[Spondylolisthesis]. / Spondylolisthese.

Spondylolisthesis is a frequent disease that is found in 20% of the adult population and is particularly accompanied by lumbar back pain. Degenerative spondylolisthesis develops in adulthood and is most often found in the L4/5 segment, in contrast to nondegenerative spondylolisthesis which is most often situated in the L5/S1 segment. Prior to every treatment the heterogeneous disease pattern has to be classified according to the severity grade of the olisthesis and to the Spinal Deformity Study Group (SDSG) classification. High-grade spondylolisthesis should preferably be surgically treated and low-grade spondylolisthesis should preferably be treated conservatively. In approximately 50% of all recently acquired spondylolistheses healing of the lysis can be achieved by a consequently carried out conservative treatment.

Utility of intraoperative neurophysiological monitoring in detecting motor and sensory nerve injuries in pediatric high-grade spondylolisthesis.

BACKGROUND CONTEXT: Intraoperative neuromonitoring (IONM) during surgical correction of spinal deformity has been shown to reduce iatrogenic injury in pediatric and adult populations. Although motor-evoked potentials (MEP), somatosensory-evoked potentials (SSEP), and electromyography (EMG) have been shown to be highly sensitive and specific in detecting spinal cord and nerve root injuries, their utility in detecting motor and sensory nerve root injury in pediatric high-grade spondylolisthesis (HGS) remains unknown. PURPOSE: We aim to assess the diagnostic accuracy and therapeutic impact of unimodal and multimodal IONM in the surgical management of HGS. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Pediatric patients undergoing posterior spinal fusion (PSF) for treatment of HGS. OUTCOME MEASURES: Data on patient demographics, spinopelvic and spondylolisthesis parameters, and the presence of pre-and postoperative neurological deficits were collected. METHODS: Intraoperative MEP, SSEP, and EMG alerts were recorded. Alert criteria were defined as a change in amplitude of more than 50% for MEP and/or SSEP, with or without change in latency, and more than 10 seconds of sustained EMG activity. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for each modality and the combination of MEP and SSEP. The 95% confidence intervals (CIs) were calculated using the exact (Clopper-Pearson) method. RESULTS: Fifty-four pediatric patients with HGS undergoing PSF between 2003 and 2021 in a single tertiary center were included. Seventy-two percent (39/54) of patients were female; the average age of patients was 13.7±2.3 years. The sensitivity of MEP in detecting new postoperative neurologic deficit was 92.3% (95% CI [64.0-99.8]), SSEP 77.8% (95% CI [40.0-97.2]), EMG 69.2% (95% CI [38.6-90.9]), and combination MEP and SSEP 100% (95% CI [73.5-100]). The specificity of MEP was 80.0% (95% CI [64.4-91.0]), SSEP 95.1% (95% CI [83.5-99.4]), EMG 65.9% (95% CI [49.4-79.9]), and combination MEP and SSEP 82.9% (95% CI [67.9-92.9]). The accuracy of SSEP was 92.0% (95% CI [80.8%-97.8%]), and the combination of MEP and SSEP was 86.8% (95% CI [74.7%-94.5%]). Twelve (22.2%) patients had a new motor or sensory deficit diagnosed immediately postoperatively. Nine patients made a full recovery, and 3 had some neurologic deficit on final follow-up. CONCLUSION: Unimodal IONM using SSEP and MEP alone were accurate in diagnosing sensory and motor nerve root injuries, respectively. The diagnostic accuracy in predicting motor and sensory nerve injuries in pediatric HGS improved further with the use of multimodal IONM (combining MEP and SEP). We recommend the utilization of multimodal IONM in all HGS PSF surgeries.

Response to Preoperative Steroid Injections Predicts Surgical Outcomes in Patients Undergoing Fusion for Isthmic Spondylolisthesis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The decision to pursue operative intervention for patients with isthmic spondylolisthesis is complex. Although steroid injections are a well-accepted therapeutic modality that may delay or obviate surgery, little is known regarding their ability to predict surgical outcomes. SUMMARY OF BACKGROUND DATA: Here, we examine whether improvement after preoperative steroid injections can accurately predict clinical outcomes after surgery. METHODS: A retrospective cohort analysis was performed on adult patients undergoing primary posterolateral lumbar fusion for isthmic spondylolisthesis between 2013 and 2021. Data were stratified into a control (no preoperative injection) group and an injection group (received a preoperative diagnostic and therapeutic injection). We collected demographic data, peri-injection visual analog pain scores (VAS) pain scores, PROMIS pain interference and physical function scores, Oswestry Disability Index, and VAS pain (back and leg). Student t test was utilized to compare baseline group characteristics. Linear regression was performed comparing changes in peri-injection VAS pain scores and postoperative measures. RESULTS: Seventy-three patients did not receive a preoperative injection and were included in the control group. Fifty-nine patients were included in the injection group. Of patients who received an injection, 73% had >50% relief of their preinjection VAS pain score. Linear regression revealed a positive interaction between the injection efficacy and postoperative pain relief as measured by VAS leg scores ( P <0.05). There was also an association between injection efficacy and back pain relief, though this did not achieve statistical significance ( P =0.068). No association was found between injection efficacy and improvement in Oswestry Disability Index or PROMIS measures. CONCLUSIONS: Steroid injections are often utilized in the nonoperative therapeutic management of patients with lumbar spine disease. Here, we demonstrate the diagnostic value of steroid injections in predicting postoperative leg pain relief in patients undergoing posterolateral fusion for isthmic spondylolisthesis.

Usefulness of discography, discoblock and a new mechanical method for identifying a painful segment/disc.

BACKGROUND: We previously described a procedure for eliciting deep spatial discrimination of individual segments in the healthy lumbar spine of normal subjects: the percutaneous mechanical provocation (PMP) test. Our goal was to devise a method for accurate identification of the spinal level of pathology in chronic low back pain (CLBP). In the present study, we validated the PMP test, using a subgroup of CLBP patients with isthmic spondylolisthesis (IS). Because there is clinical consensus that IS back pain originates in the slipped segment/disc, the level of pathology can be directly compared to the result of the PMP test. The test is agnostic with respect to the underlying pathological mechanism, and therefore might be useful in identifying the involved segment(s) irrespective of the painful structure. METHODS: In 37 patients with confirmed IS (slippage 3-15mm), we compared sensitivity between the PMP test, the widely used provocative discography test and the discoblock test. RESULTS: The PMP test reliably identified the slip level in patients with IS, with sensitivity of 92%. Accepting the slipped disc as the origin of pain in IS, the sensitivity of the provocative discography and discoblock tests were 49% and 35%, respectively: i.e., too low to be contributive in clinical practice. CONCLUSIONS: The PMP test reliably identified the origin of localized pain in IS as the slip level, but should be used with care in CLBP patients in selecting discogenic pain patients for fusion surgery, since the specificity of the test is not known and it may be positive for any origin of localized pain.

[Lumbar spinal stenosis]. / Lumbale Spinalkanalstenose.

Lumbar spinal stenosis (LSS) represents a frequent degenerative condition, however, striking a clear correlation between typical symptoms and imaging features remains a challenge. Reasons are a high prevalence of radiological LSS in the older population, a considerable percentage of asymptomatic LSS and the existence of differential diagnoses with similar symptomatology. This discrepancy also affects the outcomes - especially of surgically treated patients with LSS. When considering surgical decompression of LSS, the decision with regards to additive instrumentation and/or fusion remains a controversial point of discussion, in particular at the presence of degenerative spondylolisthesis. Recent, well-designed studies, however, clearly point towards a non-inferiority of decompression alone as opposed to the more invasive strategies.

Radiographic analysis of dynamic lumbar motion during the five-repetition sit-to-stand test in degenerative lumbar spondylolisthesis.

BACKGROUND: To investigate the mechanisms of low back pain triggered by the five-repetition sit-to-stand test (5R-STS test) in degenerative lumbar spondylolisthesis (DLS) from radiographic perspective, as well as to determine the most useful diagnostic modalities in the evaluation of segmental instability. METHODS: We retrospectively performed a study of 78 patients (23 men and 55 women) with symptomatic DLS at L4/5 in our institution between April 2020 and December 2021. Each patient was assessed by using the 5R-STS test and received a series of radiographs including the upright standing, normal sitting, standing flexion-extension radiographs, and supine sagittal MR images. Enrolled patients were divided into two groups based on the 5R-STS test score: severe group and mild group. Translational and angular motion was determined by comparing normal sitting radiograph (N) with upright standing radiograph (U) (Combined, NU), flexion/extension radiographs (FE) as well as normal sitting radiograph (N) with a supine sagittal MR image (sMR) (Combined, N-sMR). RESULTS: Overall, 78 patients were enrolled, and there were 31(39.7%) patients in group S and 47(60.3%) patients in group M, with an average age of 60.7 ± 8.4 years. The normal sitting radiograph demonstrated the maximum slip percentage (SP) and the highest kyphotic angle both in group S and group M. Compared with group M, group S revealed significantly higher SP in the normal sitting position (24.1 vs 19.6; p = 0.002). The lumbar slip angular in group S with a sitting position was significantly higher than that in group M (-5.2 vs -1.3; p < 0.001). All patients in group S had objective functional impairment (OFI) and 28 patients of them were diagnosed with lumbar instability by using the combination of normal sitting radiograph (N) and supine sagittal MR image (sMR) (Combined, N-sMR). CONCLUSION: DLS patients with positive sign of the 5R-STS test is a distinct subgroup associated with lumbar instability. The modality of the combination of normal sitting radiograph (N) and supine sagittal MR image (sMR) had a significant advantage in terms of the ability to identify segmental instability.

Current Clinical Concepts: Management of Common Lumbar Spine Posterior Column Disorders in Young, Active Individuals.

Although posterior column disorders, such as spondylolysis and spondylolisthesis, are not commonly encountered in the general population, athletic trainers frequently see these conditions in athletic and active individuals due to the repetitive spinal extension and rotational loads placed on the pars interarticularis while participating in sport. Athletic trainers can successfully evaluate patients with posterior column disorders by performing a complete and comprehensive clinical examination to identify the location of pain, test spinal stability, and recognize compensatory movement patterns. Conservative management typically leads to a successful outcome in this population, with rest, bracing, and the use of therapeutic exercise having the best supporting evidence. In this Current Clinical Concepts review, we outlined the etiology and risk factors frequently associated with disorders of the posterior column. Additionally, we synthesized the literature for common evaluation techniques and interventions associated with the posterior column and provided a proposed rehabilitation progression to use in a younger, athletic population.

Evaluation and Management of Cauda Equina Syndrome.

Cauda equina syndrome is a potentially devastating spinal condition. The diagnosis of cauda equina syndrome lacks sensitivity and specificity, sometimes occurring after irreparable neurological damage has happened. Timely diagnosis and treatment is imperative for optimal outcomes and for avoiding medicolegal ramifications. Cauda equina syndrome results from conditions that compress the nerves in the lumbosacral spinal canal. Although no consensus definition exists, it generally presents with varying degrees of sensory loss, motor weakness, and bowel and bladder dysfunction (the latter of which is required to definitively establish the diagnosis). A thorough history and physical exam is imperative, followed by magnetic resonance or computed tomography imaging myelogram to aid in diagnosis and treatment. Once suspected, emergent spinal surgery referral is indicated, along with urgent decompression. Even with expeditious surgery, improvements remain inconsistent. However, early intervention has been shown to portend greater chance of neurologic recovery. All providers in clinical practice must understand the severity of this condition. Providers can optimize long-term patient outcomes and minimize the risk of litigation by open communication, good clinical practice, thorough documentation, and expeditious care.

Decompression alone versus decompression and instrumented fusion for the treatment of isthmic spondylolisthesis: a randomized controlled trial.

OBJECTIVE: The most advocated surgical technique to treat symptoms of isthmic spondylolisthesis is decompression with instrumented fusion. A less-invasive classical approach has also been reported, which consists of decompression only. In this study the authors compared the clinical outcomes of decompression only with those of decompression with instrumented fusion in patients with isthmic spondylolisthesis. METHODS: Eighty-four patients with lumbar radiculopathy or neurogenic claudication secondary to low-grade isthmic spondylolisthesis were randomly assigned to decompression only (n = 43) or decompression with instrumented fusion (n = 41). Primary outcome parameters were scores on the Roland Disability Questionnaire (RDQ), separate visual analog scales (VASs) for back pain and leg pain, and patient report of perceived recovery at 12-week and 2-year follow-ups. The proportion of reoperations was scored as a secondary outcome measure. Repeated measures ANOVA according to the intention-to-treat principle was performed. RESULTS: Decompression alone did not show superiority in terms of disability scores at 12-week follow-up (p = 0.32, 95% CI -4.02 to 1.34), nor in any other outcome measure. At 2-year follow-up, RDQ disability scores improved more in the fusion group (10.3, 95% CI 3.9-8.2, vs 6.0, 95% CI 8.2-12.4; p = 0.006, 95% CI -7.3 to -1.3). Likewise, back pain decreased more in the fusion group (difference: -18.3 mm, CI -32.1 to -4.4, p = 0.01) on a 100-mm VAS scale, and a higher proportion of patients perceived recovery as showing "good results" (44% vs 74%, p = 0.01). Cumulative probabilities for reoperation were 47% in the decompression and 13% in the fusion group (p < 0.001) at the 2-year follow-up. CONCLUSIONS: In patients with isthmic spondylolisthesis, decompression with instrumented fusion resulted in comparable short-term results, significantly better long-term outcomes, and fewer reoperations than decompression alone. Decompression with instrumented fusion is a superior surgical technique that should in general be offered as a first treatment option for isthmic spondylolisthesis, but not for degenerative spondylolisthesis, which has a different etiology.

Comparison of outcomes between indirect decompression of oblique lumbar interbody fusion and MIS-TLIF in one single-level lumbar spondylosis.

Minimal invasive spinal fusion has become popular in the last decade. Oblique lumbar interbody fusion (OLIF) is a relatively new surgical technique and could avoid back muscle stripping and posterior complex destruction as in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Between December 2016 and September 2018, patients with single level degenerative spondylosis were selected to enroll in this retrospective study. A total of 21 patients that underwent OLIF and 41 patients that received MIS-TLIF were enrolled. OLIF showed significantly less blood loss and shorter surgery time compared to MIS-TLIF (p < 0.05). The improvement in segmental lordosis and coronal balance was significantly more in OLIF group than MIS-TLIF group (p < 0.05). When comparing with MIS-TLIF, OLIF was significantly better in Oswestry Disability Index (ODI) and visual analogue scale for back pain improvement at post-operative 6 months (p < 0.05). Both OLIF and MIS-TLIF are becoming mainstream procedures for lumbar degenerative-related disease, especially for spondylolisthesis. However, the indirect decompression of OLIF has shown to have less perioperative blood loss and shorter surgery time than that of MIS-TLIF. In addition, OLIF gives superior outcome in restoring segmental lordosis and coronal imbalance. While both OLIF and MIS-TLIF provide optimal clinical outcomes, upon comparison between the two techniques, the indirect decompression of OLIF seems to be a superior option in modern days.

One-year clinical outcome after full-endoscopic interlaminar lumbar discectomy for isthmic lumbar spondylolisthesis: Two case reports.

RATIONALE: For isthmic lumbar spondylolisthesis (ILS) associated with the removal of herniation, it remains challenging to perform less invasive and minimally disruptive procedures. Good results could potentially be obtained by further preserving the posterior elements in full-endoscopic lumbar discectomy (FESS), which is less invasive than microenscopic surgery (MES). PATIENT CONCERNS: One patient complained of left leg pain, and another patient complained of right leg pain and low back pain. DIAGNOSES: Two patients with ILS and Meyerding Grade 1 lumbar spondylolisthesis. INTERVENTIONS: We performed a full-endoscopic lumbar discectomy via the interlaminar space (FESS-IL) for L5/S1 lumbar disc herniation (LDH) accompanied by isthmic lumbar spondylolisthesis. FESS-IL was performed in 2 patients with radiculopathy caused by different types of LDH using a full endoscopic system with a 4.1 mm working channel and 6.9 mm outer diameter. A 3.5-mm diameter high-speed drill was used in one patient for an upward-migrated LDH in the inner-rim of the infravertebral border. The other patient underwent minimal resection without bone resection. OUTCOMES: The one-year clinical outcome included confirmation of pain relief and evacuation of migrated LDH on magnetic resonance imaging in all patients. There was no progression of slippage on radiography. The mean operative time was 82 min, and no complication was observed. The one-year clinical outcome demonstrated sufficient pain relief. LESSONS THE Y: ear postoperative outcome showed improvement. We believe that FESS-IL is a viable alternative operative approach for LDH for ILS.

Lumbosacral Spondylolysis and Spondylolisthesis.

Repetitive stress on the lumbosacral spine during sporting activity places the athletic patient at risk of developing symptomatic pars defect. Clinical history, physical examination, and diagnostic imaging are important to distinguish spondylolysis from other causes of lower back pain. Early pars stress reaction can be identified with advanced imaging, before the development of cortical fracture or vertebral slip progression to spondylolisthesis. Conservative management is first-line for low-grade injury with surgical intervention indicated for refractory symptoms, severe spondylolisthesis, or considerable neurologic deficit. Prompt diagnosis and management of spondylolysis leads to good outcomes and return to competition for most athletes.

In-hospital Course and Complications of Laminectomy Alone Versus Laminectomy Plus Instrumented Posterolateral Fusion for Lumbar Degenerative Spondylolisthesis: A Retrospective Analysis of 1804 Patients from the NSQIP Database.

STUDY DESIGN: Retrospective analysis of data from the National Surgical Quality Improvement Program (NSQIP). OBJECTIVE: We sought to compare the short-term outcomes of laminectomy with/without fusion for single-level lumbar degenerative spondylolisthesis (DS). SUMMARY OF BACKGROUND DATA: Lumbar DS is a common cause of low back and radicular pain. Controversy remains over the safety and efficacy of fusion in addition to standard decompressive surgery. METHODS: Patients with lumbar DS who underwent laminectomy alone or laminectomy plus posterolateral fusion at a single level were identified from the 2012-2017 NSQIP database. Outcomes included 30-day mortality, major complication, reoperation, readmission, as well as operative duration, need for blood transfusion, length of stay (LOS), and discharge destination. Outcomes were compared between treatment groups by multivariable regression, adjusting for age, sex, and comorbidities (modified Frailty Index). Effect sizes were reported by adjusted odds ratio (aOR) or mean difference (aMD). RESULTS: The study cohort consisted of 1804 patients; of these, 802 underwent laminectomy alone and 1002 laminectomy plus fusion. On both unadjusted and adjusted analyses, there was no difference in 30-day mortality, major complications, reoperation, or readmission. However, laminectomy plus fusion was associated with longer operative time (170.0 vs. 152.7 minutes; aMD 16.00 minutes, P < 0.001), longer hospital LOS (3.2 vs. 2.5 days; aMD 0.68, P < 0.001), more frequent need for intra- or postoperative blood transfusion (6.8% vs. 3.1%; aOR 2.24, P = 0.001), and less frequent discharge home (80.7% vs. 89.2%; aOR 0.46, P < 0.001). CONCLUSION: We found single-level laminectomy plus fusion for lumbar DS to have a comparable short-term safety profile to laminectomy alone. However, fusion was associated with longer operative time and LOS, higher risk of blood transfusion, and greater need for inpatient rehabilitation. These factors should be recognized by clinicians and discussed with patients in the context of their values when weighing surgical treatment of lumbar DS.Level of Evidence: 3.

Comparative Effectiveness of Microdecompression Alone vs Decompression Plus Instrumented Fusion in Lumbar Degenerative Spondylolisthesis.

Importance: Conflicting evidence and large practice variation are present in the surgical treatment of degenerative spondylolisthesis. More than 90% of surgical procedures in the United States include instrumented fusion compared with 50% or less in other countries. Objective: To evaluate whether the effectiveness of microdecompression alone is noninferior to decompression with instrumented fusion in a real-world setting. Design, Setting, and Participants: This multicenter comparative effectiveness study with a noninferiority design assessed prospective data from the Norwegian Registry for Spine Surgery. From September 19, 2007, to December 21, 2015, 1376 patients at 35 Norwegian orthopedic and neurosurgical departments underwent surgery for lumbar spinal stenosis with degenerative spondylolisthesis without scoliosis. After excluding patients undergoing laminectomy alone, fusion without instrumentation, or surgery in more than 2 levels and those with a former operation at the index level, 794 patients were included in the analyses, regardless of missing or incomplete follow-up data, before propensity score matching. Data were analyzed from March 20 to October 30, 2018. Exposures: Microdecompression alone or decompression with instrumented fusion. Main Outcomes and Measures: A reduction from baseline of 30% or greater in the Oswestry Disability Index at 12-month follow-up. Results: After propensity score matching, 570 patients (413 female [72%]; mean [SD] age, 64.7 [9.5] years) were included for comparison, with 285 undergoing microdecompression (mean [SD] age, 64.6 [9.8] years; 205 female [72%]) and 285 undergoing decompression with instrumented fusion (mean [SD] age, 64.8 [9.2] years; 208 female [73%]). The proportion of each type of procedure varied between departments. However, changes in outcome scores varied within patients but not between departments. The proportion of patients with improvement in the Oswestry Disability Index of at least 30% was 150 of 219 (68%) in the microdecompression group and 155 of 215 (72%) in the instrumentation group. The 95% CI (-12% to 5%) for the difference of -4% was above the predefined margin of noninferiority (-15%). Microdecompression alone was associated with shorter operation time (mean [SD], 89 [44] vs 180 [65] minutes; P < .001) and shorter hospital stay (mean [SD], 2.5 [2.4] vs 6.4 [3.0] days; P < .001). Conclusions and Relevance: Among patients with degenerative spondylolisthesis, the clinical effectiveness of microdecompression alone was noninferior to that of decompression with instrumented fusion. Microdecompression alone was also associated with shorter durations of surgery and hospital stay, supporting the suggestion that the less invasive procedure should be considered for most patients.

Initial classification of low back and leg pain based on objective functional testing: a pilot study of machine learning applied to diagnostics.

OBJECTIVE: The five-repetition sit-to-stand (5R-STS) test was designed to capture objective functional impairment and thus provided an adjunctive dimension in patient assessment. The clinical interpretability and confounders of the 5R-STS remain poorly understood. In clinical use, it became apparent that 5R-STS performance may differ between patients with lumbar disk herniation (LDH), lumbar spinal stenosis (LSS) with or without low-grade spondylolisthesis, and chronic low back pain (CLBP). We seek to evaluate the extent of diagnostic information contained within 5R-STS testing. METHODS: Patients were classified into gold standard diagnostic categories based on history, physical examination, and imaging. Crude and adjusted comparisons of 5R-STS performance were carried out among the three diagnostic categories. Subsequently, a machine learning algorithm was trained to classify patients into the three categories using only 5R-STS test time and patient age, gender, height, and weight. RESULTS: From two prospective studies, 262 patients were included. Significant differences in crude and adjusted test times were observed among the three diagnostic categories. At internal validation, classification accuracy was 96.2% (95% CI 87.099.5%). Classification sensitivity was 95.7%, 100%, and 100% for LDH, LSS, and CLBP, respectively. Similarly, classification specificity was 100%, 95.7%, and 100% for the three diagnostic categories. CONCLUSION: 5R-STS performance differs according to the etiology of back and leg pain, even after adjustment for demographic covariates. In combination with machine learning algorithms, OFI can be used to infer the etiology of spinal back and leg pain with accuracy comparable to other diagnostic tests used in clinical examination. These slides can be retrieved under Electronic Supplementary Material.

Back Injuries.

When searching for evidence-based answers about treating athletes with low back injury/pain, there are some difficulties. The first is defining who is an athlete. The second problem is that the lifetime prevalence of low back pain in the general population in our country approaches 100. Last, most studies published only deal with a narrow population of athletes, often performing very different types of physical activity. We searched the literature for studies that specifically evaluated athletes longitudinally. This article reviews the demographics, diagnostic challenges, history and physical examination, imaging choices, treatment, and controversies encountered when treating this population.

Global sagittal spinal alignment in patients with degenerative low-grade lumbar spondylolisthesis.

PURPOSE: Global sagittal spinal alignment undergoes changes on the basis of sagittal malalignment (trunk inclined forward) in natural degenerative progression. We hypothesized that this change would associate with the disease state of the degenerative lumbar spondylolisthesis (DS). This study aimed to evaluate the global sagittal spinal alignment of low-grade DS by classifying in accordance with sagittal vertical axis (SVA). METHODS: The DS group was classified into three types according to the adult spinal deformity classification: type 1, SVA < 40 mm; type 2, 40 mm ≤ SVA < 95 mm; and type 3, 95 mm ≤ SVA. Age and sagittal spinal parameters (thoracic kyphosis, lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI)) were compared among three types. RESULTS: There were statistically significant differences in age, LL, PI, and PT among the three types. In comparison between two types, there was a statistically significant difference between type 1 and type 2 and between type 1 and type 3, but not between type 2 and type 3 in these parameters. PI tended to increase as the type increases. Furthermore, there was significant difference between types 1 and 3. CONCLUSION: We evaluated the features of the DS types classified by sagittal alignment. Large PI is one of the risk factors for SVA deterioration of DS. PI may be involved in the onset and progression of DS.