Degenerative Scoliosis

Is young adult idiopathic scoliosis a distinct clinical entity from adolescent idiopathic scoliosis? a Systematic Review and Meta-analysis comparing pre-operative characteristics and operative outcomes

PURPOSE

This study aims to conduct a systematic review of the literature comparing pre-operative, intraoperative, and post-operative characteristics between adolescent idiopathic scoliosis (AIS) and young adult idiopathic scoliosis (YAdIS) patients.

METHODS

Following PRISMA guidelines, we conducted a search of the PubMed/Medline, EMBASE, and Cochrane Central databases to identify full-text articles in the English-language literature. Our inclusion criteria were studies that compared preoperative, intraoperative, and postoperative characteristics between AIS and YAdIS patients. We performed a meta-analysis reporting mean difference (MD) for continuous variables and Odds ratios (ORs) to assess differences in postoperative complications.

RESULTS

Seven studies consisting of 1562 patients were included in the meta-analysis. The AIS group exhibited less intraoperative bleeding and shorter surgical procedures, with a mean difference between groups of 122.3 ml (95% CI 46.2-198.4, p = 0.002) and 28.7 min (95% CI 6.5-50.8, p = 0.01), respectively. Although the preoperative Cobb angle did not differ between groups (p = 0.65), patients with AIS achieved superior postoperative deformity correction, with a mean difference of 7.3% between groups, MD - 7.3 (95% CI - 9.7, - 4.8, p < 0.00001), and lower postoperative Cobb angles of the major curve, MD 4.2 (95% CI 3.1, 5.3, p < 0.00001). YAdIS patients were fused, on average, 0.2 more vertebral levels than AIS patients, MD 0.2 (95% CI 0.01, 0.5, p = 0.04). AIS patients experienced a significantly shorter length of stay after the surgical procedure, with an MD of 0.8 days (95% CI 0.1, 1.6, p = 0.02). No significant difference was found between groups in terms of complications (p = 0.19).

CONCLUSIONS

YAdIS should be regarded as a distinct surgical entity, characterized by increased bleeding, longer surgical duration, greater deformity correction challenges, and the need for fusion of additional vertebral levels compared to AIS. Surgeons should be mindful of these differences and discuss them with patients and their families, especially in cases where the correction of the AIS deformity is delayed and there is a high risk of progression after skeletal maturity. Further research is needed to explore alternative surgical techniques and enhance outcomes for YAdIS patients.

Intraoperative fat embolism syndrome associated with implantation of titanium sacroiliac joint fusion implants: a report of two cases

Background

For patients undergoing long-construct fusion surgeries, simultaneous sacroiliac joint (SIJ) fusion is a growing trend in spine surgery. Some options for posterior SIJ fusion include 3D-printed triangular titanium implants or self-harvesting SIJ screws. Both implants require fixation within the sacrum and ileum. Fat embolism syndrome is a rare but known complication of lumbar pedicle instrumentation but has never been reported in association with SIJ fusion, regardless of implant type. We report the first two known cases of fat embolism associated with placement of SIJ fusion devices during long construct posterior spine fusion.

Case Description

Case 1-a 50-year-old female with multiple previous spine surgeries complicated by osteomyelitis/diskitis that was successfully eradicated, underwent T10-pelvis posterior spinal fusion (PSF), L4 pedicle-subtracting-osteotomy, and bilateral SIJ fusion. During implantation of each SIJ fusion device, the patient's hemodynamic status deteriorated necessitating vasopressor support, intravenous fluid bolus, and hyperventilation, but quickly resolved. The case was completed without further issue, and she had an uneventful post-operative course. Case 2-a 71-year-old female with a past medical history of ankylosing spondylitis, previous L2-L5 PSF, rheumatoid arthritis on chronic steroids, underwent a T9-pelvis PSF, bilateral SIJ fusion, L4 pedicle subtraction osteotomy, T10-L1 Smith Peterson osteotomies. After implantation of the second SIJ fusion device, she became hypotensive and tachycardic, pulses were absent, and cardiopulmonary resuscitation was initiated. Pulses returned quickly, the index surgery was terminated, and she was transferred to the intensive care unit (ICU). In the ICU she was quickly weaned off the ventilator on post-operative day 1. On post-operative day 4, the patient returned to the operating room for completion of the surgery and had an extended, but uneventful, recovery afterwards.

Conclusions

We report on the first two known cases of fat embolism syndrome occurring immediately after implantation of SIJ fusion devices. Spine surgeons should be aware of this rare, but potentially fatal, complication. Collaboration with the anesthesia team and optimization of the patient's hemodynamic status prior to implantation may help prevent catastrophic complications.

Identification of key genes and regulatory mechanisms in adult degenerative scoliosis

BACKGROUND

Adult degenerative scoliosis (ADS) is a spinal disorder, but its pathogenesis remain unclear. Therefore, in this study, we utilized data from the GEO database and explored the key genes and regulatory mechanisms involved in ADS.

METHODS

We performed bioinformatics analysis on the GSE209825 dataset of GEO database. Weighted gene co-expression network analysis (WGCNA) was used to identify ADS-related gene modules, and we performed gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. We constructed a protein-protein interaction (PPI) network using the STRING database. We validated the specificity of hub genes in ADS using the GSE34095 dataset and plotted ROC curves for the identification of different degenerative spinal diseases based on the hub genes expression RESULTS: We identified 113 differentially expressed lncRNAs. WGCNA identified the MEblack module had the strongest correlation to ADS. GO and KEGG analyses of target genes in lncRNAs revealed their involvement in immune responses, inflammation, cellular processes, and metabolic pathways. Through PPI and ROC analysis, 10 hub genes linked to ADS diseases with certain specificity were found: ELANE, LTF, DEFA1B, SLC2A4, DEFA1, FAXDC2, LCN2, CTSB, FDFT1, and AURKA.

CONCLUSIONS

We identified 10 potential hub genes associated with ADS and constructed a transcription factors (TFs)-lncRNAs-hub genes regulatory network. These findings provide a new direction and research basis for the targeted treatment and mechanism research of ADS.

Associations between Degenerative Lumbar Scoliosis Structures and Pain Distribution in Adults with Chronic Low Back Pain

BACKGROUND

This study aimed to investigate the location and distribution of pain in adults with chronic low back pain (LBP) with degenerative lumbar scoliosis (DLS) according to coronal deformities.

METHODS

We enrolled 100 adults with chronic LBP and DLS, dividing them into two groups, a right-convex DLS group (n = 50) and a left-convex DLS group (n = 50). Dominant pain location was analyzed by dividing it into three parts-left side, right side, and center-and pain areas were identified using the pain drawing method; then, a heat map was created for each group. An association between pain location and convex side was analyzed as the primary outcome. Additionally, we assessed pain characteristics and radiological parameters, such as the curve structure and degree of degeneration. We used the Mann-Whitney U test or the chi-squared test to compare the clinical characteristics of the two groups, and generalized linear models were utilized to determine which variables were associated with pain severity or pain area.

RESULTS

The results indicated that there was no significant difference between the two groups in terms of the association between the curve structure, pain severity and location. In multivariate analysis, although we did not find any variables associated with pain severity, we observed that age and a left-convex DLS were negatively correlated with pain area among all participants. The heat map demonstrated that individuals with chronic LBP frequently experienced pain in the central lumbar region, regardless of the coronal curve structure.

CONCLUSIONS

Our findings suggest that degenerative coronal lumbar deformities may not have a specific pain pattern associated with a curved structure.

Overloaded axial stress activates the Wnt/β-Catenin pathway in nucleus pulposus cells of adult degenerative scoliosis combined with intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IVDD) is the initiating factor of adult degenerative scoliosis (ADS), and ADS further accelerates IVDD, creating a vicious cycle. Nevertheless, the role of the Wnt/β-Catenin pathway in ADS combined with IVDD (ADS-IVDD) remains a mystery. Accordingly, this study was proposed to investigate the effect of axial stress on the Wnt/β-Catenin pathway in nucleus pulposus cells (NPCs) isolated from DS-IVDD patients.

METHODS

Normal NPCs (N-NPC) were purchased and the NPCs of young (25-30 years; Y-NPC) and old (65-70 years; O-NPC) from ADS-IVDD patients were primary cultured. After treatment of NPC with overloaded axial pressure, CCK-8 and Annexin V-FITC kits were applied for detecting proliferation and apoptosis of N-NPC, Y-NPC and O-NPC, and western blotting was performed to assess the expression of Wnt 3a, β-Catenin, NPC markers and apoptosis markers (Bax, Bcl2 and Caspase 3).

RESULTS

N-NPC, Y-NPC and O-NPC were mainly oval, polygonal and spindle-shaped with pseudopods, and the cell morphology tended to be flattened with age. N-NPC, Y-NPC and O-NPC were capable of synthesizing proteoglycans and expressing the NPC markers (Collagen II and Aggrecan). Notably, the expression of Wnt 3a, β-Catenin, Collagen II and Aggrecan was reduced in N-NPC, Y-NPC and O-NPC in that order. After overload axial stress treatment, cell viability of N-NPC and Y-NPC was significantly reduced, and the percentage of apoptosis and expression of Wnt 3a and β-Catenin were significantly increased.

CONCLUSIONS

Overloaded axial pressure activates the Wnt/β-Catenin pathway to suppress proliferation and facilitate apoptosis of NPC in ADS-IVDD patients.

Barriers and facilitators to bracing in adults with painful degenerative scoliosis: a single-centred mixed-method feasibility study

BACKGROUND

Conservative treatments including bracing and exercise therapy are prescribed on the first-line in adults with degenerative scoliosis. However, adherence to conservative treatments is low. We aimed to assess barriers and facilitators to bracing in adults with painful degenerative scoliosis.

METHODS

We conducted a single-centred mixed-method pilot and feasibility study. All patients scheduled for a multidisciplinary custom-made bracing consultation, from July 2019 to January 2020, in a French tertiary care centre, were screened. Patients were eligible if they had painful adult degenerative scoliosis and a prescription for a rigid custom-made lumbar-sacral orthosis. The primary outcome was barriers and facilitators to bracing assessed by a qualitative approach using semi-structured interviews. Secondary outcomes were back pain, spine-specific activity limitations, symptoms of depression and satisfaction with bracing post-intervention assessed by a quantitative approach.

RESULTS

Overall, 56 patients were screened and 14 (25%) were included. Mean age was 68.2 (12.3) years. Mean follow-up was 9.8 (2.0) months. Barriers to bracing were increased limitations in some activities, discomfort in hot weather and burden of aesthetic appearance. Facilitators to bracing were reduced pain, improved activities of daily living, suitable weight and improved spinal alignment. Participants self-implemented solutions to enhance adherence. The mean reduction from baseline in pain intensity was 1.7 (2.3) of 10 points, and 6 of 13 patients (46%) had pain intensity < 4 of 10 points.

CONCLUSION

Bracing is a feasible intervention for people with painful adult degenerative scoliosis. Patients self-implemented their own solutions to enhance adherence.

Relationship between degenerative scoliosis and lower extremity mechanical parameters based on EOS imaging system

OBJECTIVE

This study aimed to assess the correlation between coronal imbalance and lower-limb physiological parameters in degenerative scoliosis using the biplanar whole body imaging system (EOS).

MATERIALS AND METHODS

A total of 101 successive EOS images were selected between January 2018 and December 2021. Of the selected images, 63 patients were in the degenerative scoliosis group (DSG) and 38 patients were in the control group (CG). Two independent observers performed measurements of the parameters and compared the two groups.

RESULTS

Among parameters examined, significant inter-group differences were found for coronal pelvic tilt angle (CPT), bilateral femoral length difference (ΔFL), and bilateral total lower limb length (ΔTL) difference. Additionally, the knee and ankle joints had more severe degeneration on the main curved side in patients with degenerative scoliosis. In the left curved group, 18 (42.86%) and 24 (57.1%) patients had more severe degeneration in the left knee and left ankle, respectively. In the right lateral bending group, 13 (61.9%) and 14 (66.7%) patients had more severe degeneration in the right knee and right ankle, respectively. Statistical differences were found in the degree of degeneration in both knee and ankle joints bilaterally.

CONCLUSION

This study showed that biomechanical parameters of the lower limbs are affected in cases of degenerative scoliosis with altered coronal balance. The lower limb on the main curve side became shorter compared to its counterpart, and joint degeneration of the knee and ankle joints became more severe.

Surgical outcome of minimal invasive oblique lateral interbody fusion with percutaneous pedicle screw fixation in the treatment of adult degenerative scoliosis

Oblique lateral interbody fusion is performed for lumbar spinal restoration and stabilization, without extensive paraspinal muscle damage or massive bleeding. This study aimed to confirm the radiological and clinical outcomes of minimally invasive oblique lateral interbody fusion (OLIF) with percutaneous pedicle screw fixation (PPSF) as treatment for adult degenerative lumbar scoliosis. Medical records of 40 patients with degenerative lumbar spinal deformities who underwent selective OLIF and PPSF at our hospital between April 2018 and February 2021 were retrospectively reviewed. The study population comprised 7 male and 33 female patients aged 55-79 years. Standing radiography was performed, and the coronal cobb angle, distance between the C7 plumb line and central sacral vertical line, sagittal vertical axis, pelvic tilt, lumbar lordosis (LL), pelvic incidence (PI), and difference between PI and LL (PI-LL) were measured. Coronal scoliosis was defined as a lumbar coronal plane curve of > 15°. All patients achieved statistically significant improvements in coronal and sagittal alignment. The coronal cobb angle was corrected from 18.82° to 11.52°, and the central sacral vertical line was reduced from 18.30 mm to 15.47 mm. The sagittal vertical axis was significantly reduced from 45.95 mm to 32.72 mm. In contrast, the pelvic tilt and LL were minimally changed. For subgroup analyses, patients were divided into the convex and concave groups according to the direction of coronal curve correction. Vertebral body rotation was superior in the convex group than in the concave group. Furthermore, we checked for asymmetric facet degeneration at the upper instrumented vertebra (UIV) level at 1 year postoperatively. Of the 22 patients who underwent more than 3 level fusion surgery, 8 patients were confirmed the postoperative asymmetric facet degeneration in above UIV. Minor complications occurred in 16 patients, who recovered without any problems. Revision surgery was not performed in all cases. Minimally invasive OLIF with PPSF has a lower risk of complications and favorable surgical outcomes in patients with adult degenerative lumbar scoliosis. Access from the convex side is advantageous for the correction of the rotated vertebra. Extending the UIV level to the neutral vertebra can reduce the occurrence of postoperative asymmetric facet degeneration.

RNA-Seq Comprehensive Analysis Reveals the Long Noncoding RNA Expression Profile and Coexpressed mRNA in Adult Degenerative Scoliosis

Objective: Owing to the intensification of the aging process worldwide, the prevalence of adult degenerative scoliosis (ADS) is increasing at an alarming rate. However, genomic research related to the etiology of ADS is rarely reported worldwide. Since long noncoding RNAs (lncRNAs) play a pivotal role in the progression of human diseases, this study aimed to investigate ADS-associated messenger RNAs (mRNAs) and lncRNAs by RNA sequencing (RNA-seq), as well as performed comprehensive bioinformatics analysis based on the lncRNA–mRNA coexpression network and protein–protein interaction (PPI) network.

Methods: Initially, six whole blood (WB) samples were obtained from three ADS and three nondegenerative lumbar trauma patients who underwent surgical operation for RNA-seq exploration to construct differential mRNA and lncRNA expression profiles. Subsequently, quantitative RT-PCR (qRT-PCR) was performed to validate three randomly selected differentially expressed mRNAs and lncRNAs derived from the nucleus pulposus (NP) tissue of 14 other subjects (seven ADS patients and seven nondegenerative lumbar trauma patients), respectively.

Results: A total of 1,651 upregulated and 1,524 downregulated mRNAs and 147 upregulated and 83 downregulated lncRNAs were screened out from the RNA-Seq data, which constructed coexpression networks to investigate their regulatory interactions further. GO gene function prediction revealed that lncRNA-targeted genes might play a vital role in ADS via participation in multiple biological processes such as the AMPK signaling pathway, lysosomes, and ubiquitin-mediated proteolysis, as well as cellular metabolic processes. Moreover, the expression levels of three selected lncRNAs and mRNAs were validated by qRT-PCR, respectively, demonstrating that the relative expression levels were consistent with the RNA-seq data. Notably, the dysregulated RNAs, AKT1, UBA52, PTPN12, and CLEC16A, were significantly differentially expressed in ADS WB samples and might serve as potentially regulated genes for research in the future.

Conclusions: This study provides the first insight into the altered transcriptome profile of long-stranded noncoding RNAs associated with ADS, which paves the way for further exploration of the clinical biomarkers and molecular regulatory mechanisms for this poorly understood degenerative disease. However, the detailed biological mechanisms underlying these candidate lncRNAs in ADS necessitate further elucidation in future studies.

Scoliosis incidence and treatment methods

Scoliosis is defined as a three-dimensional deformity of the spine that is of particular interest to the lateral curvature of the spine. Various types of treatment approaches have been recommended for patients with scoliosis. The aim of this study was to provide an up-to-date review of scoliosis, focusing on issues such as its incidence and treatment methods. The ISI-Thomson Web Of Science International Virtual Library was accessed for this review. The search criteria selected were 'title', 'abstract' and 'keywords'. In the ISI Thomson Web of Science virtual library platforms, the keywords in the articles search were "scoliosis incidence" and "scoliosis treatment". Over the years, different therapeutic strategies have been addressed for patients with scoliosis, they differ depending on the type of scoliosis, the patient's age and the available therapeutic means. Keywords: Scoliosis, Incidence, Physical Treatment;

Spinal Radiology associated with Redundant Nerve Roots of cauda equina in lumbar spine stenosis

OBJECTIVES

Redundant Nerve Roots (RNR) is a common radiological observation of elongated tortuous appearance of cauda equina nerve roots in sagittal MRI. It is considered a poor prognostic factor, but the associated spinal morphometry remains unfamiliar.

METHODS

A retrospective cohort study was conducted at the Aga Khan University Hospital, Pakistan. Patients, aged 18 or above, undergoing decompressive spinal surgery due to degenerative Lumbar Spinal Canal Stenosis (LSCS) in 2015 were included. Patients were divided in groups as per presence of RNR and assessed for spinal morphometric parameters.

RESULTS

Fifty-two patients, aged 57.52 ± 12.08 years, were enrolled in the study. The patients in RNR group were older than those in non-RNR group (p = 0.023). RNR was significantly associated with sedimentation sign (15 vs 11; p = 0.011), as well as L2/L3 (12 vs 9; p = 0.043) and L3/L4 (18 vs 18; p = 0.034) stenosis. Ligamentum flavum hypertrophy at the most stenotic level was more common in the RNR group (20 vs 19; p = 0.006). The only quantitative parameter statistically associated with RNR was lower ligamentous interfacet distance (5.07 ± 1.95 vs 8.07 ± 4.26 mm; p = 0.010). All other parameters did not contribute to the development of RNR in LSCS patients. The multivariate model revealed significant contribution of age, male sex, ligamentous interfacet distance and disc bulge to develop RNR.

CONCLUSION

Certain spinal morphometric parameters contribute towards RNR formation, which represents higher degree of spinal stenosis. These parameters, along with RNR, should be regularly reported for preoperative consideration of LSCS management.

Association and Risk of Axial Spondyloarthritis of Scoliosis Patients: A Database Study

STUDY DESIGN

Retrospective longitudinal cohort study.

OBJECTIVE

To investigate the incidence and risk of axial spondyloarthritis (axSpA) in patients with scoliosis in Taiwan.

SUMMARY OF BACKGROUND DATA

Scoliosis and axSpA causes back pain which reduces quality of life in many patients. Both scoliosis and axSpA had attracted numerous research attention, but the association between the two was hardly known.

METHODS

In this retrospective study, the data of 25,566 patients were obtained from Taiwan's National Health Insurance Research Database. We identified patients diagnosed with scoliosis and included them in the study cohort. We included age- and sex-matched patients without scoliosis in the control cohort. The total follow-up period was 7 years. Cox proportional hazards models were used to analyze the retrieved data. Hazard ratios (HRs) and adjusted HRs were calculated.

RESULTS

The study and control cohorts included 4261 and 21,305 patients, respectively. The incidences of axSpA were 141 and 46 per 100,000 person-years in the study and control cohorts, respectively. The crude HRs and adjusted HRs for patients with scoliosis were 2.98 (95% confidence interval, 1.87-4.73; P < 0.001) and 2.78 (95% confidence interval, 1.74-4.43; P < 0.001), respectively. The prevalence of comorbidities such as chronic obstructive pulmonary disease, osteoporosis, depression, autoimmune diseases (rheumatoid arthritis and systemic lupus erythematosus), and thyroid disease was significantly higher in the study cohort.

CONCLUSION

Our findings indicate an association between scoliosis and axSpA. Additional studies should be performed to explain this phenomenon.Level of Evidence: 3.

Monitoring scoliosis and other spinal deformity surgeries

Surgery to correct a spinal deformity incurs a risk of injury to the spinal cord and roots. Injuries include postoperative paraplegia. Surgery for cervical myelopathy also incurs risk for postoperative motor deficits, as well as nerve injury most commonly at the C5 root. Risks can be mitigated by monitoring the nervous system during surgery. Ideally, monitoring detects an impending injury in time to intervene and correct the impairment before it becomes permanent. Monitoring includes several modalities of testing. Somatosensory evoked potentials measure axonal conduction in the spinal cord posterior columns. This can be checked almost continuously during surgery. Motor evoked potentials measure conduction along the lateral corticospinal tracts. Because motor pathway stimulation often produces a patient movement on the table, these often are tested periodically rather than continuously. Electromyography observes for spontaneous discharges accompanying injuries, and is useful to assess misplacement of pedicle screws. Literature demonstrates the usefulness of these techniques, their association with reducing motor adverse outcomes, and the relative value of the techniques. Neurophysiologic monitoring for scoliosis, kyphosis, and cervical myelopathy surgery are addressed, along with background information about those conditions.

Gender differences in degenerative lumbar scoliosis spine flexibilities

OBJECTIVES

The incidence of adolescent idiopathic scoliosis is higher in girls, but spine deformities are more severe in boys. We aimed to identify gender differences of mechanical factors involved in adult degenerative scoliosis (DS).

METHODS

20 male (60.35±6.77 years) and 19 female (58.89±9.15 years) specimens of cadaveric lumbar spines were divided into 3 groups comprised of a Cobb angle >10° (DS), a Cobb angle <10° but >3° (pre-degenerative scoliosis (PS)) and intervertebral disc angles <3° in which the Cobb angle could not be measured (non-degenerative scoliosis (NS)), respectively. Spine data were collected for flexion/extension (FE), lateral bending (LB), axial torsion (AT), range of motion (ROM), neutral zone (NZ) and the neutral zone ratio (NZR).

RESULTS

There was no significant difference regarding the severity of DS between male and female specimens. Only in males were ROM_AT (P=0.001), NZ_AT (P<0.001), NZ_FE (P=0.045), NZ_LB (P=0.002) as well as NZR_AT (P<0.001) and NZR_LB (P=0.001) values significantly lower in right compared to left scoliosis. With the exception of ROM_AT in DS specimens, ROM_AT, ROM_FE and ROM_LB values were significantly higher in females than those in males for the DS, PS and NS specimens. NZ_AT, NZ_FE and NZ_LB values were significantly higher in PS and NS female specimens. NZR_AT was significantly lower in female DS specimens (P=0.031) and significantly higher in female PS specimens (P=0.031) compared to that in male specimens.

CONCLUSIONS

In lumbar scoliosis specimens, the rigidness of spines was higher in males than in females and more pronounced in right than in left scoliosis, but only in males.

Spine-Pelvis-Hip Alignments in Degenerative Spinal Deformity Patients and Associated Procedure of One-Stage Long-Fusion with Multiple-Level PLIF or Apical-Vertebra Three Column Osteotomy-a Clinical and Radiographic Analysis Study

OBJECTIVE

To explore the spine-pelvis-hip alignments in degenerative spinal deformity (DSD) patients, and compare the outcomes in the procedure of long-fusion with posterior lumbar inter-body fusion (PLIF) or single-level three-column osteotomy (STO) at lower lumbar level (LLL, L3 -S1 ) and thoracolumbar levels (TLL, T10 -L2 ) for those patients.

METHODS

This is a retrospective study. Following institutional ethics approval, a total of 83 patients (Female, 67; Male, 16) with DSD underwent long-fusion with PLIF or STO surgery between March 2015 and December 2017 were reviewed. All of those patients were assigned into LLL and TLL groups. The average age at surgery was 65.2 years (SD, 8.1). Demographic (age, gender, BMI, and comorbidities), radiographs (both coronal and sagittal parameters) and health-related quality of life (HRQOL) assessments were documented. The radiographic parameters and HRQOL-related measurements at pre- and post-operation were compared with paired-samples t test, and those variables in the two groups were analyzed using an independent-sample t test. The relationships between pelvic incidence (PI) and other sagittal parameters were investigated with Pearson correlation analysis. The Pearson χ2 or Fisher's exact was carried out for comparison of gender, incidence of comorbidities and post-operative complications.

RESULTS

There were 53 and 30 patients in the LLL and TLL groups respectively. Those spino-pelvic radiographic parameters had significant improvements after surgeries (P < 0.001). The patients in the two group with different pre-operative thoracolumbar kyphosis (TLK, P = 0.003), PI (P = 0.02), and mismatch of PI minus lumbar lordosis (PI-LL, P = 0.01) had comparable post-operative radiographic parameters except PI (P = 0.04) and pelvic-femur angle (PFA, P = 0.02). Comparing the changes of those spine-pelvic-hip data during surgeries, the corrections of TLK in TLL group were significant larger (P = 0.004). Pearson correlation analysis showed that there were negative relationship between PI and TLK (r = -0.302, P = 0.005), positive relationship between PI and LL (r = 0.261, P = 0.016) at pre-operation. Those patients underwent the surgical procedure that long-segment instrumentation and fusion with STO would have higher incidence of complications involving longer operative timing (P = 0.018), more blood loss (P < 0.001), revision surgery (P = 0.008), and cerebrospinal fluid leakage (P = 0.001). All the HRQOL scores significantly improved at final follow-up (P < 0.001), with no difference of intra-group.

CONCLUSION

Patients suffered de-novo scoliosis or hyper-kyphosis with low PI would be vulnerable to significant thoracolumbar degeneration, and have more changes of spine-pelvis-hip data after long-fusion surgery, however, those with high PI would be closed to significant lumbar degeneration. Although spine-pelvis-hip alignments in DSD patients can be restored effectively after long-fusion with PLIF or STO, the incidence of complications in patients underwent STO was significant higher than that in patients performed multi-level PLIF.

Association Between Vertebral Rotatory Subluxation and the Apical Vertebra in Degenerative Lumbar Scoliosis

OBJECTIVE

To identify the apical vertebra is relate to the occurrence of vertebral rotatory subluxation (VRS) in degenerative lumbar scoliosis.

METHODS

In total, 86 patients with degenerative lumbar scoliosis included in this retrospective study were divided into 2 groups: with VRS and without VRS. Coronal and sagittal parameters were measured on whole-spine anteroposterior and lateral radiographs. The impact of VRS on the spine and pelvis parameters was statistically analyzed, and the correlation between the occurrence of VRS and the apical vertebra was analyzed by using logistic regression.

RESULTS

VRS was present in 49 patients with degenerative lumbar scoliosis and absent in 37 patients. Compared with the patients without VRS, the patients with VRS had a smaller lumbar lordosis and thoracic kyphosis (P < 0.05) and a larger apical vertebra translation, apical vertebra tilt angle, Cobb angle, and pelvic incidence-lumbar lordosis (P < 0.05). Logistic regression analysis showed that apical vertebra translation and apical vertebra tilt angle were risk factors for the occurrence of VRS. The receiver operating characteristic curve analysis showed that apical vertebra translation greater than 23.2 mm and apical vertebra tilt angle greater than 11.8° were related to a greater probability of VRS in patients with degenerative lumbar scoliosis.

CONCLUSIONS

VRS is an important characteristic to consider in degenerative lumbar scoliosis that can affect the coronal and sagittal alignment. The apical vertebra is correlated with the occurrence of VRS; an apical vertebra translation greater than 23.2 mm and apical vertebra tilt angle greater than 11.8° are highly correlate with the occurrence of VRS.

Risk factors for screw loosening in patients with adult degenerative scoliosis: the importance of paraspinal muscle degeneration

Background

Paraspinal muscle is an important component to maintain spinal stability. But the relationship between the degeneration of paraspinal muscle and postoperative screw loosening in patients with adult degenerative scoliosis has not been studied. The objective of this study was to investigate risk factors for screw loosening in patients with adult degenerative scoliosis, including paraspinal muscle degeneration.

Methods

We investigated 93 patients with adult degenerative scoliosis who underwent spinal interbody fusion and pedicle screw fixation surgery. The lateral curvature was located in the lumbar spine and the follow-up time was ≥ 2 years. The patients were divided into loosening and non-loosening groups. Screw loosening was defined as a 1-mm or wider circumferential radiolucent line around the pedicle screw. We checked the cross-sectional area of paraspinal muscles, spinopelvic parameters, bone mineral density, number of fusion segment, and other factors. The potential risk factors for screw loosening were investigated by using binary logistical regression analysis.

Results

Fifty-seven patients showed screw loosening, which is 63.4% of total. Compared with patients in the non-loosening group, the cross-sectional area of erector spinae and psoas major muscle at L5 level were significantly smaller in patients with screw loosening (P < 0.05). Among these factors, the number of fused segments and relative erector spinae total cross-sectional area were independent risk factors for screw loosening.

Conclusions

The degeneration of paraspinal muscle and the increase of fusion segment were independent factors for screw loosening in patients with adult degenerative scoliosis.

Frailty as a risk factor for postoperative complications in adult patients with degenerative scoliosis administered posterior single approach, long-segment corrective surgery: a retrospective cohort study

Background

With the population aging worldwide, adult degenerative scoliosis (ADS) is receiving increased attention. Frailty, instead of chronological age, is used for assessing the patient’s overall physical condition. In ADS patients undergoing a posterior approach, long-segment corrective surgery, the association of frailty with the postsurgical outcomes remains undefined.

Methods

ADS patients who underwent a posterior approach, long-segment fusion at the Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University (CMU), Beijing, China, in 2014–2017 were divided into the frailty and non-frailty groups according to the modified frailty index. Major postoperative complications were recorded, including cardiac complications, pneumonia, acute renal dysfunction, delirium, stroke, neurological deficit, deep wound infection, gastrointestinal adverse events, and deep vein thrombosis. Radiographic measurements and health-related quality of life (HRQOL) parameters were recorded preoperatively and at 2 postoperative years.

Results

A total of 161 patients were included: 47 (29.2%) and 114 (70.8%) in the frailty and non-frailty groups, respectively. Major postoperative complications were more frequent in the frailty group than the non-frailty group (29.8% vs. 10.5%, P = 0.002). Multivariable logistic regression analysis showed that frailty was independently associated with major complications (adjusted odds ratio [aOR] = 2.77, 95% confidence interval [CI] 1.12–6.89, P = 0.028). Radiographic and HRQOL parameters were improved at 2 years but with no significant between-group differences.

Conclusions

Frailty is a risk factor for postoperative complications in ADS after posterior single approach, long-segment corrective surgery. Frailty screening should be applied preoperatively in all patients to optimize the surgical conditions in ADS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04186-9.

Correlation of vertebral trabecular attenuation in Hounsfield units and the upper instrumented vertebra with proximal junctional failure after surgical treatment of degenerative lumbar disease

OBJECTIVE

The aim of this study was to investigate whether bone mineral density (BMD) measured in Hounsfield units (HUs) is correlated with proximal junctional failure (PJF).

METHODS

A retrospective study of 104 patients with adult degenerative lumbar disease was performed. All patients underwent posterior instrumented fusion of 4 or more segments and were followed up for at least 2 years. Patients were divided into two groups on the basis of whether they had mechanical complications of PJF. Age, sex ratio, BMI, follow-up time, upper instrumented vertebra (UIV), lower instrumented vertebra, and vertebral body osteotomy were recorded. The spinopelvic parameters were measured on early postoperative radiographs. The HU value of L1 trabecular attenuation was measured on axial and sagittal CT scans. Statistical analysis was performed to compare the difference of continuous and categorical variables. Receiver operating characteristic (ROC) curve analysis was used to obtain attenuation thresholds. A Kaplan-Meier curve and log-rank test were used to analyze the differences in PJF-free survival. Multivariate analysis via a Cox proportional hazards model was used to analyze the risk factors.

RESULTS

The HU value of L1 trabecular attenuation in the PJF group was lower than that in the control group (p < 0.001). The spinopelvic parameter L4-S1 lordosis was significantly different between the groups (p = 0.033). ROC curve analysis determined an optimal threshold of 89.25 HUs (sensitivity = 78.3%, specificity = 80.2%, area under the ROC curve = 0.799). PJF-free survival significantly decreased in patients with L1 attenuation ≤ 89.25 HUs (p < 0.001, log-rank test). When L1 trabecular attenuation was ≤ 89.25 HUs, PJF-free survival in patients with the UIV at L2 was the lowest, compared with patients with their UIV at the thoracolumbar junction or above (p = 0.028, log-rank test).

CONCLUSIONS

HUs could provide important information for surgeons to make a treatment plan to prevent PJF. L1 trabecular attenuation ≤ 89.25 HUs measured by spinal CT scanning could predict the incidence of PJF. Under this condition, the UIV at L2 significantly increases the incidence of PJF.

Outcome analysis of lumbar endoscopic unilateral laminotomy for bilateral decompression in patients with degenerative lumbar central canal stenosis

BACKGROUND CONTEXT

Lumbar endoscopic unilateral laminotomy for bilateral decompression (LE-ULBD) has been reported as an alternative treatment for degenerative lumbar central canal stenosis (DLCS).

PURPOSE

To investigate the outcomes of LE-ULBD for different types of DLCS, including simple DLCS, DLCS with degenerative spondylolisthesis (DSL), and DLCS with degenerative scoliosis (DSC).

STUDY DESIGN/SETTING

Prospective cohort study.

PATIENT SAMPLE

One-hundred sixteen patients with DLCS who underwent LE-ULBD at a spine center from April 2015 to June 2017 were enrolled in this study.

OUTCOME MEASURES

Operative time, postoperative duration of hospitalization, and clinical outcomes (Oswestry disability index [ODI], visual analog scale [VAS], and modified Macnab outcome scale), and adverse events.

METHODS

A comparative analysis was performed evaluating medical records, radiological studies, and patient reported outcomes including ODI score, VAS scores and modified Macnab outcome scales in patients who underwent LE-ULBD. Data were prospectively collected at preoperative, postoperative 3-, 6-, 12-, 24-month to assess clinical and radiological outcomes and complications.

RESULTS

The study analyzed 106 patients (45 men and 61 women, with a mean age of 69.5 years); 40 (37.8%) had simple DLCS, 41 (38.7%) had DLCS with DSL, and 25 (23.5%) had DLCS with DSC. The mean follow-up period was 33.3 months. The mean preoperative and postoperative follow-up ODI score and VAS scores for leg and back pain showed significant improvement in all time points. No significant difference was found among different pathologies in terms of VAS scores for back and leg pain, ODI scores and modified Macnab outcome scales at all follow-up periods.

CONCLUSIONS

LE-ULBD is a feasible treatment method for DLCS. It did not result in worse outcomes in cases with DLCS with DSL or DLCS with DSC as compared with cases with simple DLCS.

Unfulfilled Expectations After Surgery for Adult Lumbar Scoliosis Compared with Other Degenerative Conditions

BACKGROUND

Patients' expectations influence their decisions to undergo surgery for scoliosis, and fulfillment of expectations is an important patient-centered outcome.

QUESTIONS/PURPOSES

In a 2-year cohort study, we compared the proportion of expectations fulfilled based on the number of vertebrae involved in surgery between adult lumbar scoliosis patients and controls with other degenerative conditions.

METHODS

Patients pre-operatively completed a valid lumbar surgery expectations survey addressing expected improvements for symptoms, function, and psychosocial well-being (scores from 0 to 100; higher score indicates more expectations). Two years post-operatively, the patients completed another survey, this one recording how much improvement they actually experienced; fulfillment was defined as a proportion (i.e., received improvement/expected improvement). The range was 0 (none fulfilled) to > 1 (expectations surpassed). We further analyzed data according to the number of vertebrae involved in the surgery.

RESULTS

We included 42 scoliosis patients and 134 controls with similar mean ages (66 vs 64 years, respectively) and pre-operative expectations survey scores (72 vs 70, respectively). When we stratified by < 3 or ≥ 3 vertebrae, we found that the proportion of expectations fulfilled differed for scoliosis patients but not for controls. In multivariable analysis, lower proportion of expectations fulfilled was associated with greater pre-operative expectations, less improvement in pre- to post-operative disability, and the composite interaction of scoliosis and number of vertebrae.

CONCLUSIONS

Compared with controls, scoliosis patients who required surgery to a greater number of vertebrae were more likely to have unfulfilled expectations 2 years post-operatively. Our findings support the importance of addressing expectations pre-operatively with all patients, especially those with scoliosis who require surgery to ≥ 3 vertebrae.

Rehabilitation in adult spinal deformity

Adult spinal deformity causes significant health-related problems such as pain and disability in adults. Currently, there are several non-operative management strategies such as pain medications, physical modalities, exercises, bracing or interventional procedures. Specific exercises including strengthening of back and abdominal muscles, neuromuscular re-education for daily tasks, and active self-correction are vital to improve postural control and spinal stability. Bracing for a few hours a day can help reduce pain and provide spinal stability in adults. In case of severe disability and pain unresponsive to non-operative treatments, spinal fusion with instrumentation is an alternative. Postoperative rehabilitation can help to reduce pain and disability and improve return to activity or work. Protecting the spine early after surgery and timing of initiation of exercises with respect to osseointegration and bone remodeling phases are important principles of postoperative rehabilitation. In this review, rehabilitation in adult spinal deformity is discussed in the light of the literature.

Adult Degenerative Scoliosis

Populational aging increases the incidence of musculoskeletal degenerative processes, such as adult scoliosis (AS). Adult scoliosis is defined as a spinal deformity in the coronal plane with a Cobb angle > 10°. Adult scoliosis may be iatrogenic or result from a degenerative process (scoliosis de novo ) or a pre-existing scoliosis.

Adult scoliosis is a potentially limiting condition that affects a heterogeneous group of patients. Clinical treatment proved to be ineffective and surgery is often indicated. The present paper reviews AS pathophysiology, clinical presentation and diagnosis, in addition to surgical indications and the main techniques currently used.

Outcomes of Nonsurgical Treatments for Symptomatic Adult Degenerative Scoliosis: A Systematic Review

OBJECTIVE

To evaluate the effectiveness of nonsurgical treatments in symptomatic adult degenerative scoliosis (ADS).

DESIGN

A systematic literature review.

METHODS

PubMed, Web of Science, and The Cochrane Library were searched to identify research published since 1988. Randomized controlled trials (RCTs) and observational cohort studies were eligible if they featured symptomatic ADS patients aged ≥50 who received nonsurgical treatment. Minimum follow-up was six weeks, and outcomes of interest were pain, disability, quality of life, and Cobb angle. Evidence quality per intervention was rated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

Six studies were included. Of these, four focused specifically on injections, bracing, or yoga; two involved multiple treatments. One RCT provided evidence for greater effectiveness of transforaminal epidural steroid injection over anesthetic alone in reducing radiating pain and disability. Two single-group retrospective cohort studies lent support for bracing to slow curve progression. One retrospective single-group cohort study suggested an association between yoga and reduced curve progression. Evidence for injections to reduce ADS symptoms was rated as low quality; evidence for bracing and yoga was rated as very low quality. No specific evidence was identified regarding other treatments, including physical therapy and analgesics.

CONCLUSIONS

Literature describing the effectiveness of nonoperative treatments in symptomatic ADS is scarce. The quantity and quality of the evidence regarding injections, bracing, and yoga are insufficient to advise for or against the use of these methods to improve outcomes in symptomatic ADS. For these and other nonoperative treatment forms, further research is needed.

[Effectiveness of short fusion versus long fusion for degenerative scoliosis with a Cobb angle of 20-40° combined with spinal stenosis]

Objective

To compare the effectiveness of decompression and short fusion or long fusion for degenerative scoliosis (DS) with a Cobb angle of 20-40° combined with spinal stenosis.

Methods

The clinical data of 50 patients with DS who were treated with decompression combined with short fusion or long fusion between January 2015 and May 2017 were retrospectively analysed. Patients were divided into long fusion group (fixed segments>3, 23 cases) and short fusion group (fixed segments≤3, 27 cases). There was no significant difference in gender, age, disease duration, and preoperative visual analogue scale (VAS) score of leg pain, Oswestry disability index (ODI), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), pelvic incidence (PI), pelvic title (PT), and sacral slope (SS) between the two groups ( P>0.05); however, the VAS score of low back pain, Cobb angle, and sagittal vertical axis (SVA) in long fusion group were significantly higher than those in short fusion group ( P<0.05), and the lumbar lordosis (LL) was significantly lower than that in short fusion group ( t=2.427, P=0.019). The operation time, intraoperative blood loss, fluoroscopy times, hospital stay, and complications were recorded and compared. The VAS scores of low back pain and leg pain and ODI score were used to evaluate the clinical outcomes before operation and at last follow-up. X-ray films of the whole spine in standard standing position were taken before operation, at 6 months after operation, and at last follow-up, and the spino-pelvic parameters were measured.

Results

The operation time, intraoperative blood loss, and fluoroscopy times in the short fusion group were significantly less than those in the long fusion group ( P<0.05); there was no significant difference in hospital stay between the two groups ( t=0.933, P=0.355). The patients were followed up 12-46 months with an average of 22.3 months. At last follow-up, the VAS scores of low back pain and leg pain and ODI score significantly improved when compared with those before operation ( P<0.05). Except for the improvement of VAS score of low back pain ( t=8.332, P=0.000), the differences of the improvements of the other scores between the two groups were not significant ( P>0.05). The Cobb angle, SVA, TLK, and PT significantly decreased, while SS and LL significantly increased in the long fusion group ( P<0.05), while the Cobb angle and PT significantly decreased and SS significantly increased in the short fusion group at last follow-up ( P<0.05). There was no significant difference in spino-pelvic parameters between the two groups at 6 months after operation and at last follow-up ( P>0.05). The improvements of Cobb angle, SVA, LL, PT, and SS in the long fusion group were significantly higher than those in the short fusion group at last follow-up ( P<0.05). There was no perioperative death in both groups. The incidence of complications in the long fusion group was 34.8% (8/23), which was significantly higher than that in the short fusion group [11.1% (3/27)] ( χ ²=4.056, P=0.034).

Conclusion

The DS patients with the Cobb angle of 20-40°can achieve satisfactory clinical outcomes and improve the spino-pelvic parameters by choosing appropriate fixation levels. Short fusion has less surgical trauma and fewer complications, whereas long fusion has more advantages in enhancing spino-pelvic parameters and relieving low back pain.

Biomechanical properties in motion of lumbar spines with degenerative scoliosis

Degenerative lumbar scoliosis presumably alters spinal biomechanics, but a lack of quantitative reference measurements of these spines exists. We aimed to assess the biomechanical properties of spines with degenerative scoliosis, and to relate these to intervertebral disc degeneration (DD) and Cobb angle. Secondly, we compared these results to previous measurements of non-scoliotic spines. Ten cadaveric spines (Th12-L5, mean age 82 ± 11 years) with Cobb angle ≥10° and apex at L3 were acquired. Three loading cycles (-4 to 4 Nm) were applied in flexion/extension (FE), lateral bending (LB), and axial rotation (AR). The range of motion (ROM), neutral zone (NZ) stiffness, NZ ROM, elastic zone (EZ) stiffness and hysteresis were calculated for each motion segment in the loading direction. ROM was calculated in coupled directions, expressed as a percentage of rotation in the loaded direction. For Th12-L5, there was a ROM (degrees ± SD) of 14.9 ± 6.5 in FE, 14.9 ± 7.8 in LB, and 10.2 ± 5.5 in AR. The median (Nm/degree (Q1;Q3)) NZs was 0.24 (0.19;0.35) in FE, 0.25 (0.22;0.42) in LB, and 0.49 (0.33;0.99) in AR. Greater coupled motions related to higher Cobb angle, especially during AR on segments around the apex (FE: ρ = 0.539, p = 0.021 and LB: ρ = 0.821, p = 0.000). DD correlated to lower ROM and increased NZs on L2-L3 in FE (ρ = -0.721, p = 0.028 and ρ = 0.694, p = 0.038, respectively). Compared to non-scoliotic spines, smaller ROM in FE (p = 0.030) was found. This study describes the biomechanical properties of lumbar spines with degenerative scoliosis. Compared to non-scoliotic spines, they tended to be stiffer and exhibited smaller ROM in FE. DD only affected the ROM and NZs of the segments around the apex.

The biomechanical effect of single-level laminectomy and posterior instrumentation on spinal stability in degenerative lumbar scoliosis: a human cadaveric study

OBJECTIVEDegenerative lumbar scoliosis, or de novo degenerative lumbar scoliosis, can result in spinal canal stenosis, which is often accompanied by disabling symptoms. When surgically treated, a single-level laminectomy is performed and short-segment posterior instrumentation is placed to restore stability. However, the effects of laminectomy on spinal stability and the necessity of placing posterior instrumentation are unknown. Therefore, the aim of this study was to assess the stability of lumbar spines with degenerative scoliosis, characterized by the range of motion (ROM) and neutral zone (NZ) stiffness, after laminectomy and placement of posterior instrumentation.METHODSTen lumbar cadaveric spines (T12-L5) with a Cobb angle ≥ 10° and an apex on L3 were included. Three loading cycles were applied per direction, from -4 Nm to 4 Nm in flexion/extension (FE), lateral bending (LB), and axial rotation (AR). Biomechanical evaluation was performed on the native spines and after subsequent L3 laminectomy and the placement of posterior L2-4 titanium rods and pedicle screws. Nonparametric and parametric tests were used to analyze the effects of laminectomy and posterior instrumentation on NZ stiffness and ROM, respectively, both on an individual segment's motion and on the entire spine section. Spearman's rank correlation coefficient was used to study the correlation between disc degeneration and spinal stability.RESULTSThe laminectomy increased ROM by 9.5% in FE (p = 0.04) and 4.6% in LB (p = 0.01). For NZ stiffness, the laminectomy produced no significant effects. Posterior instrumentation resulted in a decrease in ROM in all loading directions (-22.2%, -24.4%, and -17.6% for FE, LB, and AR, respectively; all p < 0.05) and an increase in NZ stiffness (+44.7%, +51.7%, and +35.2% for FE, LB, and AR, respectively; all p < 0.05). The same changes were seen in the individual segments around the apex, while the adjacent, untreated segments were mostly unaffected. Intervertebral disc degeneration was found to be positively correlated to decreased ROM and increased NZ stiffness.CONCLUSIONSLaminectomy in lumbar spines with degenerative scoliosis did not result in severe spinal instability, whereas posterior instrumentation resulted in a rigid construct. Also, prior to surgery, the spines already had lower ROM and higher NZ stiffness in comparison to values shown in earlier studies on nonscoliotic spines of the same age. Hence, the authors question the clinical need for posterior instrumentation to avoid instability.

[Effectiveness of nano-hydroxyapatite/polyamide-66 Cage in interbody fusion for degenerative lumbar scoliosis]

Objective

To explore the effectiveness of nano-hydroxyapatite/polyamide-66 (n-HA/PA66) Cage in interbody fusion for degenerative lumbar scoliosis.

Methods

A retrospective analysis was designed and conducted for 43 patients, who underwent posterior decompression and n-HA/PA66 Cage interbody fusion with correction of deformity between January 2013 and June 2016. Eighteen cases were single-level fusion (single-level group) and 25 cases were double-level fusion (double-level group). There was no significant difference in gender, age, body mass index, direction of convex, degree of apical rotation, fusion level, the number of osteoporotic patients, pre-operative intervertebral height of fusion segments, coronal Cobb angle, visual analogue score (VAS), and modified Oswestry Disability Index (ODI) between 2 groups ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospital stay, and complications of the operation were recorded. Modified ODI, VAS score, and MacNab criteria were adopted to assess clinical outcomes. Radiographic indexes, including intervertebral height of fusion segments, coronal Cobb angle, disc insertion depth, and the bone graft fusion rate, were also evaluated.

Results

There was no significant difference in operation time, intraoperative blood loss, postoperative drainage, and hospital stay between 2 groups ( P>0.05). All patients were followed up 18-62 months (mean, 30.9 months). Wound complications, postoperative delirium, and Cage retropulsion occurred in 4 cases (2 cases in single-level group, 2 cases in double-level group), 1 case of single-level group, and 1 case of double-level group, respectively. The intervertebral height of fusion segments after operation significantly improved compared with preoperative ones in both groups ( P<0.05). At last follow-up, the intervertebral height in double-level group was superior to which in single-level group ( P<0.05). The coronal Cobb angles after operation significantly improved compared with preoperative ones ( P<0.05), and no significant difference was found between 2 groups at each time point ( P>0.05). The disc insertion depth showed no significant difference between different time points after operation in 2 groups ( P>0.05) and between 2 groups at each time point after operation ( P>0.05). Bony fusion was obtained in all patients at last follow-up. The VAS score and modified ODI after operation in both groups were superior to those before operation ( P<0.05). The VAS score in double-level group was higher than that in single-level group ( P<0.05) at last follow-up, and no significant difference was found in VAS score and modified ODI between 2 groups at other time points ( P>0.05). According to the MacNab criteria, the excellent and good rates at last follow-up were 94.4% and 84.0% in single-level group and double-level group, respectively.

Conclusion

The n-HA/PA66 Cage can effectively restore and maintain the disc height of fusion segment, normal sequence, and biomechanical stability of the spine, and gain favorable effectivenss for degenerative lumbar scoliosis. And double-level fusion is superior to single-level fusion in maintaining disc height of fusion segment.