Cifosis patológica en la columna pediátrica / Pathologic kyphosis in the pediatric spine

En este manuscrito se revisan las diferentes causas que producen aumento de la cifosis torácica (dorso curvo), específicamente en niños y adolescentes. Las causas del dorso curvo que se analizan en este artículo son: Dorso curvo postural, idiopático, neuromuscular, congénito y enfermedad de Scheuermann. Se centra en los factores que producen su aparición, características de su evolución y tratamiento.

This manuscript reviews the different causes that lead to increased thoracic kyphosis, specifically in children and adolescents. The causes of increased thoracic kyphosis that will be discussed in this article are: postural, idiopathic, neuromuscular, congenital, and Scheuermann's disease. This paper focuses on the factors that produce its appearance, characteristics of its evolution, and treatment.

A single institution experience with proximal junctional kyphosis in the context of existing classification schemes - Systematic review.

BACKGROUND: Proximal junctional kyphosis is a kyphotic deformity following spine instrumentation, predominantly seen in scoliosis patients. There have been previous attempts to develop classification schema of PJK. We analyzed the factors contributing to PJK based upon our own clinical experience with the goal of developing a clinical guidance tool which took into account both etiology and mechanism of failure. METHODS: We performed a retrospective analysis of all re-operation thoracolumbar surgeries at a single institution over a 14-year period. Patients with PJK were identified and categorized based upon the etiology, mechanism of failure, and an indication of revision. Next, we conducted a systematic review on articles emphasizing a classification system for PJK. RESULTS: Fourteen PJK patients were identified out of 121 patients who required revision spine surgery. The average age was 64.9 ± 10.2 years, with 10 males (71%) and 4 females (29%). Three primary etiologies were identified: 6/14 (47%) overcorrection, 6/14 (47%) osteopenia, and 2/14 (14%) ligamentous disruption. The mechanism of failure was likewise divided into three categories: 9/14 (64%) compression fracture, 1/14 (7%) hardware failure, and 4/14 (29%) disc degeneration. The relationship between osteopenia and the development of a compression fracture leading to PJK was statistically significant (p = 0.031). CONCLUSION: There are multiple current classification systems for PJK. Our study findings were in line with previously published literature and suggest the need for a future classification system combining both etiology, mechanism of failure, and severity of disease.

Alignment, Classification, Clinical Evaluation, and Surgical Treatment for Adult Cervical Deformity: A Complete Guide.

Adult cervical deformity management is complex and is a growing field with many recent advancements. The cervical spine functions to maintain the position of the head and plays a pivotal role in influencing subjacent global spinal alignment and pelvic tilt as compensatory changes occur to maintain horizontal gaze. There are various types of cervical deformity and a variety of surgical options available. The major advancements in the management of cervical deformity have only been around for a few years and continue to evolve. Therefore, the goal of this article is to provide a comprehensive review of cervical alignment parameters, deformity classification, clinical evaluation, and surgical treatment of adult cervical deformity. The information presented here may be used as a guide for proper preoperative evaluation and surgical treatment in the adult cervical deformity patient.

Proximal Junctional Kyphosis According to the Type of Lumbar Degenerative Kyphosis Following Lumbosacral Long Fusion.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to investigate proximal junctional kyphosis (PJK) after lumbosacral long fusion according to preoperative Roussouly and lumbar degenerative kyphosis (LDK) types. SUMMARY OF BACKGROUND DATA: Although previous studies have suggested some risk factors for PJK, the effects of preoperative grade of sagittal imbalance and paraspinal muscles degeneration on PJK remain unclear. METHODS: Eighty-seven patients who had undergone lumbosacral fusion more than five levels with available clinical and radiological data were enrolled. The presence of PJK defined as sagittal Cobb angle ≥20° between the uppermost instrumented vertebra (UIV) and two supra-adjacent vertebrae at postoperative 2-year radiographs was recorded. Its occurrence was compared according to preoperative Roussouly and LDK types (Takemistu type) and the degree of paraspinal muscle degeneration at the upper level of UIV. Other sagittal radiographic parameters were also measured. RESULTS: In this series, 28 patients (group I, 32.2%) showed radiological PJK, whereas 59 patients did not show radiological PJK (non-PJK patients, group II, 67.8%) at postoperative 2 years. PJK presented more prevalence in type III and type IV of LDK types (26/27, 96.3%). However, Roussouly types did not show any significant difference in PJK prevalence. In radiological parameters, a larger preoperative SVA (P = 0.018) and PI-LL (P = 0.015) were associated with PJK. Also, smaller quantity and lower quality of paraspinal muscles at T12-L1 level showed significant (P < 0.001) relationship with PJK. On multivariate logistic regression, higher LDK type (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.24-3.56), smaller quantity (OR: 1.03, 95% CI: 1.00-1.07), and higher degree of paraspinal muscle degeneration (OR: 1.46, 95% CI: 0.92-2.31) were independent predictors of postoperative PJK. CONCLUSION: Although various factors are related to PJK following long segment fusion, preoperative conditions such as LDK types and degree of paraspinal muscle degeneration might be related to the development of PJK.Level of Evidence: 3.

Thoracolumbar Burst Fracture: McCormack Load-sharing Classification: Systematic Review and Single-arm Meta-analysis.

STUDY DESIGN: A systematic review and single-arm meta-analysis of randomized clinical trials. OBJECTIVE: The aim of this study was to evaluate whether the load-sharing classification (LSC) is reliable to predict the best surgical approach for thoracolumbar burst fracture (TBF). SUMMARY OF BACKGROUND DATA: There is no previous review evaluating the efficacy of the use of LSC as a guide in the surgical treatment of burst fractures. METHODS: On April 19th, 2019, a broad search was performed in the following databases: EMBASE, PubMed, Cochrane, SCOPUS, Web of Science, LILACS, and gray literature. This study was registered on the International Prospective Register of Systematic Reviews. We included clinical trials involving patients with TBF undergoing posterior surgical treatment, classified by load-sharing score, and that enabled the analysis of the outcomes loss of segmental kyphosis and implant failure (IF). We performed random- or fixed-effects models meta-analyses depending on the data homogeneity. Heterogeneity between studies was estimated by I2 and τ2 statistics. RESULTS: The search identified 189 references, out of which nine studies were eligible for this review. All articles presenting LSC up to 6 proved to be reliable in indicating that only posterior instrumentation is necessary, without screw failures or loss of kyphosis correction. For cases where the LSC was >6, only 2.5% of the individuals presented IF upon posterior approach alone. For loss of kyphosis correction, only 5% of patients had this outcome where LSC >6. For both outcomes together, we had 6% of postoperative problems (I2 = 77%, τ2 < 0.0015, P < 0.01). CONCLUSION: Load-sharing scores up to 6 are 100% reliable, only requiring posterior instrumentation for stabilization. For scores >6, the risk of implant breakage and loss of kyphosis correction in posterior fixation alone is low. Thus, other factors should be considered to define the best surgical approach to be adopted.Level of Evidence: 1.

More severe thoracic idiopathic scoliosis is associated with a greater three-dimensional loss of thoracic kyphosis.

STUDY DESIGN: Retrospective. OBJECTIVES: Utilize three-dimensional (3D) measurements to assess the relationship between thoracic scoliosis severity and thoracic kyphosis in a large, multicenter cohort, and determine impact of 3D measurements on adolescent idiopathic scoliosis (AIS) curve classification. Research has demonstrated differences in two-dimensional (2D) and 3D assessment of the sagittal plane deformity in AIS. A prior smaller, single-institution study demonstrated an association between scoliosis severity and loss of 3D thoracic kyphosis. METHODS: Data included retrospective compilation of prospectively enrolled bracing candidates and prospectively enrolled surgical candidates with thoracic AIS. Analysis included two groups based on thoracic curve magnitude: moderate (20-45°) and severe (> 45°). Imaging was performed using 2D radiographs. 3D thoracic kyphosis was calculated using a 2D to 3D conversion formula. Kyphosis was categorized according to the Lenke classification sagittal plane modifier. RESULTS: Analysis included 3032 patients. 2D kyphosis was significantly less in the moderate group (21 ± 12 vs 23 ± 14, p = 0.028). However, estimated 3D kyphosis was significantly greater in the moderate group (13 ± 10 vs 5 ± 12, p < 0.001). In the moderate group, the rate of normokyphosis was 78% with 2D measures and 61% with 3D measures of T5-T12 kyphosis. In the severe group, this rate changed from 72 to 32% with use of 2D and 3D measures, respectively. In the moderate group, 16% of patients were classified as hypokyphotic using 2D measures while this rate increased 38% with 3D measures (p < 0.001). In the severe group, this rate changed from 18 to 68% using 2D and 3D measures, respectively (p < 0.001). CONCLUSIONS: Increased coronal curve severity was associated with decreased thoracic kyphosis. Hypokyphosis was more pronounced in 3D. 2D radiographs increasingly underestimate kyphosis with increasing coronal severity. Assessment of sagittal alignment from 2D radiographs can be improved with a 2D-3D conversion formula. Findings indicate potential for classification system improvement with use of 3D sagittal plane measurements. LEVEL OF EVIDENCE: IV.

Degenerative changes of sagittal alignment in patients with Roussouly type 1.

STUDY DESIGN: A cross-sectional radiological study. OBJECTIVES: We aimed to examine the degenerative changes of sagittal alignment in patients with Roussouly type 1. Roussouly type 1 is unique in shape, characterized by short lumbar lordosis (LL) with the apex at L5 and thoracolumbar kyphosis (TLK). Because of the unique shape of sagittal alignment and the small pelvic incidence (PI) in Roussouly type 1, the degenerative changes of sagittal alignment may differ. METHODS: A total of 145 patients with Roussouly type 1 were recruited and distributed into three age groups; Group I (N = 40) were young patients (20-40 years of age), Group II (N = 47) were middle-aged patients (45-60 years of age), and Group III (N = 48) were elderly patients (>65 years of age). Sagittal parameters including sagittal vertical axis (SVA), PI, pelvic tilt (PT), L1S1 LL, L4S1 LL, thoracic kyphosis (TK), and TLK were measured using Surgimap® software. The occurrence of lumbar retrolisthesis was also examined. RESULTS: The SVA, PI, PT, L1S1 LL, L4S1 LL, TK, and TLK in group I were - 25.9° ± 23.4 mm, 37.1° ± 5.3°, 10.3° ± 5.5°, 42.7° ± 8.8°, 35.5° ± 6.9°, 29.5° ± 23.5°, and 9.7° ± 5.9°, respectively. Among the Groups I, II, and III, there was a stepwise increase in the SVA, PT, TLK, and lumbar retrolisthesis (all P < 0.001). The PI, L4S1 LL, and TK were identical among the three groups. CONCLUSIONS: Degenerative changes of Roussouly type 1 include increase in the SVA, PT, TLK, and lumbar retrolisthesis, while the PI, L4S1 LL, and TK remain unchanged. LEVEL OF EVIDENCE: Level IV.

Validation of a Simplified SRS-Schwab Classification Using a Sagittal Modifier.

STUDY DESIGN: Multicenter, prospective study of consecutive adult spinal deformity (ASD) patients. OBJECTIVE: To Validate Schwab's classification accuracy for surgical indication, and to evaluate a simplified sagittal modifier. SUMMARY OF BACKGROUND DATA: The SRS-Schwab Radiologic Classification based on clinical impact parameters, offers 27 different sagittal classification possibilities regarding sagittal vertical alignment (SVA), pelvic tilt (PT), and pelvic incidence-lumbar lordosis (PI-LL). The high number of classification possibilities makes it complex to use. METHODS: Inclusion criteria were ASD patients, presenting at least 1 criteria: Cobb ≥ 20°, SVA ≥ 5 cm, thoracic kyphosis ≥ 60°, or PT ≥ 25°. A total of 1,004 patients (410 nonoperative and 594 operative) were classified regarding SVA, PT, and PI-LL (0, +, ++), and 27 possibilities were identified. Categories were formed by adding the number of + signs, considering PT, SVA, and PI-LL. Three specific categories were identified: Aligned: 0 +; Moderate deformity: 1 to 3+; and Severe deformity: 4 to 6+. A χ-square test was performed for surgical indication (operated or not) and an analysis of variance was performed to evaluate the relationship between categories and Oswestry Disability Index (ODI). Probability <.05 was considered significant. RESULTS: Significant differences for HRQoL scores and surgical indication were found in the 27 sagittal parameter possibilities. For nonoperative patients, 230 (56.1%) were classified as aligned, 145 (35.4%) as moderate, and 35 (8.5%) as severe. For operative patients, there were 200 (33.7%), 215 (36.2%), and 179 (30.1%) in each respective subgroup. For HRQoL scores and surgical indication, no significant differences were found within each category, but significant differences were found when comparing the subgroups. CONCLUSIONS: Despite the correlation between SRS-Schwab classification and surgical indication, it is complex to use, with a total of 27 possibilities regarding sagittal modifiers. This simplification into three categories offers more readability, without losing any significant information, and could replace Schwab sagittal modifiers. In association with other parameters, they could be used for decision-making. LEVEL OF EVIDENCE: Level II.

A novel radiographic classification of severe spinal curvatures exceeding 100°: the Omega (Ω), gamma (γ) and alpha (α) deformities.

PURPOSE: For spine curvatures with Cobb angles > 100°, curve classification and characterization become more difficult with conventional radiographs. 3-D computerized axial tomography scans add relevant information to categorize and describe a new classification to aid preoperative assessment in communication and patient evaluation. The purpose of this study is to describe a radiographic classification system of curves exceeding 100°. METHODS: A consecutive series of patients with curves exceeding 100° underwent a full spine radiographic review using conventional radiographs and 3-D CT. A descriptive analysis was performed to categorize curves into 4 main types (1, 2, 3 and 4) and 6 subtypes (1C, 1S, 1CS, 2P, 2D and 2PD) based on the location of the Cobb angle of the major scoliotic and kyphotic deformity as well as the location of the upper/lower end vertebra relative to the apical vertebra. RESULTS: A total of 98 patients met the inclusion criteria. There were 51 males and 47 females with an average age of 17.8 ± 4.5 years. The diagnosis included idiopathic (48); congenital (24); neuromuscular (4); and neurofibromatosis (2). The mean major coronal and sagittal Cobb (kyphosis) were 131.2° ± 23.4° and 154 ± 45.6, respectively. The classification scheme yielded 4 main types (1, 2, 3 and 4) and 6 subtypes under types 1 and 2 (1C, 1S, 1CS, 2P, 2D and 2PD). CONCLUSIONS: Our study describes a novel method of classifying severe spinal curvatures exceeding 100° using erect AP/lateral radiographs and 3-D CT reconstructive images. We hope that the descriptive analysis and classification will expand our understanding of these complex deformities. These slides can be retrieved under Electronic Supplementary Material.

Recovery kinetics following spinal deformity correction: a comparison of isolated cervical, thoracolumbar, and combined deformity morphometries.

BACKGROUND CONTEXT: The postoperative recovery patterns of cervical deformity patients, thoracolumbar deformity patients, and patients with combined cervical and thoracolumbar deformities, all relative to one another, is not well understood. Clear objective benchmarks are needed to quantitatively define a "good" versus a "bad" postoperative recovery across multiple follow-up visits, varying deformity types, and guide expectations. PURPOSE: To objectively define and compare the complete 2-year postoperative recovery process among operative cervical only, thoracolumbar only, and combined deformity patients using area-under-the-curve (AUC) methodology. STUDY DESIGN/SETTING: Retrospective review of 2 prospective, multicenter adult cervical and spinal deformity databases. PATIENT SAMPLE: One hundred seventy spinal deformity patients. OUTCOME MEASURES: Common health-related quality of life (HRQOL) assessments across both databases included the EuroQol 5-Dimension Questionnaire and Numeric Rating Scale (NRS) back pain assessment. In order to compare disability improvements, the Neck Disability Index (NDI) and the Oswestry Disability Index (ODI) were merged into one outcome variable, the ODI-NDI. Both assessments are gauged on the same scale, with minimal question deviation. Sagittal Radiographic Alignment was also assessed at pre- and all postoperative time points. METHODS: Operative deformity patients >18 years old with baseline (BL) to 2-year HRQOLs were included. Patients were stratified by cervical only (C), thoracolumbar only (T), and combined deformities (CT). HRQOL and radiographic outcomes were compared within and between deformity groups. AUC normalization generated normalized HRQOL scores at BL and all follow-up intervals (6 weeks, 3 months, 1 year, and 2 year). Normalized scores were plotted against follow-up time interval. AUC was calculated for each follow-up interval, and total area was divided by cumulative follow-up length, determining overall, time-adjusted HRQOL recovery (Integrated Health State, IHS). Multiple linear regression models determined significant predictors of HRQOL discrepancies among deformity groups. RESULTS: One hundred seventy patients were included (27 C, 27 T, and 116 CT). Age, BMI, sex, smoking status, osteoporosis, depression, and BL HRQOL scores were similar among groups (p >. 05). T and CT patients had higher comorbidity severities (CCI: C 0.696, T 1.815, CT 1.699, p = .020). Posterior surgical approaches were most common (62.9%) followed by combined (28.8%) and anterior (6.5%). Standard HRQOL analysis found no significant differences among groups until 1-year follow-up, where C patients exhibited comparatively greater NRS back pain (4.88 vs. 3.65 vs. 3.28, p = .028). NRS Back pain differences between groups subsided by 2-years (p>.05). Despite C patients exhibiting significantly faster ODI-NDI minimal clinically important difference (MCID) achievement (33.3% vs. 0% vs. 23.0%, p < .001), all deformity groups exhibited similar ODI-NDI MCID achievement by 2-years (51.9% vs. 59.3% vs. 62.9%, p = 0.563). After HRQOL normalization, similar results were observed relative to the standard analysis (1-year NRS Back: C 1.17 vs. T 0.50 vs. CT 0.51, p < .001; 2-year NRS Back: 1.20 vs. 0.51 vs. 0.69, p = .060). C patients exhibited a worse NRS back normalized IHS (C 1.18 vs. T 0.58 vs. CT 0.63, p = .004), indicating C patients were in a greater state of postoperative back pain for a longer amount of time. Linear regression models determined postoperative distal junctional kyphosis (adjusted beta: 0.207, p = .039) and osteoporosis (adjusted beta: 0.269, p = .007) as the strongest predictors of a poor NRS back IHS (model summary: R2 = 0.177, p = .039). CONCLUSIONS: Despite C patients exhibiting a quicker rate of MCID disability (ODI-NDI) improvement, they exhibited a poorer overall recovery of back pain with worse NRS back scores compared with BL status and other deformity groups. Postoperative distal junctional kyphosis and osteoporosis were identified as primary drivers of a poor postoperative NRS back IHS. Utilization of the IHS, a single number adjusting for all postoperative HRQOL visits, in conjunction with predictive modelling may pose as an improved method of gauging the effect of surgical details and complications on a patient's entire recovery process.

Understanding Classification Systems in Spine Deformity.

Classification systems provide organization for pathologic conditions and guide treatment for similar disease states. Spine deformity is a growing field with newer classification systems being developed as our surgical techniques and clinical understanding advances. The evolution of these classification systems reflects our current knowledge and are used to better understand the evolving field of spine surgery. Currently, classification systems in spine surgery range from describing deformity in different age groups and different regions of the spine to describing various osteotomies and the severity of proximal junctional kyphosis. This paper will describe what makes a successful classification system in spine deformity. Old classification systems will be briefly described and their limitations that necessitated the need for newer classification systems. Newer systems will also be reviewed and the importance of specific radiographic parameters. Finishing this review, clinicians will be able to pick which systems are ideal for their practice.

A Classification for Kyphosis Based on Column Deficiency, Curve Magnitude, and Osteotomy Requirement.

BACKGROUND: There is a lack of a classification system providing uniformity in description and guiding management decisions for kyphotic spinal deformities. We developed such a classification based on column deficiency, flexibility of disc spaces, curve magnitude, and correlation with the corrective osteotomy required. METHODS: A classification was developed based on analysis of 180 patients with thoracolumbar kyphosis requiring osteotomy. The deformity was classified as Type I if the anterior and posterior columns were intact (IA indicated mobile disc spaces and IB, ankylosed segments). Type II indicated deficiency of only 1 column (IIA = anterior column and IIB = posterior column). Type III indicated deficiency of both columns (IIIA = kyphosis of ≤60°, IIIB = kyphosis of >60°, and IIIC = buckling collapse). A prospective analysis of 76 patients was performed to determine interobserver variability and the ability of the classification to guide selection of osteotomies of increasing complexity, including the Ponte osteotomy, pedicle subtraction osteotomy, disc bone osteotomy, single vertebrectomy, multiple vertebrectomies, and anterior in situ strut fusion procedure. RESULTS: The mean age of the 76 patients was 21.2 years, the mean kyphosis was 69.9° (range, 26° to 120°), and the mean follow-up duration was 30 months. Six deformities were classified as IA, 5 as IB, 5 as IIA, 2 as IIB, 13 as IIIA, 35 as IIIB, and 10 as IIIC. Four surgeons classifying the deformities had a high agreement rate (kappa = 0.83), with the highest agreement for Types IA, IB, and IIIB. A correlation between the type of deformity and the osteotomy performed demonstrated that the classification could indicate the type of osteotomy required. All 18 patients with Type-I or II kyphosis were treated with Ponte, pedicle subtraction, or disc bone osteotomy. Forty-three (90%) of the 48 patients with Type IIIA or IIIB underwent vertebrectomy (single in 27 [56%] and multiple in 16 [33%]), and only 5 (10%) underwent disc bone osteotomy. Seven of the 10 patients with Type-IIIC kyphosis were treated with multiple vertebrectomies, with 5 of them needing preoperative halo gravity traction; the other 3 patients underwent an anterior in situ strut fusion procedure. CONCLUSIONS: The proposed classification based on the morphology of column deficiency, flexibility, and curve magnitude demonstrated a high interobserver agreement and ability to guide selection of the appropriate osteotomy. CLINICAL RELEVANCE: A novel classification system for kyphosis based on spinal column deficiency, flexibility of disc spaces, and curve magnitude would bring uniformity in management and help guide surgeons in the choice of the appropriate corrective osteotomy.

Proposal of a New Treatment-Oriented Classification System for Spinal Deformity in Ankylosing Spondylitis.

OBJECTIVE: To describe and apply an optimal classification system for the management of ankylosing spondylitis (AS) that may be appropriate to make a preoperative surgical plan. BACKGROUND: The treatment choices of ankylosing spondylitis kyphosis remain controversial. The lack of a widely accepted classification system contributes to the variation in surgical decision making. METHODS: The classification is mainly based on radiographic findings. The sagittal deformity of spine in ankylosing spondylitis is classified according to three criteria: the location of the apex, the lumbar modifier (A, lumbar lordosis <0°, and B, lumbar kyphosis >0°) and the thoracic/thoracolumbar kyphosis severity modifier (- or +). RESULTS: The ankylosing spondylitis kyphosis can be divided into 4 types according to the location of the apex: Type I (lumbar), Type II (thoracolumbar), Type III (thoracic), Type IV (cervical or cervicothoracic junction). Either Type II or Type III is further divided into four subtypes based on the lumbar modifier and the thoracic/thoracolumbar kyphosis severity modifier: Type IIA-, Type IIA+, Type IIB-, Type IIB+, Type IIIA-, Type IIIA+, Type IIIB-, and Type IIIB+. Surgical decision making for AS kyphosis can be made according to the new classification. CONCLUSION: This new classification system can be used effectively to classify AS kyphosis, which can be used to guide surgical decision making, including determining the site and the levels of osteotomies. Further research may be needed to validate the classification.

Posterior paraspinal muscle versus post-middle approach for the treatment of thoracolumbar burst fractures: A randomized controlled trial.

BACKGROUND: This randomized controlled trial (RCT) aimed to compare the clinical outcomes of thoracolumbar burst fractures (TLBFs) treated with open reduction and internal fixation via the posterior paraspinal muscle approach (PPMA) and the post-middle approach (PA). METHODS: Patients with a traumatic single-level TLBFs (T10-L2), treated at our hospital between December 2009 and December 2014, were randomly allocated to Group A (PPMA) and Group B (PA). Sex, age, time from injury to surgery, the American Spinal Injury Association Impairment Scale score (ASIAIS), comorbidities, vertebral level, pre- and postoperative kyphotic angle (KA), visual analog scale (VAS) pain score, and the Oswestry Disability Index (ODI) scores were included in the analysis. Operative time, intraoperative blood loss, x-ray exposure time, postoperative drainage volume, superficial infection, and occurrence of deep infection were documented. The patients were followed up at 2 weeks; 1, 3, and 6 months; 1 and 2 years; and every 6 months thereafter. Radiological assessments were performed to assess fracture union and detect potential loosening and breakage of the pedicle screws and rods at each follow-up. Postoperative VAS and ODI scores were used to evaluate the clinical outcomes. RESULTS: A total of 62 patients were enrolled (30 in Group A and 32 in Group B, respectively). The operative time (P < .001) and x-ray exposure time (P < .001) in Group A were significantly longer than those in Group B. However, compared to Group B, there were less intraoperative blood loss (P < .001), lower postoperative drainage volume (P < .001), lower VAS scores (2-week (P = .029), 1-month (P = .023), 3-month (P = .047), and 6-month follow-up (P = .010)), and lower ODI scores (2-week, P = .010; 1-month, P < .001; 3-month, P = .028; and 6-month follow-up, P = .033) in Group A. CONCLUSIONS: Although PPMA required a longer operative time and x-ray exposure time, PPMA provided several advantages over PA, including less intra-operative blood loss and lower postoperative drainage volume, and greater satisfaction with postoperative pain relief and functional improvement, than PA, especially at the 6-month follow-up after surgery. Further high-quality multicenter studies are warranted to validate our findings.

The sagittal spinal profile type: a principal precondition for surgical decision making in patients with lumbar spinal stenosis.

OBJECTIVE Microsurgical decompression (MD) in patients with lumbar spinal stenosis (LSS) shows good clinical results. Nevertheless, 30%-40% of patients do not have a significant benefit after surgery-probably due to different anatomical preconditions. The sagittal profile types (SPTs 1-4) defined by Roussouly based on different spinopelvic parameters have been shown to influence spinal degeneration and surgical results. The aim of this study was to investigate the influence of the SPT on the clinical outcome in patients with LSS who were treated with MD. METHODS The authors retrospectively investigated 100 patients with LSS who received MD. The patients were subdivided into 4 groups depending on their SPT, which was determined from preoperative lateral spinal radiographs. The authors analyzed pre- and postoperative outcome scales, including the visual analog scale (VAS), walking distance, Oswestry Disability Index, Roland-Morris Disability Questionnaire, Odom's criteria, and the 36-Item Short Form Health Survey score. RESULTS Patients with SPT 1 showed a significantly worse clinical outcome concerning their postoperative back pain (VASback-SPT 1 = 5.4 ± 2.8; VASback-SPT 2 = 2.6 ± 1.9; VASback-SPT 3 = 2.9 ± 2.6; VASback-SPT 4 = 1.5 ± 2.5) and back pain-related disability. Only 43% were satisfied with their surgical results, compared with 70%-80% in the other groups. CONCLUSIONS A small pelvic incidence with reduced compensation mechanisms, a distinct lordosis in the lower lumbar spine with a high load on dorsal structures, and a long thoracolumbar kyphosis with a high axial load might lead to worse back pain after MD. Therefore, the indication for MD should be provided carefully, fusion can be considered, and other possible reasons for back pain should be thoroughly evaluated and treated.

The concurrent validity and intrarater reliability of the Microsoft Kinect to measure thoracic kyphosis.

This study aims to investigate the concurrent validity and intrarater reliability of the Microsoft Kinect to measure thoracic kyphosis against the Flexicurve. Thirty-three healthy individuals (age: 31±11.0 years, men: 17, height: 170.2±8.2 cm, weight: 64.2±12.0 kg) participated, with 29 re-examined for intrarater reliability 1-7 days later. Thoracic kyphosis was measured using the Flexicurve and the Microsoft Kinect consecutively in both standing and sitting positions. Both the kyphosis index and angle were calculated. The Microsoft Kinect showed excellent concurrent validity (intraclass correlation coefficient=0.76-0.82) and reliability (intraclass correlation coefficient=0.81-0.98) for measuring thoracic kyphosis (angle and index) in both standing and sitting postures. This study is the first to show that the Microsoft Kinect has excellent validity and intrarater reliability to measure thoracic kyphosis, which is promising for its use in the clinical setting.

Proximal Junctional Kyphosis.

Proximal junctional kyphosis (PJK) is a common complication following adult spinal deformity surgery. It is defined by two criteria: a proximal junctional sagittal Cobb angle (1) ≥ 10° and (2) at least 10° greater than the preoperative measurement. PJK is multifactorial in origin and likely stems from surgical, radiographic, and patient-related risk factors. The diagnosis of PJK represents a broad spectrum of disease ranging from asymptomatic patients with recurrence of deformity to those presenting with increased pain, functional deficit, and, in the most severe cases, neurologic deficits. Recent studies have demonstrated increased pain levels in select patients with PJK. In keeping with the broad spectrum of the disease, classification schemes are needed to better describe and stratify the severity of PJK. The most severe form is proximal junctional failure. A consensus on a uniform definition of proximal junctional failure is needed to allow for more systematic study of this phenomenon.

Analysis of the reliability of surgeons' ability to differentiate between idiopathic and degenerative spinal deformity in adults radiologically. What descriptive parameters help them decide?

PURPOSE: Adult spinal deformity (ASD) may be classified as idiopathic (ID) or degenerative (DD) (or other) based on classifier's perception, the reliability of and factors inherent to which remain unknown. The aim of this study is to evaluate the inter- and intra-observer reliability of surgeons' perception in differentiating ID from DD and to identify the determinants of this differentiation. METHODS: From a multicentric prospective database of ASD, 179 patients were identified with the diagnosis of ID (n = 103) or DD (n = 76); without previous surgery; and a lumbar coronal curve larger than 20°. Standing antero-posterior and lateral X-rays of these patients were sent to five experienced spine surgeons to be identified as DD or ID (or other); followed by a second round after reshuffling. Weighted kappa statistics were used, the strength of agreement for the kappa coefficient was considered as; 0.81-1 = almost perfect, 0.61-0.8 = substantial, 0.41-0.60 = moderate, 0.21-0.40 = fair, 0.01-0.20 = slight, and ≤0 = poor. Patients were then stratified based on the number of agreements on a total of 10 rounds as excellent (10 out of 10), good (more than 7 out of 10) and fair/poor (7 and less). These excellent and good agreements were further compared for additional radiological parameters. RESULTS: Agreement levels were moderate to substantial for intra but mostly fair for inter-observer comparisons. For ID patients, there were 42 cases with excellent and 38 with very good agreement whereas for DD, there were no excellent and only 17 cases with very good agreement. Upon comparison of these (ID vs DD for at least very good cases), it was seen that they were different for some coronal parameters such as lumbar Cobb angle (larger in ID, p < 0.001), central sacral vertical line (CSVL) modifier (C more common in ID, p = 0.007) and presence of rotatory subluxation (less common in DD, p = 0.017), but very different for sagittal parameters (lumbar lordosis, sagittal vertical axis, T2 sagittal tilt, pelvic tilt, sacral slope, and global tilt; increased sagittal imbalance in DD, all p ≤ 0.001). CONCLUSION: Surgeons in this study demonstrated reasonable (moderate to substantial) intra-observer agreement, but only fair agreement amongst them. Alarming as it may appear, we should be cautious in interpreting these results based on only radiology and no clinical information. In patients with good agreement, the most consistent radiologic determinant of degenerative ASD appeared to be the presence of sagittal imbalance.

Results of the 2014 SRS Survey on PJK/PJF: A Report on Variation of Select SRS Member Practice Patterns, Treatment Indications, and Opinions on Classification Development.

STUDY DESIGN: An electronic survey administered to Scoliosis Research Society membership. OBJECTIVE: To characterize surgeon views regarding proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) management providing the framework in which a PJK/PJF classification system and treatment guidelines could be established. SUMMARY OF BACKGROUND DATA: PJK/PJF are common complications of adult spinal deformity surgery. To date, there is no consensus on PJK/PJF definitions, classification, and indications for revision surgery. There is a paucity of data on deformity surgeon practice pattern variations and consensus opinion on treatment and prevention. METHODS: An electronic 19-question survey regarding PJK/PJF was administered to members of the Scoliosis Research Society who treat adult spinal deformity. Determinants included the surgeons' type of practice, number of years in practice, agreement with given PJK/PJF definitions, importance of key factors influencing prevention and revision, prevention methods currently used, and the importance of developing a classification system. RESULTS: A total of 226 surgeons responded (38.8% response rate). Both 44.4% of surgeons selected "extremely important" and 40.8% selected "very important" that PJK in adult spinal deformity surgery is a very important issue and that a Scoliosis Research Society PJK/PJF classification system and guidelines for detection and prevention of PJK/PJF is a "must have" (18.1%) and "very likely helpful" (31.9%). Both 86.2% and 90.7% of surgeons agreed with the provided definitions of PJK and PJF, respectively. Top 5 revision indications included neurological deficit, severe focal pain, translation or subluxation fracture, a change in kyphosis angle of greater than 30°, chance fracture, spondylolisthesis greater than 6 mm, and instrumentation prominence. The majority of respondents use a PJK/PJF prevention strategy 60% of the time or more, the most common were terminal rod contour, preoperative bone mineral density testing, and frequent radiographical studies during first 3 months postoperative, preoperative bone mineral density medication for low bone mineral density. CONCLUSION: The results of this study provide insight from the practicing surgeons' perspective of the management of PJK and PJF that may aid in the validation of current definitions and consensus-based treatment decisions and prevention guidelines. LEVEL OF EVIDENCE: 5.

Implant distribution in surgically instrumented Lenke 1 adolescent idiopathic scoliosis: does it affect curve correction?

STUDY DESIGN: Retrospective review of prospective multicenter database of patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion. OBJECTIVE: To analyze implant distribution in surgically instrumented Lenke 1 patients and evaluate how it impacts curve correction. SUMMARY OF BACKGROUND DATA: Although pedicle screw constructs have demonstrated successful surgical results, the optimal pedicle screw density and configuration remain unclear. METHODS: A total of 279 patients with adolescent idiopathic scoliosis treated with pedicle screws were reviewed. Implant density was computed for each side of the instrumented segment, which was divided into 5 regions: distal and proximal ends (upper/lower instrumented vertebra +1 adjacent vertebra), apical region (apex ± 1 vertebra), and the 2 regions in between (upper/lower periapical). Centralized measurement of Cobb angle and thoracic kyphosis was performed on preoperative and at 1-year postoperative radiographs as well as percent curve flexibility. RESULTS: The mean implant density was 1.66 implants per level fused (1.08 to 2) with greater available pedicles filled on the concavity (92%, 53%-100%) compared with the convex side (73%, 23%-100%, P < 0.01). The concave distal end region had the highest density with 99% of pedicles filled (P < 0.01), followed by the other concave regions and the convex distal end region (88%-94%) (P > 0.05). Other convex regions of the construct had less instrumentation, with only 54% to 78% of pedicles instrumented (P < 0.01). Implant density in the concave apical region (69%, 23%-100%) had a positive effect on curve correction (P = 0.002, R = 0.19). CONCLUSION: Significant variability exists in implant distribution with the greatest variation on the convex side and lowest implant density used in the periapical convex regions. Only instrumentation at the concave side, particularly at the apical region, was associated with curve correction. This suggests that for a low implant density construct, the best regions for planned screw dropout may be in the periapical convexity. LEVEL OF EVIDENCE: 3.