Sagittal Imbalance In Patients Research Articles

Sagittal Imbalance in Degenerative Kyphosis: Prevalence and Implication on Postoperative Mechanical Failure

BACKGROUND AND OBJECTIVES: To explore the patterns of sagittal imbalance in patients with lumbar or thoracolumbar degenerative kyphosis (DK) and determine its implication for the risk of mechanical complication (MC) after corrective surgery. METHODS: A total of 137 patients with DK who underwent corrective surgery were reviewed. The patients were divided into L group (with a kyphotic apex at L2 and below) and TL group (with kyphotic apex at L1 and above). Then, sacral slope (SS) (defined as S1 if SS > 0 in TL, or SS > 10 in L group) and sagittal vertical axis ≥ 5 cm (defined as +) were used as modifier sagittal balance. The Scoliosis Research Society (SRS)-22 questionnaire scores were analyzed, and the risk of mechanical failure was compared across groups. RESULTS: The distribution of subgroups was 38 (27.7%) in TLS1(−) group, 36 (26.3%) in TLS1(+) group, 16 (11.7%) in TLS0(−) group, and 5 (3.6%) in TLS0(+) group. For L group, the figure was 5 (3.6%) in LS1(−), 22 (16.1%) in LS1(+), 7 (5.2%) in LS0(−), and 8 (5.8%) in LS0(+). Patients in L group had significantly higher regional kyphosis, lower lumbar lordosis, and higher sagittal vertical axis, indicating a higher risk of global decompensation. The SRS function scores and pain scores were also lower in the L group compared with the TL group. At a minimum of 2 years of follow-up, χ2 test showed that the incidence of TLS0 (+), LS0 (−), and LS0 (+) had significantly higher rates of MC (>40%). In both TL and L groups, patients with MC were found to have significantly lower bone mineral density than those without. CONCLUSION: The findings decipher the distinct patterns of sagittal imbalance in severe DK patients with kyphotic apex at thoracolumbar or lumbar spine. Patients with kyphotic apex apex at L2 or below, low SS, and global imbalance showed the highest risk of postoperative mechanical failure.

FREQUENCY OF SAGITTAL IMBALANCE IN PATIENTS WITH IDIOPATHIC ADOLESCENT SCOLIOSIS

Objective: To determine the frequency of sagittal imbalance in patients with idiopathic adolescent scoliosis Materials and Methods: This Cross-sectional study was conducted in the Department of Orthopedic Surgery, Khyber Teaching Hospital, Peshawar from 20 May 2019 to 19 Nov 2019 on 88 patients by Consecutive probability sampling technique. A standard technique was used for the study radiograph. Data was stored and analyzed using the statistical software SPSS version 21. All the quantitative variables like age were analyzed by Mean, +/- standard deviation. Post-stratification chi-square test was applied keeping P value equal or less than 0.05. All the results were presented in tables and graphs. RESULTS: A total of 88 patients with adolescent idiopathic scoliosis were enrolled in this study. There were 22 male (25%) and 66 (75%) female patients. The mean age of patients received was 43 years +/- 13.4 years with a standard deviation of +/-0.23. Regarding deformity severity, there was mild deformity (Cobb angle 10-25) in 33, patients (37.5%), moderate deformity (Cobb angle 26-40) in 26 patients (29.5%) moderately severe deformity (Cobb angle41-60) in 18 (20.5%) severe deformity (>60) in 11 (12.5%). Fifty-six (63.6%) patients had structural curves i.e. flexible and corrected with the forward Adam bending test. Thirty-two (36.4%) had a nonstructural or rigid deformity. CONCLUSION: Most of the patients having adolescent idiopathic scoliosis have a sagittal imbalanced spine. Spinopelvic parameters like lumbar lordosis, sacral slope, pelvic incidence, and pelvic tilt need to be included in routine workups of scoliotic patients in specific groups like one with a rigid deformity, severe deformity, and advancing age. Spinopelvic imbalance is very important in adult deformity. KEY WORDS: Adolescent Idiopathic scoliosis AIS, Sagittal Imbalance, Spinopelvic imbalance.

The Effect of Laminectomy with Instrumented Fusion Carried into the Thoracic Spine on the Sagittal Imbalance in Patients with Multilevel Ossification of the Posterior Longitudinal Ligament.

ObjectiveTo determine if there is a difference in either the cervical alignment or the clinical outcomes in cervical ossification of the posterior longitudinal ligament (OPLL) patients who underwent laminectomy with instrumented fusion (LIF) ending at C6, C7, or proximal thoracic spine for the treatment of multilevel OPLL, and to find out the appropriate distal fusion level.MethodsThis was a single‐center retrospective study. In total, 36 patients with cervical OPLL who underwent three or more level LIF in our institution between January 2015 and January 2017 were enrolled. They were divided into three groups according to their distal ends: C6 (nine females and 11 males, 60.45 ± 9.68 years old), C7 (four females and six males, 61.60 ± 10.29 years old), and T‐group (two females and four males, 64.33 ± 8.12 years old). Radiographic (compression level, classification of OPLL, occupying rate, C2‐7 cobb angle, C2‐7 sagittal vertical axis, and fusion level) and clinical outcomes (NDI score, operative time, and blood loss) were compared. Predictors of postoperative sagittal imbalance were also identified according to if the postoperative C2‐7 SVA was greater than 40 mm. The sensitivity and specificity of preoperative parameters predicting postoperative cervical stability were evaluated via the receiver operating characteristic (ROC) curve.ResultsAll patients were followed up at least 1 year. The blood loss in T group was significantly more than C6 or C7 group. The length of fusion level became significantly longer when the caudal level extended to the thoracic spine. The age, preoperative SVA, and NDI score at follow‐up were significantly greater in the imbalance group. At the final follow‐up, the cervical lordosis tended to be straight and the C2‐7 SVA tended to be greater when the caudal level of fusion was extended to upper thoracic segment. Further ROC curve analysis suggested that patients’ age had a sensitivity of 75.00%, specificity of 79.17% for cervical stability, and the AUC was 0.844 (P < 0.01), with the cutoff value for age being 66.5 years old. For preoperative SVA, the sensitivity was 58.30%, and specificity was 91.70%, with the AUC of 0.778 (P < 0.01). The cutoff value for preoperative SVA was 30.4 mm.ConclusionAlthough posterior fusion terminating in the thoracic spine was not superior to the cervical spine for patients with multilevel OPLL, for elderly patients (>67 years) with great preoperative SVA (>30 mm), terminating at C6 was recommended to limit the invasion of cervical extensor muscles, provided the decompression was adequate.

Optimal Lumbar Lordosis Correction for Adult Spinal Deformity with Severe Sagittal Imbalance in Patients Over Age 60: Role of Pelvic Tilt and Pelvic Tilt Ratio.

Study Design.A retrospective study.Objectives.The purpose of this study was to evaluate optimal and ideal target values of the spine balance correction in elderly patients with adult spinal deformity who were over the age of 60 years.Summary of Background Data.The target values of the Scoliosis Research Society -Schwab classification to obtain satisfactory alignment and favorable outcomes are used in many spinal reconstruction surgeries. However, uniformly applying the Scoliosis Research Society-Schwab classification to all elderly patients aged 60 years or older showing sagittal malalignment may lead to several inconsistencies.Methods.This study included 121 patients (average age 70.5 yr and a minimum 2-yr follow-up) with adult spinal deformity who underwent long-segment fusion from T10 to sacrum. We used Pearson's correlation coefficient to analyze the relationship between clinical and radiographic parameters, and multilinear regression analysis and multivariate logistic regression model (backward elimination method) were conducted using the correlation factors of postoperative (Post) and last follow-up (Last) sagittal vertical axis to find the risk factors of Post sagittal imbalance.Results.Logistic regression analysis with the correlation factors of Post and Last sagittal vertical axis led to risk factors of Post sagittal imbalance, and after confirming the significance of each path, it was confirmed that the effects of pelvic incidence (PI)— lumbar lordosis (LL) and Post pelvic tilt ratio (PTr) were valid (P < 0.05). After using ROC curve, target value of PI-LL was 1.33, and that of PTr was 25.95%.Conclusion.Through our study, the risk factors of Post sagittal imbalance were the Post value of PI-LL and that of PTr, and target value of PI-LL was <1.33 and that of PTr was <25.95%. These target values can be effective guidelines for spine surgeons who perform spine reconstruction surgeries for elderly patients with a pure sagittal imbalance based on Schwab's formula.Level of Evidence: 4

Sagittal imbalance of the spine-pelvis-lower extremity axis associated with back-related disability

BackgroundThe impact of sagittal imbalance in patients has been reported in LBP and LBP-related disabilities due to spinopelvic imbalance. However, no reports investigating the spine-pelvis-lower extremity axis using lateral images have been reported thus far. This study introduced a novel parameter of the spine-pelvis-lower extremity axis and evaluated whether this parameter was related to symptoms. MethodsA total of 343 subjects were included in this cross-sectional study. Standing spine-pelvis and pelvis-lower extremity radiographs were obtained to assess the sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis, and thoracic kyphosis. The sacral-knee distance (SKD) (i.e., distance from the anterior femoral condyle to the vertical axis at the upper posterior edge of S1 body) was measured. Furthermore, the SVA/SKD ratio was calculated for global balance. Subjects were divided into leg compensated (LC; SVA/SKD ratio <0.8) and decompensated (LD; SVA/SKD ratio ≥0.8) groups. The SVA was divided into balanced spine (BS; SVA ≤40 mm) and imbalanced spine (IS; SVA >40 mm) groups. All individuals were classified into LC + BS, LC + IS, LD + BS, and LD + IS groups. The relationships among the four groups and low back pain (LBP), Oswestry Disability Index (ODI), and knee pain were examined. ResultsSKD was significantly correlated with SVA, SS, PI, PT, and knee-femoral angle. ODI was significantly higher in the LC + IS group than in the LD + BS group (p < 0.05). Knee pain prevalence was significantly higher in the LC + IS and LC + BS groups than in the LD + IS group (p < 0.05). ConclusionSVA/SKD ratio is useful for evaluating global alignment. Our findings are significant because they highlight the importance of SKD with respect to knee pain, LBP, and LBP- related disabilities.

Improvement in Gait Pattern and its Relationship With Preoperative Pelvic Compensation After Surgery in Patients With Sagittal Plane Deformity.

Prospective observational study. The aim of this study was to investigate the improvement in gait parameters after surgery and whether corrective surgery for sagittal imbalance would be influenced by preoperative pelvic compensation. There have been no other studies investigating the influence of preoperative pelvic compensation on surgical outcomes. A total of 32 patients who were scheduled to undergo corrective surgery for sagittal plane deformity were included and were followed-up for 1 year after surgery. Radiological parameters were measured on biplanar full-body imaging. Before surgery and 6 months after surgery, three-dimensional motion analyses were performed to estimate center of gravity (CoG) deviation from the center of mass (CoM), mean trunk kyphosis (TK) angle, gait deviation index (GDI), and kinematic parameters. Before surgery, the patients were classified into CoG+ and CoG- groups. "+" and "-" representing increases and decreases in the distance of CoG from CoM of the pelvic segment from first to third trials, respectively. Oswestry Disability Index (ODI) and EuroQol-5D (EQ-5D) were measured for 1 year after surgery. All radiological parameters improved significantly after surgery. For gait parameters, CoG from CoM, mean TK angle, and minimum angle of the hip and knee joints in the stance phase during walking were significantly decreased after surgery and GDI scores significantly improved after surgery. The mean changes of the CoG distance from the CoG and the mean TK from first to third trials of gait analysis significantly decreased postoperatively. There were no significant differences in ODI and EQ-5D scores over 1-year follow-up assessment between CoG+ and CoG- groups. Preoperative abnormal stooping gait, and progressive worsening of sagittal imbalance in patients with sagittal plane deformity improved after corrective surgery. Patients with preoperative dynamic sagittal imbalance could have similar surgical results to those without it after corrective surgery. 3.

232. Optimal lumbar lordosis correction for adult spinal deformity with severe sagittal imbalance in patients over age 65: role of pelvic tilt and pelvic tilt ratio

BACKGROUND CONTEXT The prevalence of adult spinal deformity (ASD) is increasing as the average age of the population increases. Optimal surgical correction for patients with ASD is necessary. The Scoliosis Research Society-Schwab classification is used for optimal surgical correction in many spinal reconstruction surgeries, and the targets to obtain satisfactory alignment and favorable outcomes are ≤10° for pelvic incidence (PI) minus lumbar lordosis (LL), 20°, while pathologic based on Schwab criteria, may be a natural phenomenon in patients with a large PI. Therefore, the concept of global tilt has been introduced recently, and to overcome the limitations of PT in our study, a PT ratio value (PTr) of PT/PI x 100% was calculated along with measurement of PT. PURPOSE The purpose of this study was to evaluate optimal and ideal target values including PTr of the spine balance correction in elderly patients with ASD who were over the age of 65 years. STUDY DESIGN/SETTING Retrospective, consecutive case review. PATIENT SAMPLE A total of 121 patients (average age 70.5 years and a minimum 2-year follow up) with lumbar degenerative kyphosis (LDK) who underwent long-segment fusion from T10 to sacrum. OUTCOME MEASURES Description and analysis of x-ray changes. METHODS Based on the correction angle of their LL and incorporating PI, the patients were divided into 5 groups using the Schwab classification. Clinical and radiologic parameters were analyzed: Group 1 was 10 RESULTS The groups that showed 80% or more optimal sagittal alignment at their postoperative (Post) and the last follow-up (Last), were group 3, 4, and 5. Post and Last thoracic kyphosis (TK) were increased naturally. Post PT was decreased, but group 1 and 2 did not meet Schwab's target value, and the Post and Last PTr showed a tendency to decrease from group 1 to group 5 as LL increased. Based on correlation test with Post SVA, TK correction and SVA correction, Post lumbosacral angle, Post LL, PI–LL, Post PTr and Post PT were associated. Logistic regression analysis with these correlation factors led to risk factors of Post sagittal imbalance, and after confirming the significance of each path, it was confirmed that the effects of PI–LL and Post PTr were valid (p CONCLUSIONS Our study showed that undercorrection showed unfavorable results for the correction of LDK patients over age 65. Therefore, the restoration of global sagittal balance is more important, and through our study, the risk factors of Post sagittal imbalance were the value of PI–LL and that of PTr, and target value of PI-LL was FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Impact of pedicle subtraction osteotomy on health-related quality of life (HRQOL) measures in patients undergoing surgery for adult spinal deformity: a systematic review and meta-analysis.

Systematic review and meta-analysis. Three-column osteotomies (3-CO) have gained popularity in the last decade as part of the armamentarium for the surgical correction of sagittal imbalance in patients with adult spinal deformity (ASD). Three-column osteotomies in the form of pedicle subtraction osteotomy (PSO) may be necessary to achieve adequate correction for severe and rigid spinal deformity. Studies reporting improvement in health-related quality of life (HRQOL) with validated outcome measures after PSO surgery are sparse and currently consist of small series. Evaluate the improvement in HRQOL measures following PSO for adult spinal deformity. Two independent reviewers conducted a systematic review of the English literature between period 1996 and 2019 for articles reporting outcome of PSO in patients with ASD according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Inclusion criteria were studies consisting of patient-reported outcome Oswestry Disability Index (ODI) and Scoliosis Research Society 22 or 24 (SRS) outcomes after PSO surgery for adult spine deformity patients (18years or older) with a minimum follow-up of 1year. Eight studies with 431 PSOs were included in the meta-analysis. The results showed a statistically significant improvement in ODI in PSO (P < 0.0001), and the mean clinically important difference was achieved with both ODI (50.46 (45.5-55.4) preoperatively to 32.78 (29.7-39) postoperatively) and SRS (2.49 (2.38-2.7) preoperatively to 3.26 (2.8-4.1) postoperatively) scores. This meta-analysis did find improvements in the health-related quality of life in patients undergoing PSO surgery for adult spinal deformity.

The Sagittal Tibial Tubercle-Trochlear Groove Distance as a Measurement of Sagittal Imbalance in Patients with Symptomatic Patellofemoral Chondral Lesions.

Objective. To measure the sagittal alignment of the tibial tubercle through the sagittal tibial tubercle-trochlear groove (sTTTG) distance in patients with and without patellar chondral lesions. Design. Patients treated with patellofemoral cartilage restoration or repair procedures were retrospectively reviewed (group 1; N = 17). A control group of patients (group 2; N = 20) undergoing partial meniscectomy with normal patellar cartilage was included. An asymptomatic patellar chondrosis group (group 3; N = 15) was identified as patients undergoing partial meniscectomy with patellar cartilage wear. The sTTTG was measured on the preoperative axial T2 magnetic resonance imaging (MRI) sequence. The first point was the nadir of the anterior trochlear cartilage, and the second point was the anterior tibial tubercle. A line was drawn between these points, perpendicular to the posterior condylar axis. Comparisons were made between the 3 groups using analysis of variance testing with Bonferroni corrections. Significance was defined as P < 0.05. Results. The mean sTTTG was significantly more posterior in group 1 (5.9 ± 5.5 mm posterior to the trochlear groove) relative to group 2 (0.8 ± 5.3 mm posterior; P = 0.018). The mean value for group 3 (2.7 ± 5.3 mm posterior) fell between group 1 and 3 but was not significantly different from group 1 (P = 0.31) or group 2 (P = 0.89). There were no significant differences with regards to sulcus angle, Caton-Deschamps Index, TTTG, or knee flexion angle on the MRI scan. Conclusions. A more posteriorly positioned tibial tubercle was observed in patients with patellar cartilage lesions relative to those with intact patellar cartilage. Intermediate positioning was observed in patients with asymptomatic patellar chondral wear. Level of Evidence. Level 3 diagnostic study.

Frontal and sagittal imbalance in patients with adolescent idiopathic deformity.

The human spinal column underwent many significant changes over the 4.5 million years of our ancestral bipedalism. The main change, however, came with acquiring multiple curvatures in the sagittal plane. This alteration seems to have exposed a weakness in our body's keystone and made us susceptible to thus far unbeknown problems of the spine because it has been noted that idiopathic scoliosis has not been observed in other primates. Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine causing an imbalance of the trunk as it increases in magnitude. A scoliotic curve comprises three components, the coronal, sagittal, and axial so that each curve can affect the global balance of the body differently. Patients with significant scoliotic deformities often find themselves at a biomechanical disadvantage when it comes to energy expenditure and keeping an upright stance. The pioneers of scoliosis research recognized the need for describing and quantifying deformity to better understand it, so they first translated clinical measurements to radiographs and built from there. The development of concepts like defining a curve by its end vertebrae and measuring its magnitude, assessing global spinal balance, describing the stable zone, and pinpointing the stable vertebra all followed suit. The importance of sagittal balance and restoring sagittal parameters during treatment was emphasized. In a quest to bring order to chaos, some tried to classify various scoliotic curve types. These classifications helped steer treatment decisions but were found lacking in many aspects. So far, a widely accepted three-dimensional classification of scoliosis still does not exist. This review aims to provide the reader with an overview of the development of balance and imbalance concepts in scoliosis.

The Vertical Tibial Tubercle-Trochlear Groove Distance as a Measurement of Sagittal Imbalance in Patients with Symptomatic Patellofemoral Chondral Lesions

There are currently no objective measurements to guide the use of tibial tubercle osteotomies for patellar cartilage defects without instability. This study evaluated the vertical tibial tubercle-trochlear groove distance (vTTTG) in patients with and without patellar chondral lesions.

Sarcopenia is related to spinal sagittal imbalance in patients with spinopelvic mismatch.

To clarify the relationship between sarcopenia and spinopelvic parameters. Among outpatients of spine surgery department, 126 patients (mean age 77.2years. M/F = 71/55) were included. We diagnosed patients with sarcopenia using the diagnostic algorithm of the Asian Working Group for Sarcopenia. Spinopelvic parameters and the prevalence of spinopelvic mismatch (pelvic incidence minus lumbar lordosis ≥ 10°) were investigated and compared between patients with and without sarcopenia. Furthermore, we compared the spinopelvic parameters between the Sarcopenia and No Sarcopenia groups under each condition of spinopelvic match and mismatch. The prevalence of sarcopenia in this study was 21.4%. Overall, the spinopelvic parameters except thoracic kyphosis (TK) (Sarcopenia: 34.7°, No Sarcopenia: 24.3°, p < 0.01) were not significantly different between the Sarcopenia and No Sarcopenia groups. Prevalence of patients with spinopelvic mismatch was also not significantly different between the Sarcopenia and No Sarcopenia groups (37.0% vs. 42.4%, p = 0.66). Among patients without spinopelvic mismatch, there was no spinopelvic parameter with a significant difference between the 2 groups. However, among patients with spinopelvic mismatch, sagittal vertebral axis (SVA) (115.7mm vs. 58.7mm, p < 0.01) and TK (36.6° vs. 21.3°, p < 0.01) of the Sarcopenia group were significantly larger than those of the No Sarcopenia group. Moreover, sarcopenia was independently related to a significant increase in SVA (β = 50.7, p < 0.01) and TK (β = 14.0, p < 0.01) in patients with spinopelvic mismatch, after adjustment for age. Sarcopenia is related to spinal sagittal imbalance because of insufficient compensation by flattening thoracic kyphosis in patients with spinopelvic mismatch. These slides can be retrieved under Electronic Supplementary Material.

Sagittal imbalance in patients with lumbar spinal stenosis and outcomes after simple decompression surgery

Background ContextLumbar spinal stenosis (LSS) is the most common lumbar degenerative disease, and sagittal imbalance is uncommon. Forward-bending posture, which is primarily caused by buckling of the ligamentum flavum, may be improved via simple decompression surgery. PurposeThe objectives of this study were to identify the risk factors for sagittal imbalance and to describe the outcomes of simple decompression surgery. Study DesignThis is a retrospective nested case-control study Patient SampleThis was a retrospective study that included 83 consecutive patients (M:F=46:37; mean age, 68.5±7.7 years) who underwent decompression surgery and a minimum of 12 months of follow-up. Outcome MeasuresThe primary end point was normalization of sagittal imbalance after decompression surgery. MethodsSagittal imbalance was defined as a C7 sagittal vertical axis (SVA) ≥40 mm on a 36-inch-long lateral whole spine radiograph. Logistic regression analysis was used to identify the risk factors for sagittal imbalance. Bilateral decompression was performed via a unilateral approach with a tubular retractor. The SVA was measured on serial radiographs performed 1, 3, 6, and 12 months postoperatively. The prognostic factors for sagittal balance recovery were determined based on various clinical and radiological parameters. ResultsSagittal imbalance was observed in 54% (45/83) of patients, and its risk factors were old age and a large mismatch between pelvic incidence and lumbar lordosis. The 1-year normalization rate was 73% after decompression surgery, and the median time to normalization was 1 to 3 months. Patients who did not experience SVA normalization exhibited low thoracic kyphosis (hazard ratio [HR], 1.04; 95% confidence interval [CI], 1.02–1.10) (p<.01) and spondylolisthesis (HR, 0.33; 95% CI, 0.17–0.61) before surgery. ConclusionsSagittal imbalance was observed in more than 50% of LSS patients, but this imbalance was correctable via simple decompression surgery in 70% of patients.

Coronal curvature and spinal imbalance in degenerative lumbar scoliosis: disc degeneration is associated.

A retrospective radiographical study. To determine the association between disc degeneration and spinal malalignment on both coronal and sagittal planes in patients with degenerative lumbar scoliosis (DLS). In recent years, a thorough understanding of spinal coronal balance and sagittal alignment has become more and more important in treating patients with DLS. Although degeneration of discs has been generally accepted as the main cause of DLS, to date no study has documented the relationships between disc degeneration and the curve magnitude as well as spinal imbalance. In this study, 57 patients with DLS were recruited. Degeneration of the apical disc, lower end vertebral (EV) discs and regional lumbar discs (L1-L2 and L5-S1) were quantitatively evaluated by the Pfirrmann score based on T2-weighted magnetic resonance images. Radiographical parameters including Cobb angle, coronal trunk shift, sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence, pelvic tilt, and sacral slope were measured from long-cassette standing upright radiographs. Subjects were assigned to 4 groups: both coronal and sagittal balanced (C+ S+); coronal imbalanced but sagittal balanced (C- S+); coronal balanced but sagittal imbalanced (C+ S-); and both coronal and sagittal imbalanced (C- S-). The Spearman correlation was used to identify the relationship between the Pfirrmann score of disc degeneration and radiographical parameters. Analysis of variance 2×2 factorial design was performed to identify the decisive factors affecting coronal and sagittal balance. On the basis of the criteria for each group, 19 patients were assigned to group A (C+ S+), 10 patients to group B (C- S+), 11 patients to group C (C+ S-), and 17 patients to group D (C- S-). The Pfirrmann score of regional lumbar disc degeneration strongly correlated with Cobb angle, SVA, TK, and LL (r = -0.364, -0.386, 0.283, and 0.479, respectively, P < 0.01). Specifically, the Pfirrmann score of apical disc degeneration correlated with Cobb angle, whereas degeneration of lower EV discs correlated with SVA, TK, and LL. On the basis of analysis of variance 2 × 2 factorial design, the score of the lower EV disc degeneration significantly correlated with sagittal balance (P < 0.05). This study demonstrated that the lower EV disc degeneration strongly correlated with sagittal imbalance in patients with DLS, implying that disc degeneration may be regarded as a potential risk factor for sagittal imbalance. This result strengthened the importance of not selecting the lower EV as the lower instrumented vertebra during the surgical decision making, which may lead to deterioration of sagittal balance. Disc degeneration was also strongly correlated with sagittal malalignment, as demonstrated by a more positive SVA, decreased TK and LL, providing insight into reasons for low quality of life in elderly patients with DLS.

Comparison of Sagittal Spinopelvic Alignment between Lumbar Degenerative Spondylolisthesis and Degenerative Spinal Stenosis.

ObjectiveThe purpose of this study was to evaluate the differences in sagittal spinopelvic alignment between lumbar degenerative spondylolisthesis (DSPL) and degenerative spinal stenosis (DSS).MethodsSeventy patients with DSPL and 72 patients with DSS who were treated with lumbar interbody fusion surgery were included in this study. The following spinopelvic parameters were measured on whole spine lateral radiographs in a standing position : pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis angle (LL), L4-S1 segmental lumbar angle (SLL), thoracic kyphosis (TK), and sagittal vertical axis from the C7 plumb line (SVA). Two groups were subdivided by SVA value, respectively. Normal SVA subgroup and positive SVA subgroup were divided as SVA value (<50 mm and ≥50 mm). Spinopelvic parameters/PI ratios were assessed and compared between the groups.ResultsThe PI of DSPL was significantly greater than that of DSS (p=0.000). The SVA of DSPL was significantly greater than that of DSS (p=0.001). In sub-group analysis between the positive (34.3%) and normal SVA (65.7%), there were significant differences in LL/PI and SLL/PI (p<0.05) in the DSPL group. In sub-group analysis between the positive (12.5%) and normal SVA (87.5%), there were significant differences in PT/PI, SS/PI, LL/PI and SLL/PI ratios (p<0.05) in the DSS group.ConclusionPatients with lumbar degenerative spondylolisthesis have the propensity for sagittal imbalance and higher pelvic incidence compared with those with degenerative spinal stenosis. Sagittal imbalance in patients with DSPL is significantly correlated with the loss of lumbar lordosis, especially loss of segmental lumbar lordosis.

Radiographical Predictors for Postoperative Sagittal Imbalance in Patients With Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis After Lumbar Pedicle Subtraction Osteotomy

A retrospective radiographical study. To identify the radiographical predictors for sagittal imbalance in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis (AS) after 1-level lumbar pedicle subtraction osteotomy (PSO). Few studies had correlated the preoperative sagittal parameters with postoperative sagittal alignments to determine the radiographical predictors for postoperative sagittal imbalance in patients with AS after 1-level lumbar PSO. Thirty-six patients with thoracolumbar kyphosis secondary to AS who underwent 1-level lumbar PSO were recruited with a minimal follow-up of 24 months (mean = 27.4 mo; range, 24-53 mo). Correlation analysis and subsequent stepwise multiple regression analysis were used to evaluate the correlations between preoperative parameters, including global kyphosis, local kyphosis, thoracic kyphosis, thoracolumbar Cobb angle, lumbar lordosis, pelvic incidence (PI), pelvic tilt, sacral slope, and sagittal vertical axis (SVA), as well as SVA at the last follow-up. All these patients were further divided into 2 groups according to the PI value (group A: PI >50°; group B: PI ≤50°). The correction outcomes were compared between these 2 groups. The preoperative SVA was not significantly different between group A and group B (157.6 mm vs. 124.5 mm; P> 0.05), and both groups had similar magnitudes of kyphosis corrections at the last follow-up (global kyphosis: 42.9° vs. 46.1°; local kyphosis: 42.7° vs. 40.5°; lumbar lordosis: 35.7° vs. 43.0°). However, group A patients had significantly larger SVA at the last follow-up (73.2 mm vs. 28.7 mm; P< 0.05) and a higher incidence of postoperative sagittal imbalance (77.8% vs. 25.9%; P< 0.05) than those in group B. The stepwise multiple regression analysis demonstrated that both preoperative SVA and PI were significant independent predictors of postoperative sagittal alignments, which explained 52.0% and 9.7% of the variability of SVA at the last follow-up, respectively. Patients with AS with either larger preoperative SVA or larger PI are more likely to experience failed sagittal realignments after 1-level lumbar PSO. For these patients, additional osteotomies may be recommended for satisfactory correction outcomes. 4.

Early Outcomes of Minimally Invasive Anterior Longitudinal Ligament Release for Correction of Sagittal Imbalance in Patients with Adult Spinal Deformity

The object of this study was to evaluate a novel surgical technique in the treatment of adult degenerative scoliosis and present our early experience with the minimally invasive lateral approach for anterior longitudinal ligament release to provide lumbar lordosis and examine its impact on sagittal balance. Methods. All patients with adult spinal deformity (ASD) treated with the minimally invasive lateral retroperitoneal transpsoas interbody fusion (MIS LIF) for release of the anterior longitudinal ligament were examined. Patient demographics, clinical data, spinopelvic parameters, and outcome measures were recorded. Results. Seven patients underwent release of the anterior longitudinal ligament (ALR) to improve sagittal imbalance. All cases were split into anterior and posterior stages, with mean estimated blood loss of 125 cc and 530 cc, respectively. Average hospital stay was 8.3 days, and mean follow-up time was 9.1 months. Comparing pre- and postoperative 36′′ standing X-rays, the authors discovered a mean increase in global lumbar lordosis of 24 degrees, increase in segmental lumbar lordosis of 17 degrees per level of ALL released, decrease in pelvic tilt of 7 degrees, and decrease in sagittal vertical axis of 4.9 cm. At the last followup, there was a mean improvement in VAS and ODI scores of 26.2% and 18.3%. Conclusions. In the authors' early experience, release of the anterior longitudinal ligament using the minimally invasive lateral retroperitoneal transpsoas approach may be a feasible alternative in correcting sagittal deformity.