Pelvic thickness, sex, ethnicity, and age affect pelvic incidence in healthy volunteers of Multi-Ethnic Alignment Normative Study (MEANS) database.

BACKGROUND: The purpose of this study was to investigate the affecting factors on pelvic incidence (PI) and to test the hypothesis that PI changes even after skeletal maturity probably due to hypermobility of the sacroiliac joint using a large international multi-center database. METHODS: A prospective and cross-sectional healthy adult volunteers, ages 18-80 years, across 5 countries were used. Radiographic measurements included standard whole body alignment parameters. Bivariate regression analyses between PI versus demographics and spino-pelvic anatomical parameters were performed. An effect of sex on pelvic anatomical parameters was also investigated. Multivariate logistic regression with a forward stepwise procedure was performed to identify the contributing factors to PI, and an appropriate model was obtained. RESULTS: PI showed a significant positive correlation with age in pooled data. Divided by sex, however, there was no correlation in men, but women showed a significant higher correlation coefficient. Pelvic thickness (PTh) had a significant negative correlation with age in pooled data. Divided by sex, no correlation was found in men, but there was a significant correlation in women with higher correlation coefficient. The stepwise multivariate analysis for the factors on PI identified four significant factors: age, sex, ethnicity, and PTh. CONCLUSIONS: PTh, sex, ethnicity, and age affected PI. There was a positive correlation between PI and age. The tendency was more significant in woman than in man. The results support the hypothesis that PI increases with aging, but the change seems to be small and needs to be verified in a longitudinal evaluation.

Correlation analysis of the PI-LL mismatch according to the pelvic incidence from a database of 468 asymptomatic volunteers.

PURPOSE: Previous studies on adults with degenerative scoliosis (ADS) have been fixed the threshold of PI-LL mismatch less than 10° for achieving good clinical outcomes. Recent studies discussed that PI-LL mismatch should consider individual pelvic incidence (PI) and should be set first in a normal population. The purpose of this study is to assess the variability of PI-LL mismatch according to PI in an asymptomatic population. METHODS: Full-body low dose stereoradiographic evaluation was done in a multi-ethnic cohort of 468 asymptomatic adult volunteers. Patients were clustered in three groups depending on individual PI values: PI < 45°, 45° < PI < 60° and PI > 60°. 3D measurements were performed using a commercially available 2D/3D modeling software to establish a correlation of PI with other spinopelvic parameters. ANOVA and Tukey's HSD for post-hoc analysis were used to determine the differences between the three groups. RESULTS: In our asymptomatic population, the mean value of PI-LL mismatch is - 5.4° ± 10.7°. Clusterization of the population reveals significant differences in the distribution of L1S1 lordosis, pelvic tilt and PI-LL with positive linear correlation according to PI values. As an interestingly result, PI-LL mismatch is equal to 0° when PI is around 64°. CONCLUSIONS: The present study demonstrated that PI-LL mismatch is negative in an asymptomatic population (- 5.4° ± 10.7°) and the value should be customized to each patient to be able to restore the appropriate lordosis in ADS. The PI-LL mismatch is given by the formula PI-LL = - 28.5 + 0.44 × PI.

ProDisc-C versus anterior cervical discectomy and fusion for the surgical treatment of symptomatic cervical disc disease: two-year outcomes of Asian prospective randomized controlled multicentre study.

PURPOSE: Our study aimed to evaluate non-inferiority of ProDisc-C to anterior cervical discectomy and fusion (ACDF) in terms of clinical outcomes and incidence of adjacent segment disease (ASD) at 24-months post-surgery in Asian patients with symptomatic cervical disc disease (SCDD). METHODS: This multicentre, prospective, randomized controlled trial was initiated after ethics committee approval at nine centres (China/Hong Kong/Korea/Singapore/Taiwan). Patients with single-level SCDD involving C3-C7-vertebral segments were randomized (2:1) into: group-A treated with ProDisc-C and group-B with ACDF. Assessments were conducted at baseline, 6-weeks, 3/6/12/18/24-months post-surgery and annually thereafter till 84-months. Primary endpoint was overall success at 24-months, defined as composite of: (1) ≥ 20% improvement in neck disability index (NDI); (2) maintained/improved neurologic parameters; (3) no implant removal/revision/re-operation at index level; and (4) no adverse/severe/life-threatening events. RESULTS: Of 120 patients (80ProDisc-C,40ACDF), 76 and 37 were treated as per protocol (PP). Overall success (PP) was 76.5% in group-A and 81.8% in group-B at 24-months (p = 0.12), indicating no clear non-inferiority of ProDisc-C to ACDF. Secondary outcomes improved for both groups with no significant inter-group differences. Occurrence of ASD was higher in group-B with no significant between-group differences. Range of motion (ROM) was sustained with ProDisc-C but lost with ACDF at 24-months. CONCLUSION: Cervical TDR with ProDisc-C is feasible, safe, and effective for treatment of SCDD in Asians. No clear non-inferiority was demonstrated between ProDisc-C and ACDF. However, patients treated with ProDisc-C demonstrated significant improvement in NDI, neurologic success, pain scores, and 36-item-short-form survey, along with ROM preservation at 24-months. Enrolment difficulties resulted in inability to achieve pre-planned sample size to prove non-inferiority. Future Asian-focused, large-scale studies are needed to establish unbiased efficacy of ProDisc-C to ACDF.

A novel hospital capacity versus clinical justification triage score (CCTS) for prioritization of spinal surgeries in the "new normal state" of the COVID-19 pandemic.

INTRODUCTION: During the Coronavirus disease 2019 outbreak, while healthcare systems and hospitals are diverting their resources to combat the pandemic, patients who require spinal surgeries continue to accumulate. The aim of this study is to describe a novel hospital capacity versus clinical justification triage score (CCTS) to prioritize patients who require surgery during the "new normal state" of the COVID-19 pandemic. METHODOLOGY: A consensus study using the Delphi technique was carried out among clinicians from the Orthopaedic Surgery, Neurosurgery, and Anaesthesia departments. Three rounds of consensus were carried out via survey and Webinar discussions. RESULTS: A 50-points score system consisting of 4 domains with 4 subdomains was formed. The CCTS were categorized into the hospital capacity, patient factors, disease severity, and surgery complexity domains. A score between 30 and 50 points indicated that the proposed operation should proceed without delay. A score of less than 20 indicates that the proposed operation should be postponed. A score between 20 and 29 indicates that the surgery falls within a grey area where further discussion should be undertaken to make a joint justification for approval of surgery. CONCLUSION: This study is a proof of concept for the novel CCTS scoring system to prioritize surgeries to meet the rapidly changing demands of the COVID-19 pandemic. It offers a simple and objective method to stratify patients who require surgery and allows these complex and difficult decisions to be unbiased and made transparently among surgeons and hospital administrators.

The odontoid-CSVL distance in a global population of asymptomatic volunteers: normative values and implications for spinal coronal alignment.

PURPOSE: In a population of asymptomatic volunteers across 5 countries, we sought to: (a) establish normative values of the Odontoid-Central Sacral Vertical Line (OD-CSVL) across patient factors, and (b) assess correlations of OD-CSVL with other radiographic parameters. METHODS: A prospective, cross-sectional study of asymptomatic adult volunteers, ages 18-80 years, were enrolled across 5 countries (France, Japan, Singapore, Tunisia, United States) forming the Multi-Ethnic Alignment Normative Study (MEANS) cohort. Included volunteers had no known spinal disorder(s), no significant neck/back pain (VAS ≤ 2; ODI ≤ 20), and no significant scoliosis (Cobb ≤ 20°). Radiographic measurements included commonly used coronal alignment parameters (mm) and angles (°). OD-CSVL was defined as the difference between the odontoid plumb line (line from the tip of the odontoid vertically down) and the CSVL (vertical line from the center of the sacrum). Chi-square, student's t tests, Kruskal-Wallis, Wilcoxon rank-sum, linear regression, and Pearson's correlation were used with significance at p < 0.05. RESULTS: 467 volunteers were included with normative OD-CSVL values by age decade, gender, BMI, and country. Mean ± SD OD-CSVL was 8.3 mm ± 6.5 mm and 31 (6.6%) volunteers were almost perfectly aligned (OD-CSVL < 1 mm). A linear relationship was seen between OD-CSVL with both age (p < 0.001) and BMI (p = 0.015). Significant variation was seen between OD-CSVL and 5 different ethnicities (p = 0.004). OD-CSVL correlated best with other coronal radiographic parameters, C7-CSVL (r = 0.743, p < 0.001), OD-knee (r = 0.230, p < 0.001), CAM-knee (r = 0.612, p < 0.001), and regional TL cobb angle (r = 0.4214, p = 0.005). CONCLUSION: Among asymptomatic volunteers, increased OD-CSVL was significantly associated with increased age, increased BMI, and ethnicity, but not gender. OD-CSVL correlated strongest with C7-CSVL, TL cobb angle, OD-knee, and CAM-knee. OD-CSVL. These results support further study of OD-CSVL in symptomatic adult spine deformity patients.

Is MIS-TLIF superior to open TLIF in obese patients?: A systematic review and meta-analysis.

PURPOSE: Obesity is a global health problem. It increases the risk of surgical complications and re-operations. While both MIS-TLIF and O-TLIF are reported to have comparably good long-term outcomes for non-obese patients, no consensus has been reached for obese patients. METHODS: A comprehensive search of the published literature was performed: PubMed, Scopus, Web of Science and Cochrane Central Register of Controlled Trials database in accordance to the PRISMA 2009 checklist. Data were collected with attention to baseline demographics, intra-operative blood loss, duration of surgery, surgical complications, hospitalization stay, VAS and Oswestry disability index (ODI) pre- and postoperatively. RESULTS: A total of 863 abstracts were identified from the databases, of which 4 articles were included in the meta-analysis. A total of 430 patients were identified, of which 217(50.5%) underwent the O-TLIF, while 213(49.5%) underwent MIS-TLIF. One hundred and ninety-four (45.1%) patients were males, while 236(54.9%) were females. The average age was 54.8 ± 12.0 years. The pooled BMI was 33.4 ± 4.7 for the open-TLIF group, and 32.7 ± 3.9 for MIS-TLIF group (p = 0.22). When comparing O-TLIF to MIS-TLIF: Patients who underwent O-TLIF had 383 mls more blood loss (95% CI: 329.5-437.4, p < 0.00001), 1.2-day longer hospitalization stay (95% CI: 0.80-1.62, p < 0.00001) and 3.8 times higher risk of dural tear (95% CI: 1.61-9.87, p = 0.003) when compared to MIS-TLIF patients. A trend toward higher postoperative wound infection rates (O-TLIF: 4.5%, MIS-TLIF: 2.4%) and an inferior improvement in ODI score (O-TLIF: 39.3, MIS-TLIF: 44.1) was found in O-TLIF patients when compared to MIS-TLIF patients. However, these were not statistically significant. CONCLUSION: MIS-TLIF is safe and may be a better option for lumbar fusion in obese patients. These slides can be retrieved under Electronic Supplementary Material.

Normal variation in sagittal spinal alignment parameters in adult patients: an EOS study using serial imaging.

PURPOSE: To describe normal variations in sagittal spinal radiographic parameters over an interval period and establish physiological norms and guidelines for which these images should be interpreted. METHODS: Data were prospectively collected from a continuous series of adult patients with first-episode mild low back pain presenting to a single institution. The sagittal parameters of two serial radiographic images taken 6-months apart were obtained with the EOS® slot scanner. Measured parameters include CL, TK, TL, LL, PI, PT, SS, and end and apical vertebrae. Chi-squared test and Wilcoxon Signed Rank test were used to compare categorical and continuous variables, respectively. RESULTS: Sixty patients with a total of 120 whole-body sagittal X-rays were analysed. Mean age was 52.1 years (SD 21.2). Mean interval between the first and second X-rays was 126.2 days (SD 47.2). Small variations (< 1°) occur for all except PT (1.2°), CL (1.2°), and SVA (2.9 cm). Pelvic tilt showed significant difference between two images (p = 0.035). Subgroup analysis based on the time interval between X-rays, and between the first and second X-rays, did not show significant differences. Consistent findings were found for end and apical vertebrae of the thoracic and lumbar spine between the first and second X-rays for sagittal curve shapes. CONCLUSIONS: Radiographic sagittal parameters vary between serial images and reflect dynamism in spinal balancing. SVA and PT are predisposed to the widest variation. SVA has the largest variation between individuals of low pelvic tilt. Therefore, interpretation of these parameters should be patient specific and relies on trends rather than a one-time assessment.

Delayed lymphocele formation following lateral lumbar interbody fusion of the spine.

PURPOSE: This paper aims to describe the rare post-operative complication of a lymphocele formation after lateral lumbar interbody fusion. METHODS: The patient in this case was a 76-year-old lady with a 10 year history of low back pain and neurogenic claudication. She had previously underwent multiple spine surgeries for her condition. She presented to our institution for a recurrence of her low back pain and right anterior thigh pain. She then underwent surgery in two stages; first, a mini-open lateral interbody fusion at L3/4 and L4/5; second, posterior instrumentation of T3 to S1 with sagittal spinal deformity correction. RESULTS: The patient recovered uneventfully in the initial post op period and was discharged within 8 days. However, she developed abdominal distension and discomfort 6 months after surgery. MRI and CT scan of her abdomen showed a retroperitoneal fluid collection compressing her left ureter, resulting in hydroureter and hydronephrosis. She was managed with a CT-guided drainage of the fluid collection. Fluid analysis was consistent with a lymphocele. Since the procedure, the patient has been asymptomatic for 2 years. CONCLUSIONS: Delayed lymphocele formation is a potential complication of lateral lumbar interbody fusion. When present, it can be managed conservatively with good results. This case suggests that surgeons should have a low threshold to investigate for a lymphocele development post-anterior or lateral lumbar spine surgery. The authors recommend the placement of a post surgical retroperitoneal drain, as it might assist in the early detection of a lymphocele formation.

Minimally invasive iliac screw fixation in treating painful metastatic lumbosacral deformity: a technique description and clinical results.

INTRODUCTION: Pelvic fixation via iliac screws is a crucial technique in stabilizing metastatic lumbosacral deformity. MIS iliac screw fixation avoids complications of an open approach and is a viable palliative option in treating patients with painful instability and advanced disease, unsuited for major reconstruction. In this paper we describe the use of MIS iliac screw fixation in treatment of painful metastatic LSJ deformity, highlighting our treatment rationale, selection criteria, technical experience and outcomes. METHODS: Five patients with lumbosacral metastatic deformity who underwent MIS lumbopelvic stabilization using iliac screws were prospectively studied. Patients had severe axial back pain in erect posture with significant resolution when supine. All patients had advanced disease with unfavorable tumor scores for major spinal reconstruction. RESULTS: Mean cohort age was 62 years. Median pre-op SIN and Tokuhashi scores were 13 and 9, respectively. All patients were instrumented successfully without conversion to open technique. Mean preoperative and postoperative Cobb angle was 11° and 5.4°, respectively. There were no neurological deficits or wound complications postop. Postoperative CT scans showed no iliac screw and sacroiliac joint bony violation. Mean time for commencement of adjuvant therapy was 2.8 weeks. Average follow-up was 13.2 months. No screw breakage, wound complication, symptomatic implant prominence and SI joint pain were noted at last follow-up. CONCLUSION: MIS iliac screw fixation is feasible, reproducible and can be employed without complications in metastatic spine. This opens a new avenue of surgical management for metastatic lumbosacral disease patients, who otherwise may be inoperable and provide better soft tissue control and earlier postoperative adjuvant treatment opportunity.

Versatility of percutaneous pedicular screw fixation in metastatic spine tumor surgery: a prospective analysis.

BACKGROUND: Posterior percutaneous spinal fixation (PPSF) has evolved to address the problems associated with metastatic spinal disease (MSD). This study was designed to evaluate the feasibility and spectrum of application of PPSF in the management of MSD, highlighting its clinical advantages. METHODS: Twenty-seven consecutive patients with MSD treated with PPSF in our institution from January 2011 to June 2014 were studied. After a multidisciplinary assessment, all patients were considered for surgical intervention due to clinical presentation of either neural deficit, skeletal instability, or both. Some of these patients belonged to the poor prognostic category based on survival prognostic scoring systems. The patients were categorized into seven groups depending on the modality of PPSF used. Demographic data, operative details, and clinical outcomes were investigated for each category and compared pre- and postoperatively. RESULTS: The median age was 60 years (range 49-78 years). Generally, all patients either maintained or improved their neurological status and achieved pain alleviation. Ambulatory status and Eastern Cooperative Oncology Group (ECOG) scores were improved using any modality of PPSF. The pure-stabilization group had the lowest amount of mean blood loss, shortest operative time, and intensive care unit (ICU) and hospital stays, while the long-construct group was observed to have the greatest amount of blood loss, and longest operative time and ICU stay. CONCLUSIONS: For patients with MSD, even with predicted poor prognosis on survival prognostic scoring systems, it is possible to improve functional outcomes and quality of life with PPSF, keeping surgical morbidity to a minimum. PPSF allows patients with pure spinal instability to be addressed successfully with least morbidity.

Increased matrix metalloproteinase-2 in ligamentum flavum hypertrophy and the regulation of MMP-2/TIMPs by elastin-derived peptides.

The study aimed to examine matrix metalloproteinase-2 (MMP-2) expression in a rat ligamentum flavum (LF) hypertrophy model in vivo, and the effect of elastin-derived peptides (EDPs) on MMP-2 and tissue inhibitors of metalloproteinases (TIMPs) in rat LF cells in vitro. Surgical destabilization was performed at the rat spinal L3/4 level to induce increased mechanical stress. Rats were killed at 6- and 12-weeks postsurgery for histological staining, immunohistochemical staining, RT-qPCR and western blot. 100 µg/mL EDPs were applied to isolated normal rat LF cells, with or without pretreatment of elastin receptor complex (ERC) inhibitors, to assess the expression of MMP-2, TIMP-1, and TIMP-2. Spinal destabilization led to LF hypertrophy, observed through increased LF thickness and area, along with histological changes of chondrometaplasia and elastic fiber degradation. LF was also stained positively for Col I and Col II, where elastic fiber has broken down. MMP-2 expression was notably elevated in the hypertrophied LF, accompanied by increased TIMP-2 and TIMP-3 levels. EDPs were found to suppress MMP-2 expression and reduce TIMP-1 and TIMP-2 levels in rat LF cells. Interestingly, exposure to EDPs led to a significant rise in MMP-2/TIMP-1 and MMP-2/TIMP-2 ratios, dependent on the ERC. Collectively, the study suggests that increased MMP-2 activity contributes to elastic fiber degradation in hypertrophied LF, generating EDPs that further enhance the MMP-2/TIMPs ratio in LF cells in an ERC-dependent manner. Further research is essential to delve into the mechanisms of EDPs in LF hypertrophy.

The Importance of Pelvic Obliquity in Assessing Spinal Coronal Alignment: Normative Values, Demographic, and Radiographic Correlations.

STUDY DESIGN: Prospective, cross-sectional study. OBJECTIVE: In a geographically diverse population of asymptomatic volunteers, we sought to report the incidence of pelvic obliquity (PO), establish normative values of PO across patient factors, and assess the correlation of PO with radiographic parameters. SUMMARY OF BACKGROUND DATA: PO is defined as the misalignment of the pelvis and can be assessed through several anatomic landmarks. Significant PO, whether caused by leg-length discrepancy or not, can lead to coronal malalignment which causes severe pain and disability. Significant emphasis has been placed on achieving appropriate sagittal alignment in recent decades; however, a greater understanding of coronal alignment is needed, and PO is a crucial aspect of evaluating the coronal plane in adult spinal deformity patients. METHODS: Asymptomatic adult volunteers, ages 18-80 years, enrolled patients from 5 countries (France, Japan, Singapore, Tunisia, and the United States) in the "multiethnic alignment normative study" cohort (IRB 201812144). The included volunteers had no known spinal disorder(s), no significant neck or back pain (Visual Analog Scale: ≤2; Oswestry Disability Index: ≤20), and no abnormal alignment (Cobb ≤20°). PO was measured in the frontal plane as the distance between the highest points of each acetabulum, calculated along the vertical axis in millimeters (mm). The incidence of PO was defined as PO ≥10 mm. Kruskal-Wallis, Wilcoxon rank-sum, Pearson correlation, and linear regression were used. RESULTS: A total of 467 patients were included, and PO values by age, sex, body mass index, and country were provided. The overall incidence of PO ≥10 mm was 4.3%, and a nonsignificant trend toward increased PO with age was seen ( P = 0.077). No significant differences were seen in PO between sex, ethnicity, or body mass index groups. No significant correlation existed between PO and other commonly used coronal radiographic measurements. CONCLUSION: PO ≥10 mm occurred in 4.3% of asymptomatic volunteers. Despite the importance of recognizing PO in preventing coronal malalignment, PO did not seem to be associated with other radiographic and demographic information, which underscores the importance of intentionally assessing for any PO before surgery. These results in an asymptomatic population provide a foundation for studying PO in patients with spinal pathology.

Silk fibroin-based complex particles with bioactive encrustation for bone morphogenetic protein 2 delivery.

Application of bone morphogenetic protein 2 (BMP-2) currently faces its challenges, and its efficacy of delivery has to be improved. The proper dosage of the powerful bioactive molecule is still under discussion and needs to be investigated further. In this work, pure silk fibroin particles and particles with calcium carbonate encrustation (complex particles) are designed, developed, and functionalized by BMP-2. These are used to deliver the bioactive molecule to mesenchymal stem cells (MSCs) to induce osteogenic differentiation. Results are compared with those of control groups of BMP-2 carriers under the same condition. Silk fibroin-based particles with size and component variations are prepared by self-assembly, desolvation, and soft template formation to improve BMP-2 loading efficiency. Results show that the particles significantly enhance osteogenic differentiation of MSCs, which is evident in the high ALP enzyme activity as well as the increased level of expression of osteogenic genes. Specifically, the combination of calcium compound and BMP-2 in the silk fibroin-calcium carbonate complex particles synergistically enhances osteogenesis. Release tests and mathematical modeling are applied to describe BMP-2 dissolution profiles, and the release mechanism is based on diffusion and polymer chain relaxation. In summary, the particles show high efficacies of BMP-2 delivery, and introduction of the complex particle can progressively enhance osteogenesis.

A Risk Quantification Reference Table for Progressed Adolescent Idiopathic Scoliosis Surgery: An Exact Case Matched Outcomes Analysis.

STUDY DESIGN: Retrospective Exact Matched case-control study. OBJECTIVES: Surgical treatment delay in AIS due to family preferences is common. This study aims to quantify the increase in risks as the Cobb angle increases and provide a Quantifiable Risk Reference Table that can be utilized for counseling. METHODOLOGY: AIS patients were divided into 3 groups: Group A: Cobb angle 50-60°, Group 61-70°, and Group CFinal ≥80°. Each patient in Group CFinal who had curve progression were then traced-back-in-time (TBIT) to review the clinical data at earlier presentations at 50-60° (C1), and 61-70° (C2). Patient demographics, radiological, operative, and outcomes data were compared between Group A vs C1 and Group B vs Group C2. RESULTS: A total of 614 AIS surgeries were reviewed. Utilizing the EM technique, a total of 302 AIS patients were recruited. There were 147, 111, 31, and 32 patients matched in Groups A, B, C1, and C2, respectively. C2 Final patients had 34% curve pattern change, 23.2% higher incidence of requiring two surgeries, and 17.3% increase in complications. There was a statistically significant increase of 2.4 spinal levels fused, 12% increase in implant density, 35% increase in operative time, 97% increase in intra-operative blood loss, 10% loss of scoliosis correction, 40% longer hospitalization stay, and 36% increase in costs for patients who had curve progression. CONCLUSION: This study is the first to use a homogenously matched AIS cohort to provide a Quantifiable Risk Reference Table. The Risk Table provides essential knowledge for treating physicians when counseling AIS patients.

The Utility of 'Minimal Access and Separation Surgery' in the Management of Metastatic Spine Disease.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To compare outcomes of percutaneous pedicle screw fixation (PPSF) to open posterior stabilization (OPS) in spinal instability patients and minimal access separation surgery (MASS) to open posterior stabilization and decompression (OPSD) in metastatic spinal cord compression (MSCC) patients. METHODS: We analysed patients who underwent surgery for thoracolumbar metastatic spine disease (MSD) from Jan 2011 to Oct 2017. Patients were divided into minimally invasive spine surgery (MISS) and open spine surgery (OSS) groups. Spinal instability patients were treated with PPSF/OPS with pedicle screws. MSCC patients were treated with MASS/OPSD. Outcomes measured included intraoperative blood loss, operative time, duration of hospital stay and ASIA-score improvement. Time to initiate radiotherapy and perioperative surgical/non-surgical complications was recorded. Propensity scoring adjustment analysis was utilised to address heterogenicity of histological tumour subtypes. RESULTS: Of 200 eligible patients, 61 underwent MISS and 139 underwent OSS for MSD. There was no significant difference in baseline characteristics between MISS and OSS groups. In the MISS group, 28 (45.9%) patients were treated for spinal instability and 33 (54.1%) patients were treated for MSCC. In the OSS group, 15 (10.8%) patients were treated for spinal instability alone and 124 (89.2%) were treated for MSCC. Patients who underwent PPSF had significantly lower blood loss (95 mL vs 564 mL; P < .001) and surgical complication rates(P < .05) with shorter length of stay approaching significance (6 vs 19 days; P = .100) when compared to the OPS group. Patients who underwent MASS had significantly lower blood loss (602 mL vs 1008 mL) and shorter length of stay (10 vs 18 days; P = .098) vs the OPSD group. CONCLUSION: This study demonstrates the benefits of PPSF and MASS over OPS and OPSD for the treatment of MSD with spinal instability and MSCC, respectively.

Prevalence and Risk Factors of Degenerative Spondylolisthesis and Retrolisthesis in the Thoracolumbar and Lumbar Spine - An EOS Study Using Updated Radiographic Parameters.

STUDY DESIGN: Single centre, cross-sectional study. OBJECTIVES: The objective is to report the prevalence of spondylolisthesis and retrolisthesis, analyse both conditions in terms of the affected levels and severity, as well as identify their risk factors. METHODS: A review of clinical data and radiographic images of consecutive spine patients seen in outpatient clinics over a 1-month period is performed. Images are obtained using the EOS® technology under standardised protocol, and radiographic measurements were performed by 2 independent, blinded spine surgeons. The prevalence of both conditions were shown and categorised based on the spinal level involvement and severity. Associated risk factors were identified. RESULTS: A total of 256 subjects (46.1% males) with 2304 discs from T9/10 to L5/S1 were studied. Their mean age was 52.2(± 18.7) years. The overall prevalence of spondylolisthesis and retrolisthesis was 25.9% and 17.1% respectively. Spondylolisthesis occurs frequently at L4/5(16.3%), and retrolisthesis at L3/4(6.8%). Majority of the patients with spondylolisthesis had a Grade I slip (84.3%), while those with retrolisthesis had a Grade I slip. The presence of spondylolisthesis was found associated with increased age (P < .001), female gender (OR: 2.310; P = .005), predominantly sitting occupations (OR:2.421; P = .008), higher American Society of Anaesthesiology grades (P = .001), and lower limb radiculopathy (OR: 2.175; P = .007). Patients with spondylolisthesis had larger Pelvic Incidence (P < .001), Pelvic Tilt (P < .001) and Knee alignment angle (P = .011), but smaller Thoracolumbar junctional angle (P = .008), Spinocoxa angle (P = .007). Retrolisthesis was associated with a larger Thoracolumbar junctional angle (P =.039). CONCLUSION: This is the first study that details the prevalence of spondylolisthesis and retrolisthesis simultaneously, using the EOS technology and updated sagittal radiographic parameters. It allows better understanding of both conditions, their mutual relationship, and associated clinical and radiographic risk factors.

Sagittal spinal alignment varies with an individual's race: results of the multi-ethnic alignment normative study (MEANS).

PURPOSE: Assess normative values of sagittal spinal and lower extremity alignment in asymptomatic volunteers of three difference races. METHODS: Asymptomatic volunteers between the ages of 18-80 years were enrolled prospectively and then analyzed retrospectively from six different centers. Volunteers included reported no significant neck or back pain, nor any known spinal disorder(s). All volunteers underwent a standing full-body or full-spine low dose stereoradiograph. Volunteers were grouped into three main races; Asian (A), Arabo-Bèrbère (B), and Caucasian (C). The Asian volunteers included in this study were from Japan and Singapore. RESULTS: There were statistical differences in the Age, ODI, and BMI of the volunteers from the three different races. Asian volunteers had the lowest age (A: 36.7, B: 45.5, C: 42.0) and BMI (A: 22.1, B: 27.1, C: 27.3). Pelvic morphology including pelvic incidence (A: 51.0, B: 52.0, C: 52.5, p = 0.37), pelvic tilt (A: 11.9, B: 12.3, C: 12.9, p = 0.44), and sacral slope (A: 39.1, B: 39.7, C: 39.6, p = 0.77) were similar amongst the 3 races. Regional spinal alignment was different between the groups. Thoracic Kyphosis (A: 32.9, B: 43.3, C: 40.0, p < 0.0001) and Lumbar lordosis (A: - 54.2, B: - 60.4, C: - 59.6, p < 0.0001) were lower in Asians compared to Caucasian and Arabo-Bèrbère volunteers despite having similar pelvic incidence. CONCLUSION: Volunteers in the Asian group had lower lumbar lordosis and thoracic kyphosis when compared to the Arabo-Bèrbère and Caucasian groups while all groups had similar pelvic morphology. Thoracic Kyphosis had no correlation with Pelvic Incidence, while Lumbar Lordosis correlated well with both Thoracic Kyphosis and Pelvic Incidence. Thoracic kyphosis may be an independent variable in establishing adequate lumbar lordosis and varies based on an individual's race.

Morphological description of sagittal lumbar spinal alignment using curve magnitude, span, and apex-the multiethnic alignment normative study (MEANS).

BACKGROUND CONTEXT: Current definition of lumbar lordosis uses the L1-S1 angle. Prevailing classification of sagittal spinal morphology, derived from a young adult population, classifies the spine into four subtypes defined by their sacral slope (SS) and curve morphology. PURPOSE: To describe physiological sagittal alignment of the lumbar spine across age groups using three main parameters that dictate the lumbar curve: angular magnitude, span, and apex. STUDY DESIGN: A large, multicenter, cross-sectional radiographic comparison study. PATIENT SAMPLE: Four hundred sixty-eight healthy, asymptomatic subjects aged 18 to 80 years from five countries (184 males, 284 females; 98 France, 119 Japan, 79 Singapore, 80 Tunisia, 92 USA, mean age 40.61±14.99 years). OUTCOME MEASURES: Sagittal lumbar profile subtypes clustered based on lumbar curve angular magnitude (ie, Cobb angle of the lumbar lordosis), span, and apex, and described by sagittal radiographic parameters. METHODS: Subjects underwent whole-body low-dose EOS stereoradiographs. Comparisons between conventional L1-S1 lumbar lordosis (cLL) and true lumbar lordosis (tLL, defined by the inflection-S1 angle) were conducted. Using the K-means clustering algorithm, lumbar curve angular magnitude, span and apex were used to classify sagittal spinal morphology into subtypes, stratified across age groups. Further univariate and multivariate analyses were conducted to compare radiographic parameters across subtypes, and identify predictors for the lumbar curve's angular magnitude, span and apex. RESULTS: Mean cLL was -57.27±11.37°, and tLL was -62.62±10.76°. Using tLL, instead of cLL, to describe sagittal spinal morphology, we found significant differences in terms of angular magnitude of the lumbar curve, the median thoracolumbar inflection vertebral level and pelvic incidence-lumbar lordosis mismatch Multivariate analysis found a larger SS, more positive T9 tilt, and more kyphotic T4-T12 predictive for a more lordotic tLL, while a larger overhang distance predicted for a less lordotic tLL (p-values<.001). In addition, a larger T9 tilt, less lordotic L1-L5 and smaller PT were predictors of a more caudal thoracolumbar inflection and lumbar apical vertebral levels (p-values<.001). Sagittal lumbar profiles of subjects age<30 years, 30≤age<60 years and age≥60 years, could be classified into 4, 6, and 3 subtypes, respectively. CONCLUSIONS: Sagittal lumbar profile subtypes vary across age groups, with more homogenous morphologies at the extremes of ages. Improved understanding of the morphological evolution of sagittal spinal profiles with age in asymptomatic individuals will help guide future individualized surgical treatment.

The Thoracolumbar Inflection Point in a Population of Asymptomatic Volunteers: A Multi-Ethnic Alignment Normative Study Cohort Study.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To show population variance in the Inflection Point (IP) and its role in defining maximum Thoracic Kyphosis (TK) and Lumbar Lordosis (LL). METHODS: 468 asymptomatic adult volunteers were included in the Multi-Ethnic Normative Alignment Study (MEANS). To find parameters correlating with IP, the vertebrae and discs were numbered such that C7 was 0, T1 was 1, with T1-T2 disc being 1.5, etc. Statistical analysis was performed by a correlation matrix for IP and the 9 other selected parameters along with linear regressions. RESULTS: The overall mean IP was 12.44 approximately corresponding to T12-L1 disc with the median being 12.50, range was T8-L4. The cohort was then stratified by sex and ethnicity, but there was no significant difference in IP between groups. IP in younger subjects was 13 (L1), compared to 12.5 (T12-L1 disc) in older subjects (P < .05). IP was moderately correlated with the TK apex (r = .66). No strong correlation was found between IP and LL magnitude or apex, TK magnitude, sacral slope, or Pelvic Incidence (PI). In terms of other sagittal parameters, PI and LL demonstrated a significant positive correlation. PI and TK did not have a strong association. CONCLUSIONS: The mean IP was at the T12-L1 disc, however IP ranged from T8 to L4. Older subjects tended to have a relatively more cephalad IP. No radiographic variable was found to be a strong predictor of the IP. TK apex was found to have a moderate correlation.