Association Between Spinopelvic Parameters and Intravertebral Cleft in Osteoporosis Vertebral Compression Fractures

BACKGROUND

The high incidence of nonunion in osteoporosis vertebral compression fractures (OVCFs) among the elderly population is a significant concern. But the hypothesis about etiopathogenesis of the intravertebral cleft (IVC) is not convincing. This study aims to investigate the association between spinopelvic parameters and IVC.

METHODS

Patients with single segment IVC or healed vertebral compression fracture (HVCF) were retrospectively recruited for the study. Patients with IVC were assigned to the IVC group, the others were assigned to the HVCF group. We estimated whether IVC or HVCF locates the vertebra inflection point on lumbar lateral radiography. Distance between the sagittal line passing through the anterosuperior corner of S1and the center of the vertebra of healed fracture or with IVC (DSVA) and sacral slope (SS) were measured on lumbar lateral plain films. Intergroup spinopelvic parameters were analyzed. analysis to identify independent variables associated with IVC incidence. The receiver operating characteristics (ROC) curve was generated to identify the optimal cut-off point for statistically significant variables.

RESULTS

Sixty-five patients were included in the study. Thirty patients (mean age: 74 ± 7.16 years) had single-level IVC, and 35 patients (mean age: 67.71 ± 7.30 years) had single-level HVCF. Age, body mass index (BMI), and DSVA were statistically different between the groups (all P < 0.05). The occurrence of IVC was related to the DSVA in the multivariate logistic regression analysis (OR = 0.73, P < 0.05).

CONCLUSIONS

According to the results of this study, large DSVA was a risk factor for IVC formation in patients with OVCFs. Patients with global spinal malalignment should be actively observed during conservative treatment.

A Retrospective Study of the Effect of Spinopelvic Parameters on Fatty Infiltration in Paraspinal Muscles in Patients With Lumbar Spondylolisthesis

OBJECTIVE

The effect on fat infiltration (FI) of paraspinal muscles in degenerative lumbar spinal diseases has been demonstrated except for spinopelvic parameters. The present study is to identify the effect of spinopelvic parameters on FI of paraspinal muscle (PSM) and psoas major muscle (PMM) in patients with degenerative lumbar spondylolisthesis.

METHODS

A single-center, retrospective cross-sectional study of 160 patients with degenerative lumbar spondylolisthesis (DLS) and lumbar stenosis (LSS) who had lateral full-spine x-ray and lumbar spine magnetic resonance imaging was conducted. PSM and PMM FIs were defined as the ratio of fat to its muscle cross-sectional area. The FIs were compared among patients with different pelvic tilt (PT) and pelvic incidence (PI), respectively.

RESULTS

The PSM FI correlated significantly with pelvic parameters in DLS patients, but not in LSS patients. The PSM FI in pelvic retroversion (PT > 25°) was 0.54 ± 0.13, which was significantly higher in DLS patients than in normal pelvis (0.41 ± 0.14) and pelvic anteversion (PT < 5°) (0.34 ± 0.12). The PSM FI of DLS patients with large PI ( > 60°) was 0.50 ± 0.13, which was higher than those with small ( < 45°) and normal PI (0.37 ± 0.11 and 0.36 ± 0.13). However, the PSM FI of LSS patients didn't change significantly with PT or PI. Moreover, the PMM FI was about 0.10-0.15, which was significantly lower than the PSM FI, and changed with PT and PI in a similar way of PSM FI with much less in magnitude.

CONCLUSION

FI of the PSMs increased with greater pelvic retroversion or larger pelvic incidence in DLS patients, but not in LSS patients.

EOS® is reliable to evaluate spinopelvic parameters: a validation study

BACKGROUND

Sagittal and coronal standing radiographs have been the standard imaging for assessing spinal alignment. However, their disadvantages include distortion at the image edges and low interobserver reliability in some parameters. EOS® is a low-dose biplanar digital radiographic imaging system that can avoid distortion by obtaining high-definition images.

METHODS

This study aimed to evaluate spinopelvic parameters in conventional lateral C1S1 upright radiographs and EOS® images and compare them. Patients with non-deformity changes were subjected to routine clinical examinations. Plain AP and lateral X-ray radiographs were obtained along the entire spine length. Patients were also referred for full-length EOS® of the spine. Thoracic Kyphosis (TK), Lumbar Lordosis (LL), Pelvic Tilt (PT), Sacral Slope (SS), Pelvic Incidence (PI), and Sagittal Vertical Axis (SVA) were measured in the two studies by an orthopedic surgeon and a radiologist using PACS software. Also, the orthopedic surgeon evaluated the studies again after two weeks. Intra- and inter-observer reliability was then assessed using the interclass correlation coefficient (ICC). Also, the coefficient of variation was used to assess intra- and inter-observer reliability. Bland-Altman plots were drawn for each parameter.

RESULTS

The mean age was 48.2 ± 6.6 years. Among the 50 patients, 30 (60%) were female. The mean ICC for TK, LL, PT, SS, PI, and SVA in EOS® images are 0.95, 0.95, 0.92, 0.90, 0.94, and 0.98, respectively, and in C1S1 radiography images, it was 0.92, 0.87, 0.94, 0.88, 0.93, and 0.98, respectively which shows good to excellent results. The coefficient of variation for intraobserver reliability was relatively low (< 18.6%), while it showed higher percentages in evaluating interobserver reliability (< 54.5%). Also, the Bland-Altman plot showed good agreement for each parameter.

CONCLUSION

Spinopelvic parameters, e.g., TK, LL, SS, PI, and SS, in EOS® are reliable and comparable to those in conventional lateral upright C1S1 radiographs.

Three-column osteotomy in long constructs has lower rates of proximal junctional kyphosis and better restoration of lumbar lordosis than anterior column realignment

PURPOSE

Three-column osteotomies (TCOs) and minimally invasive techniques such as anterior column realignment (ACR) are powerful tools used to restore lumbar lordosis and sagittal alignment. We aimed to appraise the differences in construct and global spinal stability between TCOs and ACRs in long constructs.

METHODS

We identified consecutive patients who underwent a long construct lumbar or thoracolumbar fusion between January 2016 and November 2021. "Long construct" was any construct where the uppermost instrumented vertebra (UIV) was L2 or higher and the lowermost instrumented vertebra (LIV) was in the sacrum or ileum.

RESULTS

We identified 69 patients; 14 (20.3%) developed PJK throughout follow-up (mean 838 days). Female patients were less likely to suffer PJK (p = 0.009). TCO was more associated with open (versus minimally invasive) screw/rod placement, greater number of levels, higher UIV, greater rate of instrumentation to the ilium, and posterior (versus anterior) L5-S1 interbody placement versus the ACR cohort (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.005, respectively). Patients who developed PJK were more likely to have undergone ACR (12 (32.4%) versus 2 (6.3%, p = 0.007)). The TCO cohort had better improvement of lumbar lordosis despite similar preoperative measurements (ACR: 16.8 ± 3.78°, TCO: 23.0 ± 5.02°, p = 0.046). Pelvic incidence-lumbar lordosis mismatch had greater improvement after TCO (ACR: 14.8 ± 4.02°, TCO: 21.5 ± 5.10°, p = 0.042). By multivariate analysis, ACR increased odds of PJK by 6.1-times (95% confidence interval: 1.20-31.2, p = 0.29).

CONCLUSION

In patients with long constructs who undergo ACR or TCO, we experienced a 20% rate of PJK. TCO decreased PJK 6.1-times compared to ACR. TCO demonstrated greater improvement of some spinopelvic parameters.

Pelvic Incidence as a Predictor of Proximal Junctional Failure in Patients Undergoing Anterior Column Realignment with Anterior Longitudinal Ligament Release to Restore Lordosis in Adult Spinal Deformity: A Retrospective Cohort Study

OBJECTIVE

To identify variables that may contribute to the development of proximal junctional failure (PJF) in patients with long lumbo-sacral and thoraco-lumbo-pelvic constructs undergoing anterior column realignment (ACR) with anterior longitudinal ligament release (ALLR).

METHODS

Data of patients with adult spinal deformity who underwent ACR with ALLR at L3-4 were collected retrospectively from medical records and a prospectively maintained spine research database between 2016 and 2022.

RESULTS

Eleven (41%) developed PJF at a mean of 24 ± 21 months from the index surgery. The cohort was then divided into 2 groups for analysis, 13 subjects in the high pelvic incidence (PI) group (defined as PI ≥ 55°) and 14 subjects in the low PI group (defined as PI < 55°). Visual Analog Scale for back pain and Oswestry Disability Index decreased from 9.5 to 2.1 and 61 to 10 in the high PI group, and from 8.9 to 2.4 and 60.9 to 10.3 in the low PI group, respectively. PI (P = 0.004), sacral slope (P = 0.005), and postoperative PI-lumbar lordosis mismatch (P = 0.02) were found to be significant predictors of PJF. The receiver operator curve revealed a cutoff PI value ≤ 53° (95% confidence interval: 52°-64°), below which the risk of PJF becomes significantly higher in patients undergoing ACR with ALLR at L3-4.

CONCLUSIONS

PI may be a predictor of PJF and highly correlates with ACR-ALLR levels. In patients undergoing L3-4 ACR-ALLR, a PI value of ≤53° is associated with a significantly elevated risk of PJF. Preoperative planning of ACR-ALLR level based on normal sagittal alignment in otherwise healthy individuals may mitigate the risk of PJF development in patients with adult spinal deformity treated with ACR-ALLR.

Analysis of Rod Fracture at the Lumbosacral Junction Following Surgery for Adult Spinal Deformity

STUDY DESIGN

Retrospective study.

PURPOSE

This study aimed to investigate the differences in the characteristics of patients with rod fracture (RF) at the lumbosacral junction from those without RF following adult spinal deformity (ASD) surgery.

OVERVIEW OF LITERATURE

RF is a major complication following ASD surgery and may require reoperation because of pain and correction loss. The lumbosacral junction is a common RF site. However, risk factors for RFs at the lumbosacral junction remain unknown.

METHODS

The study included data from 100 patients who underwent ASD surgery between 2012 and 2020. Fifteen of these patients presented with RFs. Patient demographics, clinical outcomes, and radiographic parameters were evaluated in each group.

RESULTS

RFs were significantly more frequent in patients with a medical history of total hip arthroplasty (THA; p=0.01) or severe obesity (p=0.04). However, no significant differences in clinical outcomes, preoperative or postoperative measurements, or changes were found between pre- and postoperative radiographic parameters within the groups. Both pre- (p=0.01) and postoperative (p=0.02) anterior disc heights were significantly greater in the RF group than in the non-RF group. In the RF group, the postoperative lordotic angles of the lumbosacral junction significantly decreased compared with preoperative angles (p=0.02). Multiple logistic regression analysis demonstrated that a THA history (odds ratio, 34.2), severe obesity (odds ratio, 14.0), and preoperative anterior disc height (odds ratio, 1.2) were significant risk factors for RFs.

CONCLUSIONS

In this study, the greatest risk factors for postoperative lumbosacral RF after ASD surgery were THA history, severe obesity, and postoperative anterior disc height of ≥10. For patients at higher risk, the use of multirods is considered necessary.

A systematic review and update on diagnosis and treatment of new onset sacroiliac joint dysfunction after lumbar fusion

BACKGROUND

Sacroiliac joint dysfunction (SIJD) after lumbar/lumbosacral fusion has become increasingly recognized as the utilization of lumbar fusion has grown. Despite the significant morbidity associated with this condition, uncertainty regarding its diagnosis and treatment remains. We aim to update the current knowledge of the etiology, diagnosis, and treatment of post-lumbar surgery SIJD.

METHODS

PRISMA guidelines were used to search the PubMed/Medline, Web of Science, Cochrane Reviews, Embase, and OVID databases for literature published in the last 10 years. The ROBIS tool was utilized for risk of bias assessment. Statistical analyses were performed using the R foundation. A Fisher's exact test was performed to determine the risk of SIJD based on operative technique, gender, and symptom onset timeline. Odds ratios were reported with 95% confidence intervals. A p-value [Formula: see text] 0.05 was considered statistically significant.

RESULTS

Seventeen publications were included. The incidence of new onset SIJD was 7.0%. The mean age was 56 years, and the follow-up length was 30 months. SIJD was more common with fixed lumbar fusion vs floating fusion (OR = 1.48 [0.92, 2.37], p = 0.083), fusion of [Formula: see text] 3 segments (p < 0.05), and male gender increased incidence of SIJD (OR = 1.93 [1.27, 2.98], p = 0.001). Intra-articular injection decreased the Visual Analogue Scale (VAS) score by 75%, while radiofrequency ablation (RFA) reduced the score by 90%. An open approach resulted in a 13% reduction in VAS score versus 68 and 29% for SIJ fixation using the iFuse and DIANA approaches, respectively.

CONCLUSIONS

Lumbar fusion predisposes patients to SIJD, likely through manipulation of the SIJ's biomechanics. Definitive diagnosis of SIJD remains multifaceted and a newer modality such as SPECT/CT may find a future role. When conservative measures are ineffective, RFA and SIJ fixation using the iFuse System yield the greatest improvement VAS and ODI.

Deep learning algorithm for fully automated measurement of sagittal balance in adult spinal deformity

AIM

Deep learning (DL) algorithms can be used for automated analysis of medical imaging. The aim of this study was to assess the accuracy of an innovative, fully automated DL algorithm for analysis of sagittal balance in adult spinal deformity (ASD).

MATERIAL AND METHODS

Sagittal balance (sacral slope, pelvic tilt, pelvic incidence, lumbar lordosis and sagittal vertical axis) was evaluated in 141 preoperative and postoperative radiographs of patients with ASD. The DL, landmark-based measurements, were compared with the ground truth values from validated manual measurements.

RESULTS

The DL algorithm showed an excellent consistency with the ground truth measurements. The intra-class correlation coefficient between the DL and ground truth measurements was 0.71-0.99 for preoperative and 0.72-0.96 for postoperative measurements. The DL detection rate was 91.5% and 84% for preoperative and postoperative images, respectively.

CONCLUSION

This is the first study evaluating a complete automated DL algorithm for analysis of sagittal balance with high accuracy for all evaluated parameters. The excellent accuracy in the challenging pathology of ASD with long construct instrumentation demonstrates the eligibility and possibility for implementation in clinical routine.

Association of radiological severity of hip involvement with clinical characteristics and sagittal spinopelvic balance in patients with ankylosing spondylitis

INTRODUCTION

This is the first study to analyze the associations between the radiological severity of hip involvement with clinical characteristics and sagittal spinopelvic balance in patients with ankylosing spondylitis (AS).

METHOD

We evaluated 182 patients with AS who were referred to outpatient clinics. Patient demographic data and clinical and radiographic parameters were collected. Patients were divided into three groups based on the Bath Ankylosing Spondylitis Radiology Hip Index. Clinical characteristics and spinopelvic parameters acquired by a low-dose biplanar imaging system were evaluated among these groups.

RESULTS

Patients with more severe hip involvement were older and had longer disease duration and diagnostic delay, with lower Harris Hip Score (p < 0.001) and 12-item Short Form Health Survey Physical Component Score (p < 0.001) and higher Bath Ankylosing Spondylitis Disease Activity Index (p = 0.030) and Functional Index (p < 0.001). Patients with more severe hip involvement had significantly higher sacroiliac grade (p < 0.001) and higher modified Stoke Ankylosing Spondylitis Spinal Score (p < 0.001). Patients with moderate and severe hip involvement had similar lumbar lordosis and spino-sacral angle, whereas patients with severe hip involvement had lower pelvic tilt, pelvic femoral angle, higher sacral slope, and sagittal vertical axis.

CONCLUSIONS

The severity of hip involvement is associated with physical function and is not consistent with the severity of spinal involvement. Severe hip involvement impairs the ability to retrovert the pelvis to accommodate the sagittal deformity, and spinopelvic parameters should be concretely evaluated in preoperative counseling of patients with AS waiting for total hip arthroplasty. Key Points • The severity of hip involvement in patients with AS is associated with physical function. • Severe hip involvement impairs the ability to retrovert the pelvis to accommodate the sagittal deformity.

Posterior Pubic Incidence: A Novel Morphologic Spinopelvic Parameter Nearly Equal to Pelvic Incidence

BACKGROUND

Pelvic incidence (PI) and Jackson's angle are 2 major spinopelvic parameters that define the position of the sacrum within the pelvis. These parameters are measured on standing lateral radiography, and the identification of the hip axis is essential for measurements. Moreover, identifying the hip axis in patients with hip diseases or femoral head deformity is challenging. In this study, we described a novel parameter named posterior pubic incidence (PPI) that could be measured using the posterior pubic edge instead of the hip axis.

METHODS

Group A comprised 50 volunteers who underwent standing lateral lumbosacral radiography. Group B comprised 54 patients with abdominal or urologic problems who underwent supine computed tomography. The PI, pelvic tilt (PT), sacral slope, PPI, and posterior pubic tilt were measured. The differences between PI and PPI were evaluated. Linear regression analysis was used to predict the PI value from PPI.

RESULTS

The mean PI and PPI values were 47.41° ± 12.32° and 49.32° ± 11.94° in group A and 49.19° ± 9.99° and 49.99° ± 9.25° in group B, respectively. The mean absolute differences in groups A and B were 2.41° ± 1.63° and 1.9° ± 1.62°, respectively. High correlations were obtained between PI/PPI and pelvic tilt/posterior pubic tilt. PI could be calculated as PI° = PPI° - 2° on plain radiography and as PI° = PPI° - 1° on computed tomography.

CONCLUSIONS

PPI was strongly correlated with PI, which was nearly equal to PI, and may replace PI in formulas containing PI.

Elucidation of effect of spinopelvic parameters in degenerative disc disease

INTRODUCTION

This study aims to find out if there is any relationship between disc pathology and spinopelvic morphology, respectively.

METHODS

A total of 152 patients who complained about low back pain were assessed retrospectively. Patients were divided into three groups based on the presence of disc pathology: non-degenerative (ND) (n=34), degenerative disc disease (DDD) (n=80), and lumbar disc herniation (LDH) (n=38). Spinopelvic parameters were measured on the lateral standing radiographs using Surgimap® Software. The degree of degeneration of each disc was evaluated using T2-weighted images according to the Pfirmann classification. Correlation analyses were performed.

RESULTS

No significant difference was observed between the three groups in terms of sagittal spinal and pelvic parameters. Age and BMI were positively correlated with DDD and LDH. PI and proximal lombar lordosis (PLL) were the only effective variables in predicting DDD. PT and distal lumbar lordosis (DLL) were found to be effective variables in predicting LDH. PI and PT values in patients with L1, L2, and L3 DDD were statistically significantly higher than those without degeneration (P<0.05). Although there were no statistical differences between PI and PT values (P>0.05), DLL values in L4 and L5 DDD patients were significantly lower than those without degeneration (P=0.041; P=0.046; P<0.05).

CONCLUSIONS

The sagittal morphology of the spine directly influences the extent of lumbar disc degeneration. As the values of PI and PT increase, disc degeneration tends to occur at higher levels (L1-2-3). Disc degeneration at lower levels (L4-5) was associated with low DLL levels.

LEVEL OF EVIDENCE

Level III, retrospective study.

Lordosis loss in degenerative spinal conditions

PURPOSE

To establish whether common degenerative lumbar spine conditions have a predictable sagittal profile and associated range of lordosis. The spinopelvic balance of a normal population and normal ranges are well described in the literature. There is also evidence that certain degenerative conditions can lead to a preponderance of loss of lordosis at specific spinal levels. There is limited literature on the range and magnitude of loss of lordosis for known degenerative lumbar spine pathologies.

METHODS

A retrospective analysis of prospectively obtained radiographs from a dual surgeon database was performed and imaging analysed for spinopelvic parameters. Degenerative conditions studied were; Lumbar degenerative spondylolisthesis (L3/4 and L4/5 analysed separately), L5/S1 degenerative disc disease, L5/S1 isthmic spondylolisthesis. Pelvic incidence, sacral slope, pelvic tilt, segmental and global lumbar lordosis, vertebral lordosis and lumbar vertical axis were measured.

RESULTS

The range of change in segmental lordosis was normally distributed for all studied degenerative spinal conditions except L5/S1 isthmic spondylolisthesis. L5/S1 degenerative disc disease affected younger adults (mean age 37), whilst degenerative spondylolisthesis at L3/4 and L4/5 affected older adults (mean ages 69.5 and 68.9 respectively). Removing an outlying high-grade L5/S1 isthmic spondylolisthesis made the data distribution approach a normal distribution.

CONCLUSION

Most degenerative spinal pathologies cause a normally distributed spectrum of deformity which should be addressed and corrected with a tailored, individualised surgical plan for each patient. Universal treatment recommendations should be interpreted with caution.

The association between Roussouly sagittal alignment type and risk for adjacent segment degeneration following short-segment lumbar interbody fusion: a retrospective cohort study

Background

To date, the influence of Roussouly type on development of adjacent segment degeneration (ASD) after lumber fusion is still not fully explored, and the current study is aimed to evaluate the effect of Roussouly type on development of radiological ASD after single-level lumber fusion, and to compare the Roussouly types and spinopelvic parameters among those with different degenerative patterns of ASDs on sagittal plane.

Methods

A retrospective review of 288 patients underwent L4/5 or L5/S1 single-level posterior interbody fusions between January 2016 and December 2018 with a minimum 2-year follow up was performed. Radiological ASDs were identified and divided into 3 groups according to different degenerative patterns of the cephalad adjacent level on sagittal plane, including the types of retrolisthesis (Group A), anterolisthesis (Group B), and axial disc space narrowing (Group C). Roussouly types and radiological measurements were compared among three groups and potential risk factors for ASD were evaluated.

Results

Radiological ASD was found in 59 (20.5%) cases, in which patients with Roussouly type-2 was the most common. While, on subgroup analysis among three ASD groups, Roussouly type-1 occupied the highest proportion in Group A, differ in Group B and Group C, both with Type-2 as the most common. Moreover, Group A had significantly lower pelvic tilt (PT), larger sacral slope (SS), and larger segmental angle (SA) than Group B and Group C, which showed a more anteverted pelvic in Group A. Multivariate regression analysis noted Roussouly type, preoperative PT, and ∆PI-LL as the independent risk factors for radiological ASD.

Conclusion

Roussouly type was significantly associated with the development of radiological ASD; however, the Roussouly types and spinal pelvic parameters were varied among different sagittal degenerative patterns of ASD, which was important in restoring optimal lumbar sagittal alignments in initial surgery.

Risk factors for L5 pedicle fractures after single-level posterior spinal fusion

BACKGROUND CONTEXT

Pedicle fractures are a rare but potentially devastating complication of posterior instrumented spinal fusion (PSF). Preoperative awareness of the possible risk factors may help prevent these fractures by modifying the surgical plan. However, the risk factors have not yet been identified.

PURPOSE

To determine the preoperative parameters associated with postoperative L5 pedicle fracture after L4/5 PSF.

STUDY DESIGN

Case control study.

PATIENT SAMPLE

Patients undergoing L4/5 PSF at a single academic institution between 2014 and 2020.

OUTCOME MEASURES

Occurrence of postoperative L5 pedicle fracture.

METHODS

Of 253 patients (female:male, 145:108) undergoing L4/5 PSF from 2014 to 2020, patients with postoperative L5 pedicle fractures were identified retrospectively as "cases" (n = 8, all female, age: 70 ± 10.7 years). As a control group all remaining patients with a follow-up of more than 12 months were allocated (n = 184, 104 females, age: 64.27 ± 13.00 years). In all but 16 cases, anterior support with transforaminal or posterior interbody fusion was performed. Demographic and clinical data (body mass index (BMI)), surgical factors, and comorbidities) were compared. Radiological assessment of spinopelvic parameters was performed using pre- and postoperative standing lateral radiographs.

RESULTS

The overall incidence of L5 pedicle fractures after L4/5 spinal fusion was 3.16%, with a median time from index surgery to diagnosis of 25 days (range, 6-199 days) (75% within the first 32 days postoperatively). Patients with L5 pedicle fractures had higher pelvic incidence (PI) (71° ± 9° vs. 56° ± 11°; p=.001), sacral slope (SS) (45° ± 7° vs. 35° ± 8°; p=.002), L5 slope (30° ± 11° vs. 15° ± 10°, p=.001), L5 incidence (42° ± 14° vs. 26° ± 11°; p= .003), L1-S1 lumbar lordosis (LL) postop (57° ± 10° vs. 45° ± 11°; p=.006), and L4 -S1 LL postop (33° ± 7° vs. 28° ± 7°; p=.049) compared with the control group. Pelvic tilt and PI- LL mismatch were not significantly different. Female gender was a significant risk factor for L5 pedicle fractures (p=.015). BMI (kg/m²) was statistically equal in patients with or without pedicle fractures (28.37 ± 5.96 vs. 28.53 ± 16.32; p=.857). There was no significant difference between the groups for approximative bone mineral density assessment (Hounsfield units; 113 ± 60 vs. 120 ± 43; p=.396) using the L3 trabecular region of interest (ROI) measurement. The correlation analysis demonstrated that most of the identified risk factors except for the postoperative L4-S1 lordosis show significant positive associations among each other. All eight patients in the fracture group underwent revision surgery, and the instrumented fusion was extended to the sacrum, with the addition of sacral-alar-iliac or iliac screws, in six cases.

CONCLUSIONS

L5 pedicle fractures occurred in 3% of the patients after single level L4/5 PSF. Risk factors are female gender, higher PI, SS, L5 slope, L5 incidence, and LL postop but not high BMI. These findings can be used for surgical planning and decision of fusion levels.

Postoperative spinal alignment comparison of lateral versus supine patient position L5-S1 anterior lumbar interbody fusion

PURPOSE

Over the past decade, alternative patient positions for the treatment of the anterior lumbar spine have been explored in an effort to maximize the benefits of direct anterior column access while minimizing the inefficiencies of single or multiple intraoperative patient repositionings. The lateral technique allows for access from L1 to L5 through a retroperitoneal, muscle-splitting, transpsoas approach with placement of a large intervertebral spacer than can reliably improve segmental lordosis, though its inability to be used at L5-S1 limits its overall adoption, as L5-S1 is one of the most common levels treated and where high levels of lordosis are optimal. Recent developments in instrumentation and techniques for lateral-position treatment of the L5-S1 level with a modified anterior lumbar interbody fusion (ALIF) approach have expanded the lateral position to L5-S1, though the positional effect on L5-S1 lordosis is heretofore unreported. The purpose of this study was to compare local and regional alignment differences between ALIFs performed with the patient in the lateral (L-ALIF) versus supine position (S-ALIF).

METHODS

Retrospective, multi-center data and radiographs were collected from 476 consecutive patients who underwent L5-S1 L-ALIF (n = 316) or S-ALIF (n = 160) for degenerative lumbar conditions. Patients treated at L4-5 and above with other single-position interbody fusion and posterior fixation techniques were included in the analysis. Baseline patient characteristics were similar between the groups, though L-ALIF patients were slightly older (58 vs. 54 years), with a greater preoperative mean L5-S1 disk height (7.8 vs. 5.8 mm), and with less preoperative slip (6.6 vs. 8.5 mm), respectively. 262 patients were treated with only L-ALIF or S-ALIF at L5-S1 while the remaining 214 patients were treated with either L-ALIF or S-ALIF at L5-S1 along with fusions at other thoracolumbar levels. Lumbar lordosis (LL), L5-S1 segmental lordosis, L5-S1 disk space height, and slip reduction in L5-S1 spondylolisthesis were measured on preoperative and postoperative lateral X-ray images. LL was only compared between single-level ALIFs, given the variability of other procedures performed at the levels above L5-S1.

RESULTS

Mean pre- to postoperative L5-S1 segmental lordosis improved 39% (6.6°) and 31% (4.9°) in the L-ALIF and S-ALIF groups, respectively (p = 0.063). Mean L5-S1 disk height increased by 6.5 mm (89%) in the L-ALIF and 6.4 mm (110%) in the S-ALIF cohorts, (p = 0.650). Spondylolisthesis, in those patients with a preoperative slip, average reduction in the L-ALIF group was 1.5 mm and 2.2 mm in the S-ALIF group (p = 0.175). In patients treated only at L5-S1 with ALIF, mean segmental alignment improved significantly more in the L-ALIF compared to the S-ALIF cohort (7.8 vs. 5.4°, p = 0.035), while lumbar lordosis increased 4.1° and 3.6° in the respective groups (p = 0.648).

CONCLUSION

Use of the lateral patient position for L5-S1 ALIF, compared to traditional supine L5-S1 ALIF, resulted in at least equivalent alignment and radiographic outcomes, with significantly greater improvement in segmental lordosis in patients treated only at L5-S1. These data, from the largest lateral ALIF dataset reported to date, suggest that-radiographically-the lateral patient position can be considered as an alternative to traditional ALIF positional techniques.

Pelvic incidence significance relative to spinopelvic risk factors for total hip arthroplasty instability

AIMS

Pelvic incidence (PI) is a position-independent spinopelvic parameter traditionally used by spinal surgeons to determine spinal alignment. Its relevance to the arthroplasty surgeon in assessing patient risk for total hip arthroplasty (THA) instability preoperatively is unclear. This study was undertaken to investigate the significance of PI relative to other spinopelvic parameter risk factors for instability to help guide its clinical application.

METHODS

Retrospective analysis was performed of a multicentre THA database of 9,414 patients with preoperative imaging (dynamic spinopelvic radiographs and pelvic CT scans). Several spinopelvic parameter measurements were made by engineers using advanced software including sacral slope (SS), standing anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), lumbar lordosis (LL), and PI. Lumbar flexion (LF) was determined by change in LL between standing and flexed-seated lateral radiographs. Abnormal pelvic mobility was defined as ∆SPT ≥ 20° between standing and flexed-forward positions. Sagittal spinal deformity (SSD) was defined as PI-LL mismatch > 10°.

RESULTS

PI showed a positive correlation with parameters of SS, SPT, and LL (r-value range 0.468 to 0.661). Patients with a higher PI value showed higher degrees of standing LL, likely as a compensatory measure to maintain sagittal spine balance. There was a positive correlation between LL and LF such that patients with less standing LL had decreased LF (r = 0.49). Similarly, there was a positive correlation between increased SSD and decreased LF (r = 0.54). PI in isolation did not show any significant correlation with lumbar (r = 0.04) or pelvic mobility (r = 0.02). The majority of patients (range 89.4% to 94.2%) had normal lumbar and pelvic mobility regardless of the PI value.

CONCLUSION

The PI value alone is not indicative of either spinal or pelvic mobility, and thus in isolation may not be a risk factor for THA instability. Patients with SSD had higher rates of spinopelvic stiffness, which may be the mechanism by which PI relates to THA instability risk, but further clinical studies are required. Cite this article: Bone Joint J 2022;104-B(3):352-358.

The challenge of measuring spinopelvic parameters: inter-rater reliability before and after minimally invasive lumbar spondylodesis

BACKGROUND

The common manual measurement technique of spinal sagittal alignment on X-rays is susceptible to rater-dependent variability, which has not been adequately considered in previous publications. This study investigates the effect of those variations in the characterization of patients receiving lumbar spondylodesis.

METHODS

General alignment parameters on pre- and postoperative X-rays were evaluated by four raters in 43 prospectively sampled patients undergoing monolevel spondylodesis. The Intra-class Correlation Coefficient (ICC) for each rater pair and all raters together was calculated for inter-rater reliability. For the operation-induced change of the sagittal alignment in every patient the Wilcoxon test was applied to compare for each rater separately.

RESULTS

The ICCs were "good" (>0.75) to "excellent" (>0.9) for all raters together and for 45 of the 48 single rater pairs (93.75%). All revealed a significant increase of the addressed segmental lordosis and disc height and no significant change for spinopelvic parameters and sagittal vertical axis from pre- to postoperative. The lumbar lordosis showed a significant increase through the operation of +2.5° (p = 0.014) and +3.7° (p = 0.015) in two raters and no difference for the other ones (+2.1°, p = 0.171; -2.2°, p = 0.522).

CONCLUSIONS

The pre- to postoperative change of lumbar lordosis revealed different significance levels for different raters, although the ICCs were formally good. Accordingly, the evaluation by only one rater would lead to different conclusions. Due to this susceptibility of alignment measurements to rater-dependent variability, the exact evaluation process should be described in every publication and the consistency of significant results be validated through multiple raters.

TRIALS REGISTRATION

The trial was approved by the local ethics committee and listed at the national clinical trials register ( DRKS00004514 , date of registration: 08/11/2012).

The role of femoral obliquity angle and T1 pelvic angle in predicting quality of life after spinal surgery in adult spinal deformities

BACKGROUND

Adult spinal deformities (ASD) represent a growing clinical condition related to chronic pain, disability and reduction in quality of life (QoL). A strong correlation among spinal alignment, spinopelvic parameters and QoL after spinal fusion surgery in ASD patients was thoroughly investigated over the last decade, However, only few studies focused on the relationship between lumbo-pelvic-femoral parameters - such as Femoral Obliquity Angle (FOA), T1 Pelvic Angle (TPA) and QoL.

METHODS

Radiological and clinical data from 43 patients surgically treated with thoracolumbar posterior spinal fusion for ASD between 2015 and 2018 were retrospectively analyzed. The primary outcomes were the correlation between preoperative spino-pelvic-femoral parameters and postoperative clinical, functional outcomes and QoL. Secondary outcomes were: changes in sagittal radiographic parameters spino-pelvic-femoral, clinical and functional outcomes and the rate of complications after surgery.

RESULTS

Using Spearman's rank correlation coefficients, spinopelvic femoral parameters (FOA, TPA, pre and post-operative) are directly statistically correlated to the quality of life (ODI, SRS-22, pre and post-operative; > 0,6 strong correlation, p <  0.05). Stratifying the patients according pre preoperative FOA value (High FOA ≥ 10 and Normal/Low FOA <  10), those belonging to the first group showed worse clinical (VAS: 5.2 +/- 1.4 vs 2.9 +/- 0.8) and functional outcomes (ODI: 35.6+/- 6.8 vs 23.2 +/- 6.5) after 2 years of follow-up and a greater number of mechanical complications (57.9% vs 8.3% p <  0.0021).

CONCLUSION

Based on our results, preoperative FOA and TPA could be important prognostic parameters for predicting disability and quality of life after spinal surgery in ASD patients and early indicators of possible spinal sagittal malalignment. FOA and TPA, like other and better known spinopelvic parameters, should always be considered when planning corrective surgery in ASD patients.

Determining the validity and reliability of spinopelvic parameters through comparing standing whole spinal radiographs and upright computed tomography images

Background

Standing whole spinal radiographs are used to evaluate spinal alignment in adult spinal deformity (ASD), yet some studies have reported that pelvic incidence, pelvic tilt, and thoracic kyphosis (TK) intra- and inter-observer reliability is low. This study aimed to evaluate the accuracy of spinopelvic parameters through comparing standing whole spinal radiographs and upright CT images.

Methods

We enrolled 26 patients with ASD. All standing whole spinal posterior/anterior and lateral radiographs and upright whole spinal CT had been obtained in a natural standing position. Two examiners independently measured 13 radiographic parameters. Interclass correlation coefficients (ICCs) were used to analyze measurement intra- and inter-observer reliability. Paired t- and Pearson’s correlation tests were used to analyze validity of the standing whole spinal radiographs.

Results

ICCs of upright CT were excellent in both intra- and inter-observer reliability. However, intra-observer ICCs for TK2–12, TK1–5, TK2–5, and TK5–12 on standing lateral radiographs were relatively low, as were inter-observer ICCs for TK2–12, TK1–5, TK2–5, and TK5–12. Concerning TK values, the difference between the radiographs and CT in TK1–12 and TK2–12 were 4.4 ± 3.1 and 6.6 ± 4.6, respectively, and TK values from T2 showed greater measurement error (p < 0.05).

Conclusions

Upright CT showed excellent intra- and inter-observer reliability in the measurement of spinopelvic parameters. Measurement of TK with T2 on standing whole spinal radiographs resulted in a greater measurement error of up to 6.6°. Surgeons need to consider this when planning surgery and measuring postoperative TK changes in patients with ASD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04786-5.

The Influences of Spinopelvic Parameters and Associated Factors on Development of Proximal Instrumented Fracture After Posterior Instrumentation

OBJECTIVE

To investigate influences of spinopelvic parameters, such as lumbar lordosis (LL) angles, pelvic incidence, sacral slope, pelvic tilt, and sagittal vertical axis, on development of the proximal junctional failure fracture type after posterior instrumentation.

METHODS

This retrospective 1:3 matched case-control cohort study included 24 patients who developed proximal instrumented fracture in the study group and 72 patients without proximal junctional failure in the control group. Weighted Charlson Comorbidity Index and bone mineral density with T-score were recorded. In addition to spinopelvic parameters, proximal local kyphosis (PLK), which refers to a kyphosis angle between the upper end plate of upper instrumented vertebra plus 1 level and the lower end plate of upper instrumented vertebra; pelvic incidence-LL mismatch; and spinopelvic realignment score were calculated.

RESULTS

More comorbidities (Charlson Comorbidity Index, P = 0.002) and poorer bone density (T-score, P = 0.001) were noted in the study group. Before surgery, the study group had significantly lower LL (P = 0.046) and sacral slope (P = 0.043) and significantly higher PLK (P < 0.001) and pelvic tilt (P = 0.044) than the control group. Postoperatively, the study group had significantly higher PLK (P < 0.001) and lower LL (P = 0.031) than the control group; the degree of pelvic incidence-LL mismatch (P = 0.007) remained significantly higher in the study group. Preoperative (P = 0.026) and postoperative (P = 0.045) spinopelvic realignment scores was worse in the study group. Multivariate analysis revealed that postoperative PLK was the most significant radiographic factor to predict proximal instrumented fracture (P = 0.002, odds ratio 1.140, 95% confidence interval).

CONCLUSIONS

In our experience, appropriate LL and lower PLK should be obtained at surgery to prevent development of instrumented fracture.

Use of iliac screw associated with more correction of lumbar lordosis than S2-alar-iliac screw for adult spinal deformity

Background

To date, there is a paucity of reports clarifying the change of spinopelvic parameters in patients with adult spinal deformity (ASD) who underwent long segment spinal fusion using iliac screw (IS) and S2-alar-iliac screw (S2AI) fixation.

Methods

A retrospective review of consecutive patients who underwent deformity correction surgery for ASD between 2013 and 2017 was performed. Patients were divided into two groups based on whether IS or S2AI fixation was performed. All radiographic parameters were measured preoperatively, immediately postoperatively, and the last follow-up. Demographics, intraoperative and clinical data were analyzed between the two groups. Additionally, the cohort was subdivided according to the postoperative change in pelvic incidence (PI): subgroup (C) was defined as change in PI ≥5° and subgroup (NC) with change < 5°. In subgroup analyses, the 2 different types of postoperative change of PI were directly compared.

Results

A total of 142 patients met inclusion criteria: 111 who received IS and 31 received S2AI fixation. The IS group (65.6 ± 26°, 39.8 ± 13.8°) showed a significantly higher change in lumbar lordosis (LL) and upper lumbar lordosis (ULL) than the S2AI group (54.4 ± 17.9°, 30.3 ± 9.9°) (p < 0.05). In subgroup (C), PI significantly increased from 53° preoperatively to 59° postoperatively at least 50% of IS cohort, with a mean change of 5.8° (p < 0.05). The clinical outcomes at the last follow-up were significantly better in IS group than in S2AI group in terms of VAS scores for back and leg. The occurrence of sacroiliac joint pain and pelvic screw fracture were significantly greater in S2AI group than in IS group (25.8% vs 9%, p < 0.05) and (16.1% vs 3.6%, p < 0.05).

Conclusions

Compared with the S2AI technique, the IS technique usable larger cantilever force demonstrated more correction of lumbar lordosis, and possible increase in pelvic incidence. Further study is warranted to clarify the clinical impaction of these results.

Efficacy of lateral lumbar interbody fusion combined with posterior spinal fusion compared with three-column osteotomy for adult spinal deformity with severe lumbar sagittal deformity

PURPOSE

The clinical and radiological results of adult spinal deformity (ASD) patients with a severe lumbar sagittal deformity undergoing multilevel lateral lumbar interbody fusion (LLIF) + posterior spinal fusion (PSF) were compared to patients undergoing three-column osteotomy (3CO).

METHODS

We defined severe lumbar sagittal deformity as fulcrum backward bending (FBB) pelvic incidence minus lumbar lordosis (PI-LL) ≧ 20 degrees. A total of twenty-five patients with an ASD were enrolled between 2013 and 2018. Fifteen patients were in the LLIF + PSF group, and ten patients were in the 3CO group. We evaluated patient demographics, clinical outcomes, and radiographic parameters such as the Cobb angle and spinopelvic parameters from standing X-ray films in each group.

RESULTS

The LLIF + PSF group had a significantly shorter follow-up time than the 3CO group. Postoperatively, the LLIF + PSF group had significantly lower PI-LL and a shorter sagittal vertical axis than the 3CO group. Postoperative PI-LL changes in the LLIF + PSF group were significantly smaller than those in the 3CO group. There were no differences in other patient demographics, radiographic parameters, or clinical outcomes between the groups.

CONCLUSION

Multilevel LLIF + PSF improved the PI-LL and SVA more than did 3CO for ASD patients with severe lumbar sagittal deformity. This indicated that the multilevel LLIF with open PSF can provide good clinical outcomes even in cases with severe lumbar sagittal deformity such as large FBB PI-LL in which 3CO techniques usually are needed.

Sagittal Balance, Pulmonary Function, and Spinopelvic Parameters in Severe Post-Tubercular Thoracic Kyphosis

Study Design

Cross-sectional study.

Purpose

To evaluate sagittal balance, pulmonary function, and spinopelvic parameters in patients with healed spinal tuberculosis with severe thoracic kyphosis.

Overview of Literature

Deterioration of neurological function is an absolute indication of surgical intervention in severe post-tubercular kyphosis, but the relationship of compromise in lung function and spinal alignment with severity of kyphosis is still unclear.

Methods

Twenty patients (age, 14–60 years) with healed spinal tuberculosis with thoracic kyphosis >50° were included. Lateral-view radiography of the whole spine, including both hips, was performed for assessment of kyphotic angle (K angle), sagittal balance, lumbar lordosis, and spinopelvic parameters. Pulmonary function was assessed by measuring the forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and their ratio (FEV1/FVC) by spirometry.

Results

A positive correlation between severity of kyphosis and sagittal imbalance was noted, with compensatory mechanisms maintaining the sagittal balance in only up to 80° of dorsal kyphosis. In >80° of kyphosis, FVC was found to be markedly decreased (mean FVC=50.6%). The mean K angle was lower in subjects with lower thoracic kyphosis. In lower thoracic kyphosis, due to short lordotic and long kyphotic curves, both lumbar lordosis and pelvic retroversion worked at compensation, whereas, in middle thoracic kyphosis, due to long lordotic curve, only lumbar lordosis was required. Normal pulmonary function (mean FVC, 83.0%) and lesser kyphotic deformity (mean K angle in adolescents, 69.8°; in adults, 94.4°) were found in adolescents.

Conclusions

In >80° of thoracic kyphosis, there is sagittal imbalance and a markedly affected pulmonary function. Such patients should be offered corrective surgery if they are symptomatic and medically fit to undergo the procedure. However, whether the surgical procedure would result in improved pulmonary function and sagittal balance needs to be evaluated by a follow-up study.

Novel Lateral Approach for MIS Sacroiliac Joint Arthrodesis: An Assessment of Feasibility and Outcomes

OBJECTIVE

The prevalence of physicians experiencing work-related musculoskeletal disorders is high. Traditionally, minimally invasive surgery (MIS) sacroiliac joint (SIJ) fusions are performed with the patient oriented in the prone position, with an incision made inferior to the iliac crest. However, a novel technique that orients the patient in the lateral decubitus position has the potential of significantly enhancing ergonomics and ease of approach. The primary objectives of this study were to quantify surgical parameters, describe this 'lateral-decubitus MIS' technique, and identify imaging angle parameters that predict feasibility.

METHODS

A prospective cohort of patients who underwent MIS SIJ arthrodesis in the lateral decubitus position was evaluated at a single institution between 2017 and 2020. Medians and ranges of intraoperative blood loss, operative time, revision rate, infection, and total radiation dose were recorded. Sacral inlet and outlet angles were defined and collected to assess for operative candidacy.

RESULTS

Thirty-nine cases were identified in 34 patients who underwent the technique with an age range of 31-78 years. Median blood loss was 22.5 mL, operating room time was 32.5 minutes, and radiation dose was 30.9 rads. Average sacral inlet was 24.51° and average sacral outlet was 65.44°. Median length of stay was 0.94 days. No cases were aborted or required revision. A total of 93% of study participants reported improvement in pain. Operative parameters were comparable to the traditional prone approach.

CONCLUSIONS

The aim was to provide an insight into outcomes and metrics observed from pioneering this style of procedure. A future study comparing traditional perioperative parameters together with surgical ergonomics is needed.

Analysis of sagittal profile and radiographic parameters in symptomatic thoracolumbar disc herniation patients

BACKGROUND

Few studies describe thoracolumbar disc herniation (TLDH) as an isolated category, it is frequently classified as the lower thoracic spine or upper lumbar spine. Thus, less is known about the morphology and aetiology of TLDH compared to lumbar disc herniation (LDH). The aim of study is to investigate sagittal alignment in TLDH and analyze sagittal profile with radiographic parameters.

METHODS

Data from 70 patients diagnosed with TLDH were retrospectively reviewed. The thoracic-lumbar alignment was depicted by description of curvatures (the apex of lumbar curvature, the apex of thoracic curvature, and inflexion point of the two curvatures) and radiographic parameters from complete standing long-cassette spine radiographs. The rank sum test was utilised to compare radiographic parameter values in each subtype.

RESULTS

We found two subtypes differentiated by the apex of thoracic kyphotic curves. The sagittal profile was similar to that of the normal population in type I, presenting the apex of the thoracic kyphotic curve located in the middle thoracic spine. The well aligned thoracic-lumbar curve was disrupted in type II, presenting the apex of the thoracic kyphotic curve located in the thoracolumbar region in type II patients. Thirty-six patients were classified as type I, and 34 patients were classified as type II. The mean sagittal vertical axis, T1 pelvic angle and L1 pelvic angle were 27.9 ± 24.8°, 8.2 ± 7.3° and 6.2 ± 4.9°, respectively. There was significant difference (p < 0.001) of thoracolumbar angle between type I (14.9 ± 7.9°) and type II patients (29.1 ± 13.7°).

CONCLUSIONS

We presented two distinctive sagittal profiles in TLDH patients, and a regional kyphotic deformity with a balanced spine was validated in both subtypes. In type I patients, disc degeneration was accelerated by regional kyphosis in the thoracolumbar junction and eventually caused disc herniation. In type II patients, excessive mechanical stress was directly loaded at the top of the curve (thoracolumbar apex region) rather than being diverted by an arc as in a normal population or type I patients. Mismatch between shape and sacral slope value was observed, and better agreement was found in Type II patients.

The effect of pedicle subtraction osteotomy for the correction of severe Scheuermann thoracolumbar kyphosis on sagittal spinopelvic alignment

Purpose

To analyze how pedicle subtraction osteotomy (PSO) treatment of severe Scheuermann thoracolumbar kyphosis (STLK) using pedicle screw instrumentation affects sagittal spinopelvic parameters.

Background

The medical literature on the post-surgical effects of treatments such as Ponte osteotomy is limited, but suggests few effects on spinopelvic profiles. Currently, there is no research regarding changes in sagittal spinopelvic alignment upon PSO treatment in STLK patients.

Methods

We performed a retrospective study on 11 patients with severe STLK. These patients underwent posterior-only correction surgeries with PSO and pedicle screw instrumentation between 2012 to 2017 in a single institute. Patients were measured for the following spinopelvic parameters: global kyphosis (GK), thoracic kyphosis (TK), thoracolumbar kyphosis (TL), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tile (PT), sacral slope (SS), and administered a Scoliosis Research Society-22 questionnaire (SRS-22) pre-operation, post-operation and at final follow-up.

Results

GK improved from a median of 74.1° to 40.0° after surgery, achieving a correction rate of 48.8% with a median correction loss of 0.8°. TK, TL and LL all showed significant difference (P < 0.05) and SVA improved 22.7 (11.6, 30.9) mm post operation. No significant difference was found in pelvic parameters (PI, PT, SS, all P < 0.05). The absolute value of LL- PI significantly improved from a median of 26.5° pre-operation to 6.1° at the final follow-up. 72.7% in this series showed an evident trend of thoracic and lumbar apices migrating closer to ideal physiological segments after surgery. Self-reported scores of pain, self-image, and mental health from SRS-22 revealed significant improvement at final follow-up (all P < 0.05).

Conclusions

PSO treatment of severe STLK with pedicle screw instrumentation can improve spine alignment and help obtain a proper alignment of the spine and the pelvis.

The surgical treatment of severe Scheuermann's kyphosis

AIMS

To report the surgical outcome of patients with severe Scheuermann's kyphosis treated using a consistent technique and perioperative management.

METHODS

We reviewed 88 consecutive patients with a severe Scheuermann's kyphosis who had undergone posterior spinal fusion with closing wedge osteotomies and hybrid instrumentation. There were 55 males and 33 females with a mean age of 15.9 years (12.0 to 24.7) at the time of surgery. We recorded their demographics, spinopelvic parameters, surgical correction, and perioperative data, and assessed the impact of surgical complications on outcome using the Scoliosis Research Society (SRS)-22 questionnaire.

RESULTS

The mean follow-up was 8.4 years (2 to 14.9). There were 85 patients (96.6%) with a thoracic deformity. Posterior spinal fusion with closing-wedge osteotomies and hybrid instrumentation was used in 86 patients; two patients underwent combined anterior and posterior spinal fusion. The mean kyphosis was corrected from 94.5° to 47.5° (p < 0.001). Coronal and sagittal balance returned to normal. The rate of complications was 12.5%: there were no neurological deficits, implant failure, or revision surgery. SRS-22 scores improved from a mean 3.6 (1.3 to 4.1) to 4.6 (4.2 to 5.0) at two years (p < 0.001) with a high rate of patient satisfaction. Non-smokers and patients with lower preoperative SRS-22 scores showed greater improvement in their quality of life. Sagittal pelvic balance did not change after correction of the kyphosis and correlated with lumbar lordosis but not with thoracic or thoracolumbar kyphosis.

CONCLUSION

Posterior spinal fusion using hybrid instrumentation, closing-wedge osteotomies, and iliac bone grafting achieves satisfactory correction of a severe kyphosis resulting in improvements in physical and mental health and a high degree of patient-reported satisfaction. Cite this article: Bone Joint J 2021;103-B(1):148-156.

Revision Surgery Rates After Minimally Invasive Adult Spinal Deformity Surgery: Correlation with Roussouly Spine Type at 2-Year Follow-Up?

BACKGROUND

Spinopelvic parameters have hitherto dictated much of adult spinal deformity (ASD) correction. The Roussouly classification is used for the normal adult spine. We evaluated whether a correlation would be found between the Roussouly type and the rate of revision surgery in patients with ASD undergoing circumferential minimally invasive spinal (cMIS) correction.

METHODS

A multicenter retrospective review of patients who had undergone cMIS surgery for ASD was performed. The inclusion criteria were age ≥18 years and 1 of the following: coronal Cobb angle >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, pelvic incidence (PI) to lumbar lordosis (LL) mismatch >10°, cMIS surgery, and a minimum of 2 years of follow-up data available. The patients were classified by Roussouly type, and the clinical and radiographic outcomes were evaluated.

RESULTS

A total of 104 patients were included in the present analysis. Of the 104 patients, 41 had Roussouly type 1, 32 had type 2, 23 had type 3, and 8 had type 4. Preoperatively, the patients with type 4 had the highest PI (P = 0.002) and LL (P < 0.001). Postoperatively, the PI-LL mismatch, Cobb angle, and sagittal vertical axis were not different among the 4 groups. However, the patients with type 2 had had the highest rate of complications (type 1, 29.3%; type 2, 61.3%; type 3, 34.8%; type 4, 25.0%; P = 0.031). The reoperation rates were comparable (type 1, 19.5%; type 2, 38.7%; type 3, 13.0%; type 4, 12.5%; P = 0.097). The reoperation rates for adjacent segment degeneration or proximal junctional kyphosis were also comparable (P = 0.204 and P = 0.060, respectively).

CONCLUSIONS

We did not find a clear correlation between Roussouly type and the rate of revision surgery for adjacent segment disease or proximal junctional kyphosis in patients who had undergone cMIS surgery for ASD.

Reduction of spondylolisthesis and sagittal balance correction by anterior lumbar interbody fusion (ALIF)

PURPOSE

Long time recognized as a cause of lumbar stenosis, degenerative spondylolisthesis has an evolution in interrelation with sagittal balance. This study aimed to assess the role of ALIF in correcting the sagittal balance in patients with degenerative spondylolisthesis.

MATERIAL AND METHODS

Twenty patients aged between 47 and 70 years were operated between July 2011 and September 2014 for degenerative spondylolisthesis by ALIF. The pre-operative and post-operative valid standing full spine radiographs were reviewed retrospectively. Clinical and radiological evaluations were conducted pre-operatively and postoperatively at one year and five years.

RESULTS

Lumbar lordosis (LL) was measured to 41.16 ± 14.25° pre-operatively and 47.27 ± 11.25° post-operatively (p > 0.05). At one year was 49.76 ± 13.31° and at five years 46.93 ± 9.26° (p > 0.05). Mean gain of lordosis after ALIF at index level was calculated to 8 ± 1.6° [4-12°].

CONCLUSIONS

ALIF offers a good reduction of the slipped vertebra providing good conditions for fusion and is an efficient surgical technique to recreate the sagittal spine balance.

ALIF in the correction of spinal sagittal misalignment. A systematic review of literature

PURPOSE

We aim at analysing the impact of anterior lumbar interbody fusion (ALIF) in restoring the main spinopelvic parameters, along with its potentials and limitations in correcting sagittal imbalance.

MATERIALS AND METHODS

The 2009 PRISMA flow chart was used to systematically review the literature; 27 papers were eventually selected. The following spinopelvic parameters were observed: pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), segmental lumbar lordosis (LLseg) and sagittal vertical axis (SVA). Papers reporting on hyperlordotic cages (HLC) were analysed separately. The indirect decompression potential of ALIF was also assessed. The clinical outcome was obtained by collecting visual analogue scale (VAS) for back and leg pain and Oswestry Disability Index (ODI) scores. Global fusion rate and main complications were collected.

RESULTS

PT, SS, LL, LLseg and SVA spinopelvic parameters all improved postoperatively by - 4.3 ± 5.2°, 3.9 ± 4.5°, 10.6 ± 12.5°, 6.7 ± 3.5° and 51.1 ± 44.8 mm, respectively. HLC were statistically more effective in restoring LL and LLseg (p < 0.05). Postoperative disc height, anterior disc height, posterior disc height and foraminal height, respectively, increased by 58.5%, 87.2%, 80.9% and 18.1%. Postoperative improvements were observed in VAS back and leg and ODI scores (p < 0.05). The global fusion rate was 94.5 ± 5.5%; the overall complication rate was 13%.

CONCLUSION

When managing sagittal imbalance, ALIF can be considered as a valid technique to achieve the correct spinopelvic parameters based on preoperative planning. This technique permits to obtain an optimal LL distribution and a solid anterior column support, with lower complications and higher fusion rates when compared to posterior osteotomies.

Lumbar spinal fusion of low-grade degenerative spondylolisthesis (Meyerding grade I and II): Do reduction and correction of the radiological sagittal parameters correlate with better clinical outcome?

INTRODUCTION

Lumbar and lumbosacral spinal fusion is an established procedure for the treatment of degenerative spondylolisthesis. However, the impact of reduction in the affected segment and of improvement in the radiological sagittal parameters on the clinical outcome remains unclear. Purpose of the study is to analyze the correlation between the radiological sagittal parameters and clinical outcome after lumbar spinal fusion in low-grade degenerative spondylolisthesis.

MATERIALS AND METHODS

In a monocentric prospective, clinical study, patients with low-grade degenerative spondylolisthesis of a single lumbar segment have been included. All patients received a lumbar spinal fusion according to the pathology of the treated segment. Patients attended clinical and radiological follow-up examination 1 and 2 years postoperatively. Clinical outcome was assessed using the Core Outcome Measurement Index (COMI), the Oswestry Disability Index (ODI) and the EuroQol 5D. The sagittal spinopelvic radiological parameters, sagittal rotation and anterior displacement of the affected segment and lumbar lordosis were assessed. The correlation between the sagittal radiological parameters and clinical outcome was analyzed using Spearman-Rho bi-serial test.

RESULTS

Sixty-two patients (35 female and 27 male) with an average age of 59.3 years were included in the study. All patients completed the follow-up examinations. Significant improvement in COMI, ODI and EuroQol 5D scores was shown in all follow-up examinations. Significant reduction in the anterior displacement was measured postoperatively, which was preserved during the follow-up. However, no correlation could be demonstrated between reduction in anterior displacement and improvement in clinical outcome. Nonetheless, correlation between correction of sagittal rotation and clinical outcome was shown.

CONCLUSIONS

Reduction in anterior displacement of the affected segment in the surgical treatment of low-grade degenerative spondylolisthesis does not have an impact on the clinical outcome.

Pelvic incidence in a femoroacetabular impingement population

Objective

We aim to determine if pelvic incidence (PI) differed between a symptomatic femoroacetabular impingement (FAI) population and a control.

Methods

We retrospectively identified a cohort of symptomatic FAI patients and compared measured PI to a control group.

Results

The PI was significantly lower in the FAI group compared to the control (51.32±1.07 vs. 55.63±1.04; P < 0.01).

Conclusion

The mean PI was significantly decreased in the FAI population compared to a control.

The Influence of Mechanic Factors in Disc Degeneration Disease as a Determinant for Surgical Indication

OBJECTIVE

Low back pain is the most common reason for physician visit in Western population. It's one of the factors that affect health-related quality of life. Intervertebral disc degeneration is one of the leading factors for low back pain and disc degeneration needs serious attention. In this article, we try to summarize biomechanical factors on the degenerative process.

METHODS

Patients with low back pain in Neurosurgery Department between January 2012 and June 2019 are searched for this study. The patients were gathered under 2 groups; surgical intervention and conservative treatment groups. Intervertebral disc degeneration was assessed by Pfirrmann grading system. All spinopelvic parameters were measured by using standardized lateral plain standing lumbar radiographs.

RESULTS

There were 165 patients in the surgical group (60 females, 105 males) and 84 patients in the conservative group (57 females, 27 males) after randomization. One hundred fifty patients had microdiscectomy and 15 patients had spinal instrumentation with transforaminal lumbar interbody fusion. There was not a statistically significant difference between surgical intervention and conservative treatment groups when comparing disc degeneration status. There was a statistically significant difference in parameters lumbar lordosis (LL), L4-S1, and pelvic incidence-LL (PI-LL) between the 2 treatment groups. In the surgical group when we further analyze the spinopelvic parameters in between the 2 different surgical techniques; L4-S1, pelvic tilt, and PI-LL showed a statistically significant difference.

CONCLUSION

Degenerative disc disease is related with multiple factors which can be detailed under the mechanic components and the genetic components. Of these factors, spinopelvic parameters seem highly penetrating to patients' surgery needs with degenerative disc disease independently.

[Effect of posterior osteotomy on the sagittal parameters of the spinopelvis in patients with lumbar degenerative kyphosis]

OBJECTIVE

To investigate the influence of posterior osteotomy on spinopelvic parameters in lumbar degenerative kyphosis (LDK) patients.

METHODS

The clinical data of 21 patients with lumbar degenerative kyphosis who underwent osteotomy from January 2012 to December 2015 were retrospectively analyzed. There were 5 males and 16 females, aged from 55 to 76 years with an average of (66.24±5.13) years. All patients had taken preoperative and postoperative full length spinal X-ray, analyzing the spinopelvic parameters as thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS).

RESULTS

All operations were successful, the average operative time was 190 min (160 to 220 min) and intraoperative blood loss was 1 000 ml (800 to 1900 ml). Parameters of the patients between preoperative and period 1-year follow-up were as follows : preoperative TK increased from (31.67±21.13) ° to (34.67±11.60) °, LL corrected from (4.76±3.17) ° to (37.41±6.28) °, PT reduced from (33.94±5.01) ° to (20.12±5.36) °, and SS improved from (18.47±2.60) ° to (31.71±4.30) °, SVA restored from (13.24±3.60) cm to (2.82±1.33) cm. There were significant differences of spinopelvic parameters between preoperation and postoperation (P<0.05).

CONCLUSION

Posterior osteotomy can effectively reconstruct the sagittal balance of spinopelvis in patients with lumbar degenerative kyphosis. The recovery of lumbar lordosis and sacral slope is closely related to the reconstruction of sagittal balance.

Measurement of spinopelvic parameters in healthy adults of Indian origin - A cross sectional study

BACKGROUND

Restoration of spinopelvic balance during spinal surgery is very important to ensure a good outcome. Many studies have been conducted to define the normal ranges, examining the correlation between these individual parameters and their relation with spinal parameters of thoracic kyphosis and lumbar lordosis. The ranges, specific to individual ethnicities, is very essential to restore the sagittal balance in patients suffering from spinal degenerative conditions. Hence this study aims to define the average ranges of relevant spinopelvic parameters in the adult population of Indian origin.

METHODS

A observational cross sectional study was conducted in 130 healthy volunteers in Mumbai without having any spine, hip or pelvis pathology. Spinopelvic parameters like Pelvic Incidence(PI), Sacral Slope(SS) and Pelvic Tilt(PT) were studied and compared between various other similar studies with patients of different ethnicities. The correlation of those parameters with each other was also evaluated.

RESULTS

The mean value of PI was 51.50(±6.85°), that of SS was 39.17° (±6.26°) and for PT it was 12.32°(±5.41°). These values were statistically significant between both sexes for PI and PT. The strongest positive correlation among the parameters was between pelvic incidence and sacral slope, with a r-value of 0.668. Comparison of our study with similar studies within the country (Chennai, Delhi and Surat) showed statistically significant differences in PT and SS of all three studies while PI was not significant when compared with the Surat study.

CONCLUSION

There appears to be considerable variation of the values of the spinopelvic parameters as determined by various studies due to ethnic variations. Further studies should be done with larger samples and directed towards early detection of individuals at risk of developing degenerative spinal disorders with sagittal imbalance, so that interventions can be made at an earlier stage.

Fusion technique does not affect short-term patient-reported outcomes for lumbar degenerative disease

BACKGROUND/CONTEXT

Degenerative lumbar disease can be addressed via an anterior or posterior approach, and with or without the use of an interbody cage. Although several studies have compared the type of approach and technique, there is a lack of literature assessing patient-reported outcome measures (PROMs) and radiographic parameters between different fusion techniques.

PURPOSE

To determine whether the surgical approach and fusion technique for lumbar degenerative disease had an effect on short-term PROMs and radiographic parameters.

STUDY DESIGN/SETTING

Retrospective Cohort Study.

PATIENT SAMPLE

Three hundred and ninety-one patients who underwent a 1-3 level lumbar spine fusion procedure at a high-volume academic center were retrospectively identified. Patients were divided into three groups based on the type of fusion they underwent: posterolateral fusion (PLF), anterior lumbar interbody fusion (ALIF), or transforaminal lumbar interbody fusion (TLIF).

OUTCOME MEASURES

PROMs: Short Form-12 (SF-12) Physical Component Score (PCS) and Mental Component Score (MCS), Oswestry Disability Index (ODI), Visual Analog Score (VAS) Back, VAS Leg. Spinopelvic measurements: Pelvic Tilt (PT), Sacral Slope (SS), Pelvic Incidence (PI), Lumbar Lordosis (LL), Segmental Lordosis (SL), PI-LL mismatch.

METHODS

Patients with less than 1-year follow-up were excluded from the cohort. Pre- and postoperative spinopelvic measurements were obtained for all patients. Univariate analysis (Chi-squared/Fisher's exact test or ANOVA test with post-hoc Bonferroni test) was used to compare among the three groups in the PROMs and radiographic spinopelvic parameters. Multiple linear regression was used to determine if fusion technique was an independent predictor of change in each patient outcome.

RESULTS

Two hundred and sixteen patients were included in the PLF group, 33 patients in the ALIF group, and 142 patients in the TLIF group. The PLF group was significantly older at baseline (p<.001) and had lower preoperative diagnosis rates of degenerative scoliosis and disc herniations (p<.001), whereas the ALIF group underwent a higher proportion of three-level fusions (p<.001). There was no significant difference in spinopelvic parameters preoperatively, however the ALIF group showed significantly more improvement in SL postoperatively (p=.004) than the PLF and TLIF groups. Within each group, SL improved for the PLF and ALIF groups (p=.002 for both), but not for the TLIF group (p=.238). Comparing patient outcomes, the ALIF group reported lower preoperative VAS Leg scores (p=.031), however, this difference resolved postoperatively. Stratifying for preoperative diagnosis, there were no significant differences in outcomes, except for a greater improvement in VAS Leg scores for degenerative scoliosis patients undergoing ALIF. Using multivariate analysis, fusion technique was not found to be a significant predictor of change in any patient outcome or in odds of revision.

CONCLUSIONS

Lumbar degenerative disease can be treated with several different fusion techniques, however, the relationship between type of fusion and PROMs is not established. Based on the findings in this study, the ALIF group showed greater improvement in SL compared with the PLF and TLIF groups, however, there was no difference noted in overall LL, PI-LL mismatch or other spinopelvic parameters. Despite these radiographic findings, patient outcome measures remained similar between all three fusion types.

Importance of Spinal Alignment in Primary and Metastatic Spine Tumors

Spinal alignment, particularly with respect to spinopelvic parameters, is highly correlated with morbidity and health-related quality-of-life outcomes. Although the importance of spinal alignment has been emphasized in the deformity literature, spinopelvic parameters have not been considered in the context of spine oncology. Because the aim of oncologic spine surgery is mostly palliative, consideration of spinopelvic parameters could improve postoperative outcomes in both the primary and metastatic tumor population by taking overall vertebral stability into account. This review highlights the relevance of focal and global spinal alignment, particularly related to spinopelvic parameters, in the treatment of spine tumors.

Minimally Invasive Advances in Deformity

Adult spinal deformity is a major contributor to pain and disability. It is a degenerative disease with a rigid spine. Spinopelvic parameters have been identified that outline goals of operative intervention, as they have shown to significantly improve patient outcomes. Previously, this was accomplished with large, open fusions. Unfortunately, the adult spinal deformity population is often elderly with significant comorbidities. These extensive fusions have a high rate of morbidity and mortality. Technological advances have allowed minimally invasive approaches to be developed. These techniques have decreased operative morbidity without increasing health care spending.

Comparison of the Effects of Magnetically Controlled Growing Rod and Tradiotinal Growing Rod Techniques on the Sagittal Plane in the Treatment of Early-Onset Scoliosis

Objective

Comparing the effects of magnetically controlled growing rod (MCGR) and traditional growing rod (TGR) techniques on the sagittal plane in the treatment of early-onset scoliosis (EOS).

Methods

Twelve patients were operated using dual MCGR technique in one center, while 15 patients were operated using dual TGR technique for EOS in another center. Patients’ demographic characteristics, complications and radiological measurements such as cobb angle, thoracic kyphosis, lumbar lordosis, T1–S1 range (mm), proximal junctional angle, distal junctional angle, sagittal balance, coronal balance, pelvic incidence, sacral slope and pelvic tilt were assessed and compared in preoperative, postoperative and last follow-up period.

Results

Age and sex distributions were similar in both groups. The mean number of lengthening in the MCGR group was 12 (8–15) and 4.8 (3–7) in the TGR group. Two techniques were shown to be effective in controlling the curvature and in the increase of T1–S1 distance. In TGR group, four patients had rod fractures, six patients had screw pull-out and four patients had an infection, whereas three patients had screw pull-out and one patient had infection complications in the MCGR group.

Conclusion

There was no significant difference between the two groups in terms of cobb angle, coronal and sagittal balance and sagittal pelvic parameters. MCGR can cause hypokyphosis and proximal junctional kyphosis in a minimum 2-year follow-up period. The implant-related complications were less in the MCGR group. However, larger case groups and longer follow-up periods are required for the better understanding of the superiority of one method on other in terms of complications.

Correlation between multifidus muscle atrophy, spinopelvic parameters, and severity of deformity in patients with adult degenerative scoliosis: the parallelogram effect of LMA on the diagonal through the apical vertebra

BACKGROUND

There were several reports describing the biomechanics and microstructure of multifidus muscles in patients with lumbar disc herniation. However, correlations between lumbar multifidus muscle atrophy (LMA), spinopelvic parameters, and severity of adult degenerative scoliosis (ADS) have not been investigated. The study evaluated the impact of LMA and spinopelvic parameters on the severity of ADS.

METHODS

One hundred and thirty-two patients with ADS were retrospectively reviewed. Standing whole-spine X-ray was used to evaluate the coronal (coronal Cobb angle, CA; coronal vertical axis, CVA) and sagittal (sagittal vertical axis, SVA; thoracic kyphosis, TK; lumbar lordosis, LL; pelvic incidence, PI; pelvic tilt, PT; sacral slope, SS) parameters. LMA was evaluated on axial T2-weighted magnetic resonance imaging (MRI) at intervertebral levels above and below the vertebra at the apex of the scoliotic curve. Clinical symptoms were evaluated by the Oswestry Disability Index (ODI) and the Japanese Orthopaedic Association (JOA) score. Multiple linear regression was used to assess correlations between LMA, spinopelvic parameters, and severity of scoliosis.

RESULTS

LL and PT were negatively correlated with CA (P < 0.001); LL was positively correlated with SVA (P < 0.001). PI was positively correlated with CA (P < 0.001) and CVA (P < 0.001). PT (P < 0.001) and SS (P < 0.001) were negatively correlated with CVA. SS was negatively correlated with SVA (P < 0.001). Concave LMA at the upper or lower intervertebral level of the apical vertebra was positively correlated with CA (P ≤ 0.001); convex LMA at the upper or lower intervertebral level was negatively correlated with CA (P < 0.001). Convex LMA at the upper intervertebral level and concave LMA at the lower intervertebral level of the apical vertebra were negatively correlated with the SVA (P ≤ 0.001). At the upper intervertebral level, LMA on the concave side was positively correlated with CVA (P = 0.028); LMA on the convex side was negatively correlated with CVA (P = 0.012). PI was positively correlated with ODI (P < 0.001); PT (P < 0.001) and SS (P < 0.001) were negatively correlated with ODI. At the lower intervertebral level, LMA on the concave side was positively correlated with ODI (P = 0.038); LMA on the convex side was negatively correlated with ODI (P = 0.011). PI was positively correlated with JOA (P < 0.001); PT (P < 0.001) and SS (P < 0.001) were negatively correlated with JOA.

CONCLUSIONS

Spinopelvic parameters are correlated with the severity of ADS. Asymmetric LMA at both upper and lower intervertebral levels of the apical vertebra is positively correlated with CA. LMA on the diagonal through the apical vertebra is very important to maintain sagittal imbalance via parallelogram effect. LMA at lower intervertebral levels of the apical vertebra may have a predictive effect on ODI. JOA score seems to be more correlated with spinopelvic parameters than LMA.

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

PURPOSE

To clarify the relationship between sarcopenia and spinopelvic parameters.

METHODS

Among outpatients of spine surgery department, 126 patients (mean age 77.2 years. 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.

RESULTS

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) (115.7 mm vs. 58.7 mm, 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.

CONCLUSIONS

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.

Anterior lumbar interbody fusions combined with posterior column osteotomy in patients who had sagittal imbalance associated with degenerative lumbar flat-back deformity: a retrospective case series

Anterior lumbar interbody fusion (ALIF) combined with posterior column osteotomy (PCO) may be effective to achieve ideal lumbar curve correction in lumbar flat-back deformity (LFD). We aimed to investigate the radiographic and clinical outcomes of patients with primary degenerative LFD treated with multi-level ALIFs combined with PCOs. Seventy patients with primary degenerative LFD who underwent corrective surgery were divided into three groups according to the 1-month postoperative pelvic incidence/lumbar lordosis (PI-LL) angles (≤ - 10°, from - 9° to 9°, and ≥ 10°). The spinopelvic parameters, including thoracic kyphosis, LL, pelvic tilt, T1 pelvic angle, and sagittal vertical axis, were analyzed at the preoperative, postoperative follow-up periods. The clinical outcomes, including the Oswestry disability index (ODI), visual analog scale (VAS), and Scoliosis Research Society (SRS)-22r, were also evaluated. Further, the paraspinal muscles were qualitatively and quantitatively examined, preoperatively. All spinopelvic parameters were corrected as close to the normal values at the 1-month postoperative period. The spinopelvic parameters in the PI-LL ≤ - 10° group were better corrected and maintained than those in the other groups. The ODI, VAS, and SRS-22r scores improved at the final follow-up in all groups. The PI-LL ≤ - 10° group showed better clinical outcomes than the other groups. In the paraspinal muscle examination, the mean lumbar muscularity value and fatty degeneration ratio were 236.7% and 20.7%, respectively. Multi-level ALIFs with PCOs in patients with LFD are effective in restoring sagittal balance and improving clinical symptoms. In addition, the postoperative LL angles should be larger than PI + 10° to achieve good overall outcomes in patients with severe degenerative back muscle.

Prevention of Adjacent Segmental Disease after Fusion in Degenerative Spinal Disorder: Correlation between Segmental Lumbar Lordosis Ratio and Pelvic Incidence-Lumbar Lordosis Mismatch for a Minimum 5-Year Follow-up

Study Design

Retrospective study.

Purpose

Associations among risk factors related to adjacent segmental disease (ASD) remain unclear. We evaluated the risk factors and segmental lordosis ratio to prevent ASD developing after lumbar spinal fusion.

Overview of Literature

Risk factors related to ASD development are age, sex, obesity, pre-existing degeneration, number of fusion segments, and decreased postoperative lumbar lordosis (LL). However, the associations among these factors are still unclear and should be clearly identified.

Methods

We retrospectively reviewed data on 274 patients who underwent lumbar spinal fusion of three segments or below for lumbar degenerative disease from January 2010 to December 2012, with over 5 years of follow-up. Patients with preoperative sagittal vertical axis (SVA) >5 cm were excluded due to sagittal imbalance. A total of 37 patients with ASD and 40 control patients (CTRL) were randomly selected in a similar distribution of matching variables: age, sex, and preoperative degenerative changes. Sex, age, number of fusion segments, radiologic measurements, L4–5–S1/L1–S1 LL ratio, and spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and SVA) were analyzed. Logistic regression was used to analyze the correlation between PI–LL mismatch and L4–5–S1 segmental lordosis rate.

Results

No significant difference was found between ASDs and CTRL groups regarding age, sex, number of fusion segments, fusion method, and preoperative and postoperative spinopelvic parameters (PI, SS, PT, and LL). However, regarding the L4–5–S1/L1–S1 lordosis ratio, 50% (p=0.045), 60% (p=0.031), 70% (p=0.042), 80% (p=0.023), and 90% (p=0.023) were statistically significant; <20% (p=0.478), 30% (p=0.223), and 40% (p=0.089) were not statistically significant. In the postoperative PI–LL <10 group, ASD occurred less frequently than in the PI–LL >10 group, and the difference was statistically significant (p=0.048).

Conclusions

Patients with a postoperative L4–5–S1/L1–S1 lordosis ratio >50% had less occurrence of ASD. Correcting LL according to PI and physiologic segmental lordosis ratio is important in preventing ASD.

The association between sacroiliac joint-related pain following lumbar spine surgery and spinopelvic parameters: a prospective multicenter study

PURPOSE

To prospectively calculate the incidence of postoperative sacroiliac joint-related pain (SIJP) and investigate the association between spinopelvic parameters and postoperative SIJP after lumbar spine surgery.

METHODS

We prospectively enrolled consecutive patients who underwent lumbar spine surgery. We defined postoperative SIJP as unilateral buttock pain according to fulfillment of the following criteria within 3 months of the surgery: a sacroiliac joint (SIJ) score higher than 4/9 postoperatively; positive response to analgesic periarticular SIJ injection with fluoroscopy; no other complications related to the surgery. The patients were divided into the SIJP group and non-SIJP group. We compared the background information and analyzed the differences in spinopelvic parameters in both groups. Additionally, receiver-operating characteristic curve analyses were performed to evaluate the cutoff values of spinopelvic parameters.

RESULTS

Of the 281 patients enrolled, 265 were included and eight developed postoperative SIJP (3.0%). There were no significant differences in the background information between groups. Preoperative and postoperative radiological evaluations revealed that the pelvic incidence (PI) in the SIJP group was significantly higher than that in the non-SIJP group, and there were no significant differences in lumbar lordosis (LL), pelvic tilt, sacral slope, and PI minus LL. For preoperative PI, the area under the curve, cutoff value, sensitivity, and specificity were 0.73739, 59, 62.5%, and 81.9%, respectively.

CONCLUSIONS

The incidence of postoperative SIJP after lumbar spine surgery was 3.0%. Higher PI values were associated with a higher risk of postoperative SIJP. These slides can be retrieved under Electronic Supplementary Material.

Back pain and sagittal spine alignment in obese patients eligible for bariatric surgery

OBJECTIVE

The objective of this research was to evaluate the prevalence of cervical and lumbar pain in obese patients eligible for bariatric surgery and to investigate possible changes in sagittal spine alignment in these patients.

METHODS

The following parameters were compared in 30 obese patients and a control group of 25 non-obese volunteers: body mass index, prevalence of cervical and lumbar pain assessed by visual analog scale (VAS), Neck Disability Index [NDI] and Oswestry Disability Index [ODI], as well as radiographic parameters of the spine and pelvis measured with Surgimap software.

RESULTS

The cervical and lumbar VAS and the NDI and ODI were significantly worse in obese patients. Compared with the control group, the cervical sagittal vertical axis (cSVA) of the obese group had higher variance (p value = 0.0025) and the cervical lordosis was diminished (p value = 0.0023). Thoracic kyphosis, lumbar lordosis, and the pelvic parameters were not significantly different between the groups.

CONCLUSIONS

Obese patients demonstrated lower functional performance compared with their non-obese counterparts, while cervical lordosis was diminished and the cSVA was increased in obese patients. These slides can be retrieved under Electronic Supplementary Material.

Sagittal Spinopelvic Parameters in Children With Achondroplasia

STUDY DESIGN

Retrospective cross-sectional, longitudinal radiographic analysis.

OBJECTIVE

To report the natural history of spinopelvic parameters in achondroplasia.

SUMMARY OF BACKGROUND DATA

Sagittal spinal deformity is common in children with achondroplasia. However, few data exist on their normative spinal parameters.

METHODS

Lateral standing spine radiographs of children with achondroplasia were reviewed. Measurements included thoracic kyphosis, lumbar lordosis (LL), thoracolumbar kyphosis (TLK), pelvic incidence (PI), T1 pelvic angle (TPA), and sagittal balance (SVA). Comparison between age groups and longitudinal analysis of children with minimum five-year radiographic evaluation was performed; evolution of radiographic measurements was assessed. Children who underwent surgical correction of TLK were studied separately to describe changes of sagittal spinal parameters associated with TLK surgical correction.

RESULTS

In cross-sectional analysis, 745 radiographs (282 children) were measured. During the first three years, TLK decreased and LL and sacral slope increased significantly. After age 3 years, TLK decreased gradually until age 10. Afterwards, TLK decrease became non-significant. PI increased gradually after age 10. In the longitudinal group, 81 children were followed an average of 8.7 (5-19) years between age 4.4 and 13.1 years. TLK decreased; LL and PI increased significantly. TPA and SVA remained within the normal range although changes with growth were statistically significant. In the surgical group, 19 children underwent surgical TLK correction. Apart from TLK correction, no sagittal parameters changed significantly after surgery. These 19 children had higher TLK and lower LL compared with a nonsurgical group at similar average age.

CONCLUSION

In children with achondroplasia, TLK improvement occurs primarily before age 3 years; hyperlordosis at the lumbosacral level is the compensatory mechanism. Significant changes in the sagittal spinal parameters occur early in life, suggesting the importance of attention to sagittal malalignment to prevent any possible clinical sequelae of severe hyperlordosis.

LEVEL OF EVIDENCE

Level III, prognostic study.

S1 Pedicle Subtraction Osteotomy in Sagittal Balance Correction. A Feasibility Study on Human Cadaveric Specimens

BACKGROUND

A cadaveric feasibility study was carried out. Osteotomies to correct fixed sagittal imbalance are usually performed at L₃/ L₄.

OBJECTIVE

To investigate the feasibility of S₁ pedicle subtraction osteotomy to correct spinal deformity and spinopelvic parameters, achieving better results with more limited exposure. The data obtained will allow a fixation construct specific for this osteotomy to be designed.

METHODS

S₁ pedicle subtraction osteotomy was performed on 12 cadaveric specimens. Baseline and postprocedural computed tomography and biomechanical studies were performed. Data were analyzed with a fixation system SolidWorks model, and the redesigned fixation construct was described and analyzed with an ANSYS model.

RESULTS

S₁ pedicle subtraction osteotomy is technically feasible. The fixation can be achieved with L₄, L₅, and iliac screws connected with bars. The system can be reinforced with a polyetheretherketone cage placed anteriorly in the S₁ body osteotomy site, a cross-connecting bar, a double iliac screw, or an anterior interbody cage placed at the L₅-S₁ disc. The fixation strength is improved by angulating the iliac rod channel 10°, adding a semi-sphere to the locking screw contact surface and 2 fins to its saddle. The redesigned construct showed suitable stress and deformation levels, achieving the expected biomechanical requirements.

DISCUSSION

Compared with surgery on higher levels, S₁ pedicle subtraction osteotomy allows greater correction with shorter fixation, because the osteotomy is performed at a more caudal level, modifying the spinopelvic parameters.

CONCLUSIONS

S₁ pedicle subtraction osteotomy is technically feasible. Finite element analysis results indicate that it has appropriate biomechanical properties.

The preoperative predictors for subsequent degeneration in L5-S1 disc after long fusion arthrodesis terminating at L5 in patients with adult scoliosis: focus on spinopelvic parameters

BACKGROUND

The subsequent L5-S1 disc degeneration associated with long fusion arthrodesis terminating at L5 in patients with adult scoliosis has been a common concern. However, few studies paid attention to its preoperative predictors, especially in spinopelvic parameters. The purpose of the present study was to clarify the preoperative predictors of subsequent L5-S1 disc degeneration after long fusion arthrodesis terminating at L5 in patients with adult scoliosis on spinopelvic parameters.

METHODS

In this retrospective study, we enrolled 67 patients with adult scoliosis, and the patients were divided into disc degeneration group (DD) and no disc degeneration group (NDD), based on the presence or absence of subsequent L5-S1 disc degeneration. The status of L5-S1 disc was evaluated by a modified version of radiographic classification. Characteristics and spinopelvic parameters of preoperative patients were collected as potential predictors for subsequent lumbosacral disc degeneration after long fusion arthrodesis terminating at L5 in patients with adult scoliosis. Multivariate logistic regression analysis and the receiver operating characteristic curve were used to identify the preoperative predictors, with an adjusted odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

Thirty-six patients (53.73%) with subsequent L5-S1 disc degeneration were divided into group DD (preoperative score 0.81 ± 0.57, last follow-up score 1.83 ± 0.60, P <  0.001), and the other 31 patients were divided into group NDD (preoperative and last follow-up score 0.87 ± 0.49). There was no statistical difference in preoperative score (P = 0.583) of lumbosacral disc between two groups; however, significant statistical difference showed in last follow-up score (P <  0.001). Multivariate logistic regression identified three preoperative predictors: pelvic incidence (PI) (P = 0.018), sagittal vertical axis (SVA) (P = 0.024), and sacrum-femoral distance (SFD) (P = 0.023). PI < 48.5° (OR = 0.911, 95% CI = 0.843-0.984), SVA > 4.43 cm (OR = 1.308, 95% CI = 1.036-1.649), and SFD > 5.65 cm (OR = 1.337, 95% CI = 1.041-1.718) showed satisfied accuracy for predicting subsequent L5-S1 disc degeneration.

CONCLUSION

The prevalence of the subsequent L5-S1 disc degeneration after long fusion arthrodesis terminating at L5 in patients with adult scoliosis was 57.3% (36 of 67 patients). PI < 48.5°, SVA > 4.43 cm, and SFD > 5.65 cm were preoperative predictors for the subsequent L5-S1 disc degeneration. More attention should be paid to prevent the L5-S1 disc from degeneration when these preoperative predictors exist, especially with two or more.

Evaluation of functional and structural leg length discrepancy in patients with adolescent idiopathic scoliosis using the EOS imaging system: a prospective comparative study

Background

To our knowledge, no studies have reported the exact structural leg length discrepancies (LLDs) in patients with adolescent idiopathic scoliosis (AIS). Therefore, this study aimed to evaluate the differences between functional and structural LLDs and to examine the correlations between LLDs and spinopelvic parameters in patients with AIS using an EOS imaging system, which permits the three-dimensional reconstruction of spinal and lower-limb bony structures.

Methods

Eighty-two consecutive patients with AIS underwent whole-body EOS radiography in a standing position between August 2014 and March 2016. Functional LLD, lumbar Cobb angle, thoracic curve Cobb angle, coronal balance, and pelvic obliquity were measured using two-dimensional EOS radiography. Structural LLDs were measured using three-dimensional EOS-reconstructed images. The comparison between LLDs was assessed using paired t test. Pearson's correlation coefficient (r) was used to determine potential correlations between the LLDs and spinopelvic alignment parameters.

Results

Functional LLDs were significantly larger than structural LLDs (5.6 ± 5.0 vs. 0.2 ± 3.6 mm, respectively; p < 0.001). Both functional and structural LLDs were significantly correlated with pelvic obliquity (r = 0.69 and r = 0.51, respectively; p < 0.001 for both). Functional LLD, but not structural LLD, was correlated with lumbar Cobb angle (r = 0.44, p < 0.001; r = 0.17, p = 0.12, respectively). In addition, functional and structural LLDs were not correlated with thoracic Cobb angle (r = 0.09 and r = - 0.05, respectively; p ≥ 0.68 for both).

Conclusions

Although patients with AIS often have functional LLDs, structural LLDs tend to be smaller. The correlation between functional LLDs and the lumbar Cobb angle indicates that functional LLDs compensate for the lumbar curve. Thus, the difference between functional and structural LLDs indicates a compensatory mechanism involving extension and flexion of the lower limbs.

Acquired spondylolysis and spinopelvic sagittal alignment

Acquired spondylolysis represents an uncommon complication of spine surgery, of an unknown incidence and etiology. We studied patients presenting this rare entity, with the purpose to investigate the incidence, imaging findings, patients' clinical characteristics, as well as to provide an interpretation of the mechanisms that may lead to this phenomenon. The presented working hypothesis, regarding etiology, suggests that there is a relation between variations in spinopelvic sagittal alignment and acquired spondylolysis. Between January 2010 and January 2015, six patients presented spondylolysis after short-segment transforaminal lumbar interbody fusion, at a mean time of 43 months after surgery. The preoperative intactness and postoperative defect of pars interarticularis were documented with computed tomography scans in all patients. Standard radiographical spinopelvic parameters were measured before and after surgery. The optimum values of lumbar lordosis (LL) and pelvic incidence minus lumbar lordosis modifier (PI-LL mismatch) were calculated as well. The incidence of acquired spondylolysis was 0.95% among patients with short-segment lumbar fusion. Patients presented high-grade PI with a vertically orientated sacral endplate, while LL was found 9° greater and PI-LL mismatch 9° lower than the respective optimum values, indicating a non-harmonized alignment. In conclusion, acquired spondylolysis, though rare, may occur in patients with high-grade PI and sacral slope, and suboptimal spinopelvic sagittal alignment after lumbar spine surgery, thereby highlighting the importance of detailed preoperative planning in spine surgery, along with the study of sagittal balance.