients with better trunk control (LL > 60°, anteverted and horizontal pelvis (mean SS 49.3°, PT 9.7°) and posterior imbalance (mean SVA 5.8 cm). Postoperative measures showed significant impact of surgery with a PT reduction of 19° (p = 0.007), a mean SS increase of 15° (p = 0.04) and a LL gained of 10° (p = 0.2). Conclusion Sagittal spino-pelvic alignment in non-ambulating CP patients remains difficult to assess. The current literature is poor but our radiological study was able to define two distinct groups among Gross Motor Function Classification System (GMFCS) level V patients, based on the quality of their trunk control. All possible factors that may influence head and trunk posture should be systematically considered and optimized. Level of evidence Level IV

scholarly journals Long-term effects of the Chêneau brace on coronal and sagittal alignment in adolescent idiopathic scoliosis

2015 ◽  
Vol 23 (4) ◽  
pp. 505-509 ◽  
Author(s):  
Ming-Qiao Fang ◽  
Chong Wang ◽  
Guang-Heng Xiang ◽  
Chao Lou ◽  
Nai-Feng Tian ◽  
...  
Keyword(s):  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Sagittal Alignment ◽  
Vertical Axis ◽  
Sacral Slope ◽  
Long Term Effects ◽  
Sagittal Vertical Axis ◽  
Pelvic Parameters

OBJECT The aim of the present study was to retrospectively evaluate progressive correction of coronal and sagittal alignment and pelvic parameters in patients treated with a Chêneau brace. METHODS Thirty-two patients with adolescent idiopathic scoliosis (AIS) were assessed before initiation of bracing treatment and at the final follow-up. Each patient underwent radiological examinations, and coronal, sagittal, and pelvic parameters were measured. RESULTS No statistically significant modification of the Cobb angle was noted. The pelvic incidence remained unchanged in 59% of the cases and increased in 28% of the cases. The sacral slope decreased in 34% of the cases but remained unchanged in 50%. Thoracic kyphosis and lumbar lordosis were significantly decreased, whereas the sagittal vertical axis was significantly increased from a mean of -44.0 to -30.2 mm (p = 0.02). The mean pelvic tilt increased significantly from 4.5° to 8.3° (p = 0.002). CONCLUSIONS The Chêneau brace can be useful for preventing curvature progression in patients with AIS. However, the results of this study reveal high variability in the effect of brace treatment on sagittal and pelvic alignment. Treatment with the Chêneau brace may also influence sagittal global balance.

scholarly journals Increasing pelvic incidence is associated with more global sagittal imbalance in ankylosing spondylitis with thoracolumbar kyphosis

2019 ◽  
Author(s):  
Diyu Song ◽  
Guoquan Zheng ◽  
Tianhao Wang ◽  
Dengbin Qi ◽  
Yan Wang
Keyword(s):  
Ankylosing Spondylitis ◽  
Pelvic Incidence ◽  
Vertical Axis ◽  
Control Group ◽  
Sacral Slope ◽  
Sagittal Imbalance ◽  
Thoracolumbar Kyphosis ◽  
Spinopelvic Parameters ◽  
Sagittal Vertical Axis ◽  
The Relationship

Abstract Background: Ankylosing spondylitis (AS) patients with kyphosis have an abnormal spinopelvic alignment and pelvic morphology. Most of them focus on the relationship of pelvic tilt (PT) or sacral slope (SS) and deformity, and relatively few studies have addressed the relationship between pelvic incidence (PI) and kyphosis in AS patients. The purpose of this study is to analyze the correlation between pelvic incidence (PI) and the spinopelvic parameters describing local deformity or global sagittal balance in AS patients with thoracolumbar kyphosis. Methods: A total of 94 patients with AS (91 males and 3 females) and 30 controls were reviewed. Sagittal spinopelvic parameters, including PI, PT, SS, thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis(LL), sagittal vertical axis(SVA), T1 pelvic angle(TPA), spinosacral angle(SSA) and spinopelvic angle(SPA) were measured. Statistical analysis was performed to identify the correlation of PI with other parameters. Results: Compared with the control group, the AS patients had significantly higher PI(47.4˚ vs. 43.2˚, P<0.001). PI in AS patients was found to be significantly positively correlated with TPA(r=0.533, R 2 =0.284, P<0.001), and negatively correlated with SPA(r=-0.504, R 2 =0.254, P<0.001). However, no correlations were found between PI and SVA, SSA, TK, TLK or LL in AS patients. Conclusion: The value of PI in AS patients with kyphosis was significantly higher than that of controls. Correlation analysis revealed that increasing PI was significantly correlated with more global sagittal imbalance, not with the local deformity in AS patients with thoracolumbar kyphosis.

scholarly journals Effect of sagittal imbalance on functional disability in patients with degenerative spondylolisthesis

2019 ◽  
Vol 6 (1) ◽  
pp. 31
Author(s):  
Ramdas Maloth
Keyword(s):  
Functional Disability ◽  
Pelvic Incidence ◽  
Sagittal Plane ◽  
Degenerative Spondylolisthesis ◽  
Vertical Axis ◽  
P Value ◽  
Sagittal Imbalance ◽  
Sagittal Vertical Axis ◽  
Cross Sectional ◽  
Digital Radiograph

<p class="abstract"><strong>Background:</strong> Deformity of spine in sagittal plane is a major cause of pain and disability among patients presenting with low back pain to spine clinic. We have studied the effect of spinal sagittal imbalance on functional disability in these patients.</p><p class="abstract"><strong>Methods:</strong> Cross sectional observational study in 50 patients with degenerative spondylolisthesis of more than 45 years age group study done in period of1 years. Subjects underwent standing lateral radiographs of the spine in a relaxed position, facing forward, with their knees maximally extended and their arms raised horizontally forward resting on a support. 2 radiographic films are stitched at baseline using digital radiograph operating console (DROC) software.</p><p class="abstract"><strong>Results: </strong>In our study out of 50 patients we observed female preponderance, female:male 3:1, degenerative spondylolisthesis more commonly involves L4-L5 level (46 patients). 58% of patients with severe degenerative spondylolisthesis. There is significant correlation between sagittal vertical axis (SVA) and severity (p=0.015) in both grade 1 and grade 2 DS, there is significant correlation between pi and functional disability (p=0.001 and 0.010 respectively) it is found that pelvic tilt with p=0.02 and sagittal vertical axis with p value 0.036 are the two most significant variables at the end of backward elimination analysis.</p><p class="abstract"><strong>Conclusions:</strong> Sagittal imbalance is seen in degenerative spondylolisthesis which needs further evaluation with spinopelvic parameters. Pelvic incidence and sagittal vertebral axis are important determinants of functional disability in patients with degenerative spondylolisthesis. Individuals with high pelvic incidence and more lumbo pelvic kyphosis showed more functional disability compared to others.</p>

scholarly journals Improvement in cervical lordosis and sagittal alignment after vertebral body sliding osteotomy in patients with cervical spondylotic myelopathy and kyphosis

2020 ◽  
Vol 33 (3) ◽  
pp. 307-315 ◽  
Author(s):  
Dong-Ho Lee ◽  
Choon Sung Lee ◽  
Chang Ju Hwang ◽  
Jae Hwan Cho ◽  
Jae-Woo Park ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Cervical Spondylotic Myelopathy ◽  
Sagittal Alignment ◽  
Japanese Orthopaedic Association ◽  
Vertical Axis ◽  
Sacral Slope ◽  
Cervical Lordosis ◽  
Sagittal Vertical Axis ◽  
Segmental Lordosis

OBJECTIVEVertebral body sliding osteotomy (VBSO) is a safe, novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. Another advantage of VBSO may be the restoration of cervical lordosis through multilevel anterior cervical discectomy and fusion (ACDF) above and below the osteotomy level. This study aimed to evaluate the improvement and maintenance of cervical lordosis and sagittal alignment after VBSO.METHODSA total of 65 patients were included; 34 patients had undergone VBSO, and 31 had undergone anterior cervical corpectomy and fusion (ACCF). Preoperative, postoperative, and final follow-up radiographs were used to evaluate the improvements in cervical lordosis and sagittal alignment after VBSO. C0–2 lordosis, C2–7 lordosis, segmental lordosis, C2–7 sagittal vertical axis (SVA), T1 slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and Japanese Orthopaedic Association scores were measured. Subgroup analysis was performed between 15 patients with 1-level VBSO and 19 patients with 2-level VBSO. Patients with 1-level VBSO were compared to patients who had undergone 1-level ACCF.RESULTSC0–2 lordosis (41.3° ± 7.1°), C2–7 lordosis (7.1° ± 12.8°), segmental lordosis (3.1° ± 9.2°), and C2–7 SVA (21.5 ± 11.7 mm) showed significant improvements at the final follow-up (39.3° ± 7.2°, 13° ± 9.9°, 15.2° ± 8.5°, and 18.4 ± 7.9 mm, respectively) after VBSO (p = 0.049, p < 0.001, p < 0.001, and p = 0.038, respectively). The postoperative segmental lordosis was significantly larger in 2-level VBSO (18.8° ± 11.6°) than 1-level VBSO (10.3° ± 5.5°, p = 0.014). The final segmental lordosis was larger in the 1-level VBSO (12.5° ± 6.2°) than the 1-level ACCF (7.2° ± 7.6°, p = 0.023). Segmental lordosis increased postoperatively (p < 0.001) and was maintained until the final follow-up (p = 0.062) after VBSO. However, the postoperatively improved segmental lordosis (p < 0.001) decreased at the final follow-up (p = 0.045) after ACCF.CONCLUSIONSNot only C2–7 lordosis and segmental lordosis, but also C0–2 lordosis and C2–7 SVA improved at the final follow-up after VBSO. VBSO improves segmental cervical lordosis markedly through multiple ACDFs above and below the VBSO level, and a preserved vertebral body may provide more structural support.

scholarly journals The impact of spinopelvic morphology on the short-term outcome of pedicle subtraction osteotomy in 104 patients

2017 ◽  
Vol 27 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Karin Eskilsson ◽  
Deep Sharma ◽  
Christer Johansson ◽  
Rune Hedlund
Keyword(s):  
Clinical Outcome ◽  
Sagittal Plane ◽  
Vertical Axis ◽  
Pedicle Subtraction Osteotomy ◽  
Sacral Slope ◽  
Sagittal Imbalance ◽  
Sagittal Vertical Axis ◽  
Term Outcome ◽  
Pelvic Morphology ◽  
The Impact

OBJECTIVEPedicle subtraction osteotomy (PSO) is commonly performed for correction of spinal sagittal plane deformities. The PSO results in complex, multiple changes of the spinopelvic alignment. The influence of the variability of individual pelvic morphology has not been fully analyzed in previous outcome studies of sagittal imbalance. The aim of this study was to define radiological variables affecting the outcome after PSO in adult spinal deformities, with special emphasis on the variability of pelvic morphology.METHODSClinical and radiographic outcomes were analyzed in a retrospective analysis of 104 patients who underwent a PSO at a single center. The radiographic variables studied were sagittal vertical axis (SVA), T1SPI (T-1 spinopelvic inclination), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). To control for the individual variation of pelvic morphology, the LL/PI, PT/PI, and SS/PI ratios were calculated. Clinical outcome was assessed using the visual analog scale for pain, Oswestry Disability Index, and EQ-5D preoperatively and at a minimum 1-year follow-up. Correlation coefficients were calculated between each individual radiographic variable and the outcome measures. The importance of LL mismatch to TK, reflecting the importance of a harmonious spine, was analyzed by comparing the outcome of patients with a TK+LL+PI ≤ 45° to those with a sum > 45°.RESULTSSVA and T1SPI demonstrated the strongest correlation with the clinical outcome scores (r = 0.4–0.5, p < 0.001). LL correlated weakly with the clinical outcome (r = 0.2–0.3, p < 0.003). Mismatch of LL to PI, however, did not correlate significantly with the outcome. Similarly, only weak and inconsistent correlation was observed between PT, SS, PT/PI, SS/PI, and functional outcome. Patients with a TK+LL+PI ≤ 45° had a significantly lower ODI score (33 vs 44) and a significantly higher EQ-5D score (0.64 vs 0.40) than patients with a sum > 45° (LL is a negative value).CONCLUSIONSPSO resulted in a substantial correction of sagittal imbalance and improved outcome in most patients in this study. Correction of the global sagittal balance appears to be a necessary precondition for a good outcome. A harmonious spine with a TK and an LL of similar magnitude seems to add to a positive outcome.

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