Roussouly Type Research Articles

Sagittal Alignment in Patients with Thoracic Myelopathy Caused by the Ossification of the Ligamentum Flavum: A Retrospective Matched Case-Control Study.

Retrospective case-control study. The aim of this study was to describe and compare the sagittal spinal alignment between patients with and without the ossification of the ligamentum flavum in the thoracic spine (TOLF). Although mechanical factors play an important role in the development of TOLF, limited evidence exists on the association of sagittal spinal alignment and TOLF in the literature. The present study assessed the preoperative sagittal alignment parameters in consecutive patients who underwent posterior decompression for TOLF in a single institution between January 2014 and December 2019. The sagittal parameters of the patients with TOLF were compared to those of the age- and sex-matched control group with lumbar spondylosis. The TOLF group (n = 43 [23 men, 20 women]), with a mean age of 69.5 (range: 41-86) years, and the control group (n = 86) were compared. The TOLF group had a significantly smaller sacral slope (27.60 ± 7.49 vs. 30.61 ± 8.15, P = 0.045) and lumbar lordosis (36.84 ± 13.63 vs. 45.08 ± 9.90, P < 0.001) and a larger pelvic incidence minus lumbar lordosis (PI-LL, 8.06 ± 15.05 vs.1.00 ± 11.34, P = 0.004) than the control group. Moreover, the thoracic kyphosis was smaller in the TOLF group, although the difference was not statistically significant (25.73 ± 11.29 vs. 28.22 ± 9.34, P = 0.187). The TOLF group had a significantly smaller slope angle at the inflection point (11.97 ± 5.85 vs. 15.78 ± 5.62, P < 0.001) and a higher tendency to have a Roussouly type 2 morphology (46.5% vs. 36.0%, P = 0.252) than the control group. This is the first study to describe the sagittal alignment in patients with TOLF. The TOLF group showed a hypolordotic spine with a larger PI-LL mismatch compared to the age- and sex-matched control group with lumbar spondylosis.Level of Evidence: 4.

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

A retrospective study. 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. 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. 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. 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. 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.

Variations of Sagittal Alignment in Standing Versus Sitting Positions Under the Roussouly Classification in Asymptomatic Subjects.

Study Design:Prospective radiological analysis.Objective:To investigate the characteristics of the sagittal spinopelvic alignment in the standing and sitting positions under the Roussouly classification in a healthy population.Methods:This study using standing and sitting lateral radiographs included 143 volunteers whose spinopelvic parameters were measured. The parameters were compared in the standing and sitting positions. The lumbo-pelvic profile was identified according to the Roussouly classification. The differences in the values of the parameters between the standing and sitting positions were analyzed. The different frequencies of the unchanged apex were assessed.Results:All parameter values except the thoracolumbar angle (TLK) were significantly altered. With regard to the classification of the lumbopelvic profile, 15 (10.5%) subjects were excluded because they were evaluated as not belonging to any of the Roussouly types. The remaining 128 subjects were evaluated and classified as follows: 19 (14.8%), type 1; 53 (41.4%), type 2; 9 (7.0%), type 3 + anteverted pelvis (AP); 33 (25.8%), type 3; and 14 (10.9%), type 4. The differences in the pelvic tilt (PT), sacral slope (SS), and thoracic pelvic angle (TPA) values were significantly lower in types 1 and 2 than in other Roussouly types. Corresponding variations in the apical vertebra for the sagittal lumbar curves in the sitting position were observed.Conclusions:Subjects with Roussouly type 1 and type 2 sagittal alignments were found to be less capable of performing changes in alignment when changing to the sitting position. The characteristics of the apical movement were also different.

Revision Surgery for Adjacent Segment Degeneration After Fusion for Lumbar Spondylolisthesis: Is there a Correlation with Roussouly Type?

Retrospective study. The aim of this study was to investigate whether there is an association between revision surgery rates for adjacent segment degeneration (ASD) and Roussouly type after L4-5 transforaminal lumbar interbody fusion (TLIF) for spondylolisthesis. Revision surgery for ASD is known to occur after spinal fusion; however, it is unclear whether rates of ASD are associated with certain Roussouly types. Patients who underwent L4-5 TLIF for spondylolisthesis at the University of California San Francisco from January 2006 to December 2016 with minimum 2-year follow-up were retrospectively analyzed by Roussouly type. Revision surgery for ASD was noted and correlated by Roussouly type. Spinopelvic parameters were also measured for correlation. A value of P < 0.05 was significant. There were 174 patients who met inclusion criteria, (59 males and 115 females). The average age was 62.3 (25-80) years. A total of 132 patients had grade I spondylolisthesis, and 42 had grade II. Mean follow-up was 45.2 months (24-497). A total of 22 patients (12.6%) underwent revision surgery for ASD after L4-5 TLIF. When classified by Roussouly type, revision surgery rates for ASD were: 1, 14.3%; 2, 22.6%; 3, 4.9%; and 4, 15.6% (P = 0.013). Type 3 spines with normal PI-LL (8.85° ± 6.83°) had the lowest revision surgery rate (4.9%), and type 2 spines with PI-LL mismatch (11.06° ± 8.81°) had the highest revision surgery rate (22.6%), a four-fold difference (P = 0.013). The PI-LL mismatch did not change significantly in each type postoperatively (P > 0.05). We found that there may be a correlation between Roussouly type and revision surgery for ASD after L4-5 TLIF for spondylolisthesis, with type 2 spines having the highest rate. Spinopelvic parameters may also correlate with revision surgery for ASD after L4-5 TLIF.Level of Evidence: 4.

28. Does baseline thoracolumbar shape influence patterns of cervical decompensation following surgical adult spinal deformity correction?

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery is complex and may lead to new-onset cervical malalignment and/or proximal junctional kyphosis (PJK). Roussouly et al describes variations in baseline thoracolumbar (TL) shape (Types 1-4), which have been shown to differentially influence surgical ASD outcomes. The effect of morphological shape on patterns of postoperative CD development remains underexplored. PURPOSE Stratify patients by Roussouly type and assess patterns of conversion from baseline (BL) cervical alignment to postoperative cervical deformity (CD) in patients undergoing thoracolumbar ASD surgery. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter database of ASD patients. PATIENT SAMPLE A total of 266 surgical ASD patients. OUTCOME MEASURES Rate and timing of conversion to CD, rate of PJK, radiographic alignment parameters. METHODS Operative ASD patients with complete radiographic data at baseline, 6W, 1Y, 2Y, & 3Y intervals were included. Patients were grouped by baseline PI and apex of LL into component types of the Roussouly classification system utilizing pelvic incidence as published by Pizones et al. Patients with no BL CD were postoperatively stratified by Ames CD criteria (TS-CL>20 °, cSVA>40mm), where CD was defined as fulfilling >1 criteria. Follow-up intervals were established post-ASD surgery, with 6W postop defined as “Early,” 6W-1Y “Intermediate,” 1-2Y “Late,” and 2-3Y “Long.” Univariate and Cox regression analyses identified CD conversion rate and PJK rate ( RESULTS A total of 266 surgical ASD patients (59.7yrs, 77.4% F) with complete radiographic data were included. By Roussouly classification, 9% were Type 1, 15.8% Type 2, 46.6% Type 3, and 28.6% Type 4. 28.6% of ASD patients converted to postop CD (Early: 14.3%, Intermediate: 5.3%, Late: 4.1%, Long: 4.9%). There were no significant differences in CD conversion rate across Roussouly types (1: 33.3%; 2: 28.6%; 3: 26.6%; 4: 30.3%, P=0.895). Types 2 (41.7%), 3 (60.6%), and 4 (43.5%) had their peak rates of conversion in the Early ( 1 year) than other types (50% vs 28.1%, P=0.135), while Type 1 patients trended higher rates of earlier CD conversion ( 0.05). There were no significant change in ODI, PCS, or SRS total among Roussouly Types in patients that converted to CD (p>0.05). Random forest analysis determined the top surgical (levels fused), radiographic (TS-CL), and demographic (frailty) factors associated with CD conversion. CONCLUSIONS Baseline thoracolumbar shape as described by the Roussouly classification has a differential effect on timing to CD conversion, though overall rates of CD conversion after TL-ASD correction were similar across Types 1-4. Type 1 patients with a lower apex of lumbar lordosis trended earlier conversion, while Type 2 patients with a higher apex of LL trended conversion beyond 1-year postop. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

20. Achievement of optimal clinical outcomes in adult spinal deformity surgery requires prioritizing realignment goals and varies based on pelvic incidence

BACKGROUND CONTEXT Many patients are unable to undergo a major adult spinal deformity (ASD) corrective surgery due to deformity severity, age, comorbidities, and overall frailty status. In order to optimize quality of life in patients with ASD there may be alignment ratios to be prioritized across different presentations of spinal shape. PURPOSE To prioritize radiographic alignment ratios for alignment. STUDY DESIGN/SETTING Retrospective review of a single surgeon adult spinal deformity database. PATIENT SAMPLE A total of 165 patients undergoing ASD corrective surgery OUTCOME MEASURES Minimal clinically important difference (MCID) for SRS-22r and Oswestry Disability Index (ODI); proximal junctional kyphosis (PJK). METHODS Included: patients >18yrs undergoing surgery for ASD (scoliosis ≥20°, SVA ≥5cm, PT ≥25°, or TK ≥60°) with full baseline (BL) and 2-year (2Y) radiographic parameters and HRQL scores. Patients were stratified by baseline pelvic incidence: low PI ( RESULTS A total of 165 ASD patients included (56.7±16.3yrs, 80.3% female, 25.8±5.3kg/m2). By approach, anterior: 0.6%, posterior: 91.2%, and combined approach: 8.2%. Average levels fused: 11.3±4.1, operative time: 332 min, estimated blood loss: 1,968 ccs. By baseline PI: 24.3% low PI, 75.7% high PI. (47 patients) of patients met the criteria for BCO, which was evenly distributed among the Roussouly types (p=0.115). For low PI patients, a combination of correcting the PI-LL from 0-25%, SVA 75-100%, and PT 0-25% significantly predicting acquiring the BCO (R2 =0.622, p=0.002). For BCO in high PI patients, a 25-50% correction in PI-LL, SVA minimal, and PT 75-100% (R2 =0.297, p=0.021). Low PI patents who met the three ratios of correction (PI-LL, SVA and PT) had less major complications (11.1% vs 23.1%) compared to other low PI patients. High PI patients who were corrected to the Schwab quartile of ratios underwent less reoperations (6.1% vs 23.3%) and had less PJK occurrence by 2-years postop (20.4% vs 40%), all p CONCLUSIONS Certain ratios of correction of the SRS-Schwab modifiers contribute to improving clinical outcomes and vary by preoperative spinal shape. Prioritization of global realignment relative lumbo-pelvic mismatch depends on the theoretical contour of the individual patient. Importantly, certain subgroups experience the most clinical benefit from the initial percentages of realignment, which may obviate more aggressive corrections on an individual basis. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

118. The incremental clinical benefit of adding layers of complexity to the planning and execution of adult spinal deformity corrective surgery

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, determining optimal restoration of alignment and spinal shape have been increasingly studied. Temporally, the SRS-Schwab classification system was the first severity categorization system. Next, the age-adjusted alignment was proposed, followed by Roussouly classification, and then a spinal proportionality score to minimize mechanical complications. These additional layers of complexity add to an already technically challenging and high risk case. What hasn't been determined is the incremental benefit of these. PURPOSE To assess the incremental benefits of adding ASD surgical corrective measures on patient-reported outcomes. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE This study included 732 ASD patients. OUTCOME MEASURES Complications; health related quality of life (HRQL). METHODS ASD patients with baseline (BL) and 2-year postoperative (2Y) data included. Patients were classified by the four proposed corrective alignment measures: SRS-Schwab: PT, SVA and PI-LL(0, +, and ++); Age-adjusted: PT, PI-LL, and SVA-adjusted ideal; Roussouly type: ‘Match’ or ‘Mismatch,’ their theoretical type; spinal proportionality: sagittal disproportion score out of 13. Alignment improvement: SRS-Schwab 0 or decrease in severity, Age-adjusted ideal match, Roussouly theoretical Match, and decrease in proportion. To assess the incremental benefit of layers of complexity, patients were separated into 4 groups: the first layer (1st) solely improving in SRS-Schwab at 2Y, 2nd as Schwab improvement and matching Age-adjusted, 3rd as the two prior with matching of Roussouly, and 4th improvement in Schwab and proportionality, as well as matching both Age-adjusted ideals and Roussouly. Comparison was accomplished with means comparison tests and chi-squared analyses. RESULTS A total of 732 ASD patients (57.5yrs, 82.4%F, 27kg/m2) included. SRS-Schwab BL: PI-LL (++:32.9%), SVA (++: 23%), PT (++:24.6%). At 2 year, 54.9% improved in PT modifier, 71% SVA, 74.3% PI-LL. For Age-adjusted ideal, 28% met PT ideal, 18.8% PI-LL, and 31.3% SVA. By 2 years, 44.7% matched Roussouly types. At 2 years, 30.8% improved in spine proportion. According to layer of correction complexity groups: 640 (87.4%) met criteria for first, 517 (70.6%) 2nd, 176 (24%) 3rd, and 55 (7.5%) 4th. When comparing the incremental adding of the second layer, or age-adjusted ideals to Schwab improvement, complications and HRQLs were similar (p>0.05). Addition of Roussouly (third) had less mechanical complications and PJK (48.3%), and met MCID for PCS and SRS-Mental (p CONCLUSIONS Consideration of multiple complex realignment techniques, taking into account deformity severity, age, shape, and spinal proportion, may assist in optimizing patient-reported outcomes following spinal realignment surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

The heritability of coronal and sagittal phenotype in idiopathic scoliosis: a report of 12 monozygotic twin pairs

PurposeOne of the pathways through which genetics may act in the causation of idiopathic scoliosis is inheritance of a specific sagittal profile that predisposes for its development. In this study, coronal and sagittal parameters were compared in an international collection of monozygotic twins with idiopathic scoliosis.MethodsTwelve monozygotic twin pairs who underwent biplanar radiography for idiopathic scoliosis were systematically identified in existing scoliosis databases in The Netherlands, Sweden, and Denmark. On the first available radiographs, the coronal and sagittal curve parameters (Roussouly and Abelin types, thoracic kyphosis, lumbar lordosis and length of the posteriorly inclined segment) were determined.ResultsIn all 12 monozygotic twin pairs, both twins were affected by AIS. Four (33%) twin pairs had similar coronal and sagittal spinal phenotype, whereas two (17%) had different coronal phenotype and similar sagittal profiles, and six (50%) pairs had different coronal as well as sagittal phenotype.ConclusionsAnalysis of biplanar curve characteristics in monozygotic twins showed that all twin pairs were affected by idiopathic scoliosis. However, only 33% of the pairs had similar coronal and sagittal spinal phenotypes. Based on this limited dataset, the hypothesis can be formulated that besides genetic pre-disposition, the individual (inherited) sagittal profile plays a role in the development of different coronal curve type.

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

A cross-sectionalradiologicalstudy. 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. A total of 145 patients with Roussouly type 1 were recruited and distributed into three age groups; Group I (N = 40) were young patients (20-40years of age), Group II (N = 47) were middle-aged patients (45-60years of age), and Group III (N = 48) were elderly patients (>65years 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. The SVA, PI, PT, L1S1 LL, L4S1 LL, TK, and TLK in group I were - 25.9° ± 23.4mm, 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. 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 IV.

SPINOPELVIC VARIABILITY ACCORDING TO THE ROUSSOULY CLASSIFICATON CURVE TYPE

ABSTRACT Objective To evaluate the variability of spinopelvic sagittal parameters and the distribution of lordosis in the lumbar spine in a sample of patients. Methods This is a cross-sectional study considering full-spine radiographs of a patient sample. The patients were classified according to the Roussouly classification and both radiographic spinopelvic alignment parameters and the lordosis measurement of each lumbar spinal segment were considered. The radiographic parameters were correlated with the Roussouly classification type. Results Ninety patients were included in the study. There was significant correlation between pelvic incidence (PI) and lumbar lordosis (LL) (R=0.89; p&lt;0.0001). The values of PI were significantly higher in Roussouly types 3 and 4 than in types 1 and 2 (p&lt;0.001), as were the values of LL L1-S1(p&lt;0.001). Considering the total sample, 67% of LL L1-S1 was located between L4-S1, but with variations by the Roussouly classification curve types. Conclusion This study demonstrated a high correlation between the values of PI and LL, as well as the importance of the distal lumbar segment (L4-S1) in the overall value of LL L1-S1, which was even higher in patients with a lower PI value (Roussouly types 1 and 2). Level of evidence II; Retrospective analysis of a prospective database (Cohort); Diagnostic study.

Analysis of Lumbar Sagittal Curvature in Spinal Decompression and Fusion for Lumbar Spinal Stenosis Patients under Roussouly Classification.

To evaluate the clinical significance of spinal decompression and fusion for lumbar spinal stenosis in old patients under Roussouly classification, 160 old patients (>60 year old) with lumbar spinal stenosis underwent spinal decompression, and fusion were retrospectively studied. According to Roussouly classification, patients were divided into 4 groups, in which Roussouly types I, II, and IV were the nonstandard group and Roussouly type III was the standard group. Visual analog scale (waist, leg) and Oswestry disability index (ODI) scores were recorded before operation and at the final follow-up. All patients improved the sagittal curvature: for patients in Roussouly types I and II, there were statistically significant differences in terms of postoperative global lordosis (GL), global kyphosis (GK), sacral slope (SS), sagittal vertical axis (SVA), and pelvic tilt (PT) compared with that before surgery (all P < 0.001); patients in Roussouly type IV obtained similar results with type III after surgery. The four groups showed significant improvement in ODI and VAS scores at final follow-up (all P < 0.001). After regrouping at the final follow-up, the proportion of the standard type (Roussouly type III) patients was increased compared with preoperative. In conclusion, Roussouly classification has important guiding significance in spinal decompression and fusion for old patients (>60 years) with lumbar spinal stenosis.

Characterization of Sagittal Spine Alignment With Reference to the Gravity Line and Vertebral Slopes: An Analysis of Different Roussouly Curves.

Prospective study. To map the healthy standing alignment of the adult spine, grouped according to Roussouly curve types, using both horizontal offset distance from the gravity line (GL), as well as vertebral slope measurements. Spinal sagittal realignment requires a reference posture, and this has been defined in the literature via horizontal offsets from the GL. While useful, this does not provide information on the orientation of each vertebral segment, or distinguish between the various physiological curve types. A total of 169 consecutive young adult subjects with healthy spines were recruited over a year. (EOS Imaging, Paris, France) whole body radiographs were performed. Radiographic measurements collected included sagittal vertical axis (SVA), T1-slope, global cervical angle (GCA), global thoracic angle (GTA), global lumbar angle (GLA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), apical and inflection vertebrae. Outcome measures comprised slope measurements, and distance offsets relative to the GL for individual vertebrae from T3 to S1. GLA, PI, PT, SS, apex of lordosis, and inflection vertebra were significantly different across groups, while SVA, T1-slope, GCA, GTA, and apex of kyphosis were not. Mean PI to LL discrepancy for Type I to IV groups were 8.0°, 2.3°, 4.8°, and 3.0°, respectively. Between groups, T3, T7 to T12, and L2 to S1 slopes and T9 to L3 offset distances from GL were significantly different, while the distance of the hip center from the GL was not. GLA was significantly different between curve types except between Type 1 and 2 curves, while the inflection vertebrae were not significantly different between Type 1 and 2 curves, as well as Type 3 and 4 curves. This study demonstrates normative sagittal spatial orientation of each vertebra in healthy adults, for each Roussouly type. Comparison across groups suggests the possibility of further refining the sagittal curve patterns described by Roussouly. 3.

Combined percutaneous and open instrumentation for thoracolumbar kyphosis correction by two-level pedicle subtraction osteotomy in ankylosing spondylitis

A long global thoracolumbar kyphosis is common in ankylosing spondylitis. Surgical correction of fixed sagittal malalignment by pedicle subtraction osteotomy (PSO) might improve disability and quality of life (QoL). Two-level osteotomies represent major procedures with a risk of hemorrhage. Combined open and minimal invasive surgery has not been described and might be considered. A 30-year-old female with ankylosing spondylitis was treated by golimumab and teriparatide. The treatment was stopped during pregnancy which led to vertebral compression fractures and kyphosis of 50° between T11 and L3. A PSO was planned at the kyphotic apex L2. The second PSO was planned at L4 according to the pelvic incidence of 56°, matching with a spinopelvic alignment Roussouly type 3. A derived full balance integrated method was used to calculate the amount of correction. During the first stage surgery, an open approach was performed from L1 to pelvis and combined with percutaneous cement-augmented instrumentation in already fused segments T5-T12, thus reducing perioperative morbidity. A stepwise approach including L2 PSO closure with temporary rods and L4 PSO with final instrumentation was used. Blood loss was estimated around 1100ml. The patient was able to walk on the second day after surgery. A secondary anterior fusion with LLI cages from L2 to L5 and an ALIF at L5-S1 were performed because of high non-ossified intervertebral disks to reduce the risk for nonunion and rod fractures. At 2-year follow-up, the patient's QoL had significantly improved and full spine radiographs showed stable normalized sagittal parameters. The combined open and percutaneous approach was feasible and might be considered as an alternative option to conventional open surgery when planning major deformity correction in ankylosing spondylitis.

Differences in lumbar segment angle among Roussouly types of global sagittal alignment in asymptomatic adult subjects.

A radiological study. To examine lumbar segment angle according to the Roussouly type of global sagittal alignment and to determine the reference disc angles in minimally invasive surgery (MIS) for adult spinal deformity. Optimal restoration of lumbar lordosis (LL) in adult spinal deformity surgery includes achieving the ideal shape of LL as well as the amount of LL. However, the distribution of lumbar segment angles by the Roussouly type has yet to be elucidated. Forty sets of whole spine lateral radiographs covering the four Roussouly types (N = 160) were obtained from a database of asymptomatic adult subjects. Global and spinopelvic parameters were measured. Disc and vertebral angles at each lumbar level were compared among the Roussouly types. There were 75 (46.9%) men with a mean age of 32.8 ± 8.9years among the total of 160 study subjects. A significant difference was found in spino-sacral angle, sacral slope, pelvic incidence, LL, and lower arc of LL (L4S1) among the Roussouly types (all P < 0.001). The ratio of the lower arc of LL (L4S1) to LL was 83.4% in Roussouly type 1, 65.2% in type 2, 64.7% in type 3, and 61.5% in type 4. The disc angles at the L1-2 and L2-3 levels in Roussouly type 1 were significantly smaller than in the other types. The disc angle at the L5-S1 level in Roussouly type 1 was significantly larger than that in type 2. Roussouly type 4 had a larger disc angle at the L2-3 and L4-5 levels than types 1 and 2. The results of this study showed that the disc angle distribution differs among Roussouly types. The configuration of LL as well as the amount of LL should be considered in adult spinal deformity surgery. Level IV.

Evaluation of a new sagittal classification system in adolescent idiopathic scoliosis.

The purpose of the present study was to validate a new spinal sagittal classification. We retrospectively included 105 consecutive AIS patients who underwent posterior spinal fusion. Preoperative long-standing EOS radiographs were available on all patients. Patients were classified according to the four suggested sagittal patterns: type 1, 2a, 2b or 3. Several predetermined sagittal parameters were compared between the groups. The mean preoperative Cobb angle was 64° ± 12°, and 73% of the patients were female. Of 105 patients, 51 were type 1, 14 were type 2a, one was type 2b and 39 were type 3. The distribution of the four sagittal patterns was significantly different compared with the original publication (p < 0.05). However, the two study populations were comparable in terms of Lenke and Roussouly types (p = 0.49 and 0.47, respectively). In our study population, the sagittal groups differed significantly in terms of thoracic kyphosis, length of thoracic and lumbar curves, lumbar lordosis, thoracic slope, C7 slope, pelvic incidence and sacral slope (p < 0.05). The distribution of the four sagittal patterns varies between AIS cohorts. Type 2b was rare, which limits the clinical applicability. Contrary to the original publication, we found that the spinopelvic parameters lumbar lordosis, pelvic incidence and sacral slope were significantly different between the Abelin-Genevois types. Hence, the corrective surgical strategy may need to incorporate these spinopelvic parameters to achieve a balanced spine requiring a minimum of energy expenditure. These slides can be retrieved under Electronic Supplementary Material.

224. Does Roussouly type affect revision surgery rates for proximal junctional kyphosis (PJK) and adjacent segment degeneration (ASD) after fusion for adult scoliosis?

BACKGROUND CONTEXT As spine types have been classified into 4 Roussouly types based upon their sacral slope and shape, it is unclear if certain types lead to higher or lower rates of adjacent segment breakdown after spinal fusion for scoliosis. PURPOSE There are certain Roussouly types that may predispose patients to a higher rate of proximal segment breakdown compared to others. STUDY DESIGN/SETTING Retrospective review of a single center North American spine center scoliosis cases from 2004 to 2016. PATIENT SAMPLE A total of 193 patients with minimum 2-year follow up were included. Mean follow up was 45 months. OUTCOME MEASURES PJK and ASD can occur after fusion for adult scoliosis. It is unclear if one Roussouly type predisposes or protects against proximal segment breakdown. We wished to investigate if certain Roussouly types were associated with higher or lower rates of adjacent segment breakdown. METHODS Retrospective review at a single North American spine center scoliosis cases. Radiographs were reviewed, and all cases were classified by Roussouly type (1 to 4) based upon preoperative 3-foot standing lateral radiographs. Records were reviewed for revision surgery proximal to the construct only, for either ASD or PJK, and patients were excluded if surgery was performed for infection, wound problems, implant failure, or surgery at the original index levels. Fusion types were classified as short ( RESULTS Patients were classified as type 1: 48, type 2: 66, type 3: 56, and type 4: 23. When evaluated by Roussouly type, there was no difference in revision surgery rates for ASD or PJK. However, when evaluating only type 2 spines, short fusion had a revision surgery rate of 35.1% (13/37) compared to 13.8% (7/29) for long fusions (p=0.0491). With regards to the entire cohort of 193 patients, short segment fusions had a revision surgery rate at the proximal level of 33.6% (36/107) compared to a long fusion rate of 16.3% (14/86), p=0.0014. CONCLUSIONS Short segment fusions had a statistically higher rate of surgery for proximal pathology for all spine types, and Roussouly type 2 spines had a higher rate of proximal pathology surgery with short fusions compared to long fusions. We could not detect a difference of revision surgery rates for proximal pathology for adult scoliosis based solely upon Roussouly type. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P102. Does matching Roussouly spinal shape and improvement in SRS-Schwab modifier contribute to improved patient-reported outcomes?

BACKGROUND CONTEXT The Roussouly Classification system of sagittal spinal shape and the SRS-Schwab adult spinal deformity (ASD) classification system have become important indicators of spine deformity. No prior studies have examined the outcomes of matching both Roussouly type and improving in Schwab modifiers postoperatively. PURPOSE Evaluate outcomes of matching Roussouly Type and improving in Schwab modifier following ASD surgery. STUDY DESIGN/SETTING Retrospective review of single-center ASD database. PATIENT SAMPLE A total of 103 ASD patients. OUTCOME MEASURES Roussouly types, Schwab modifiers, Health Related Quality of Life scores(HRQLs): Minimal Clinical Important Difference for ODI, EQ5D, VAS Leg B Type 2: PI 60°); (2) “current” Roussouly type (1: SS 45°), as previously published. One year (1Y) matched Roussouly: preoperative mismatched (Between ‘actual’ and ‘theoretical’ patients that matched at 1Y. Schwab modifiers at BL were identified: non-, moderate and severe deformity (0, +, ++) for PT, SVA, and PI-LL. Schwab improvement was defined as a decrease in a modifier at one year. RESULTS A total of 103 ASD patients (61.8yrs, 63.1%F, 30kg/m2). By surgical approach, 79.6% posterior, 10.7% combined, 2.9% anterior). Average levels fused: 4.6. BL breakdown of ‘current; Roussouly type: 28% Type 1, 25.3% Type 2, 32.0% Type 3, 14.7% Type 4. BL Roussouly mismatch: 65.3%. Breakdown BL Schwab modifiers: PT (0: 8.7%, +: 41.7%, ++: 49.5%), SVA (0: 29.7%, +: 20.3%, ++: 50%), PI-LL mismatch (0: 28.2%, +: 25.2%, ++: 46.6%). At one year, 19.2% of patients matched Roussouly target type, while according to Schwab modifiers, 12.6% improved in SVA, 42.7% in PI-LL, and 45.6% in PT. Patients who both met Roussouly type and improved in a Schwab by the modifiers: 9 PT (8.7%), 8 PI-LL (7.8%), 2 SVA (1.9%). There were 2 patients (1.9%) who met their Roussouly type and improved in all 3 Schwab modifiers. One year (1Y) matched Roussouly patients improved more in HRQLs (MCID for ODI, EQ5D, VAS Leg/Back Pain), when compared to mismatched Roussouly, but was not significant(P>0.05). Match Roussouly and improvement in PT Schwab met MCID for EQ5D significantly more (33.3% vs 10.6%, p=0.050). Matched Roussouly and PI-LL Schwab had more patients meet MCID for all HRQLs, yet none were significant, p>0.05. Matched Roussouly and improvement in SVA Schwab met MCID for ODI significantly more (p=0.024). CONCLUSIONS Patients who both matched Roussouly sagittal spinal type and improved in SRS-Schwab modifiers had superior patient-reported outcomes at 1-year. Utilizing both classification systems in surgical decision making can optimize postop patient outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

210. Comparing and contrasting the clinical utility of sagittal spine alignment classification frameworks: Roussouly vs SRS-Schwab

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, incorporating restoration of appropriate Roussouly Classificaion shape into surgical planning may improve outcomes. With the introduction and use of the SRS-Schwab ASD classification system, it is important to compare the utility of both classification frameworks as they relate to surgical outcomes. PURPOSE Compare outcomes of surgical ASD patients classified by both Roussouly and Schwab systems. STUDY DESIGN/SETTING Retrospective review of prospective ASD database. PATIENT SAMPLE A total of 515 ASD patients. OUTCOME MEASURES Complications; Health-related quality of life (HRQL): ODI, SF-36 PCS, SRS-22r. METHODS ASD patients with pre- and 2-year postop (2Y) radiographic/HRQL data were grouped by “theoretical” Roussouly type (Type 1: PI 60°) and “current” Roussouly type (1: SS 45°), as published. Means comparison tests assessed outcomes of those that mismatched “theoretical” and “current” types at both pre- and 2Y intervals (mismatched) to those of preoperative mismatched patients that matched at 2-years (matched). Subanalysis assessed outcomes of patients that improved in Schwab modifiers, and patients that both improved in both Schwab modifiers and matched Roussouly type by 2Y. RESULTS Included 515 ASD patients (59±14yrs, 80%F). The overall cohort showed moderate preoperative global and lumbo-pelvic deformity: SVA(64mm±73), PT(25°±11), PI-LL(16°±21). Preoperative breakdown of “current” Roussouly types: Type 1 (10%), Type 2 (54%), Type 3 (24%), Type 4 (12%). Preoperative mismatch between “current” and “theoretical” types was 60%. By 2Y, 16% of patients matched Roussouly types. Matched and Mismatched groups did not differ in rates of reaching MCID for any HRQL metrics by 2Y(all p>0.1). Reop, PJK and complications did not differ between matched and mismatched(all p>0.1), though mismatched patients showed a trend of increased instrumentation failure(17% vs 26%, p=0.080). By 2Y, 28% of patients improved in PT Schwab modifier, 37% in SVA, and 46% in PI-LL. Patients that improved in PT modifier had lower instrumentation failure rates (16% vs 24%) and higher rates of reaching 2Y MCID for ODI (58% vs 48%) and SRS Activity (75% vs 64%) than patients that did not improve. Patients that both Matched Roussouly at 2Y and improved in all Schwab modifiers met MCID for ODI and SRS Activity at higher rates than patients that did not. Roussouly Match patients that improved in Schwab PT met SRS Activity MCID at a higher rate, and had less renal, infection, and neurologic complications than patients that did not. Roussouly Match patients that improved in Schwab SVA also had superior SF-36 scores and fewer cardiopulmonary complications(all p CONCLUSIONS For surgical ASD patients, isolated restoration of sagittal spinal shape per the Roussouly system was not associated with superior clinical outcomes or complications by 2 years. In contrast, improvement in PT, per the SRS-Schwab system, was associated with substantial improvement in low-back disability by 2 years. Collectively, patients that both matched Roussouly sagittal type and improved in Schwab modifiers had superior complication and patient-reported outcomes by 2 years. These results suggest that concurrent consideration of both existing systems may offer utility in establishing optimal realignment targets. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

209. Global spinal deformity from the upper cervical perspective: what is “abnormal” in the upper cervical spine?

BACKGROUND CONTEXT Reciprocal changes in cervical alignment occur with incremental degrees of adult spinal deformity (ASD) severity, or across different sagittal morphotypes as described respectively by Schwab and Roussouly systems. The extent to which these systems relate changes in the upper cervical spine remains underexplored. PURPOSE To investigate quantitative anatomical relationships with regards to abnormal alignment in the upper cervical spine. STUDY DESIGN/SETTING Retrospective review of a prospective multicenter ASD database. PATIENT SAMPLE A total of 343 patients who met criteria for ASD. OUTCOME MEASURES Cervical alignment parameters (C2-C7 angle, C2 slope, McGregor's Slope, CBVA when available, segmental tilt), Ostrow Disability Index (ODI) METHODS Patients >18 years with ASD (scoliosis≥20°, SVA≥5cm, PT≥25°, or thoracic kyphosis ≥60°) and complete radiographic data at baseline (BL) & 1-year (1Y) were identified. Patients were grouped by BL PI and apex of LL into component types of the Roussouly classification system (Type 1: PI 65°). Patients were categorized by increasing severity of SRS-Schwab modifiers at BL (0, +, ++) and further grouped by anatomical malalignment, moving cranially (P: pelvic only; LP: lumbopelvic; TL: thoracolumbopelvic; C: subaxial & thoracolumbo-pelvic). Analysis of variance (ANOVA) tests assessed differences in BL upper cervical alignment parameters (C0-C2, C0 slope, McGregor's slope, CBVA) and ODI scores across Roussouly and Schwab modifier groups. RESULTS A total of 343 ASD patients were analyzed. Schwab modifiers at BL were as follows: SVA (0: 45.8%, +: 20.3%, ++: 33.9%), PI-LL (0: 42.3%, +: 20.7%, ++: 37.0%), PT (0: 38.6%, +: 36.2%, ++: 25.3%). By Roussouly classification, 4.2% were Type 1, 19.3% were Type 2, 43.1% were Type 3, and 33.3% were Type 4. Moving cranially up the spine, Group P (10.6%), Group LP (54.7%) and Group TL (8.5%) did not differ in C0-C2 angle, C0 slope, MGS or CBVA (all P>0.05). Group C (26.2%) had a significantly smaller C0-C2 angle, and more negative MGS, C0 slope, and CBVA than non-cervical groups. By Roussouly type, Type 1 trended slightly higher CBVA and MGS than types 2-4 without statistical significance (all P>0.05). No differences in CL, C0-C2, or C0S were found between Types 1-4 (all P>0.05). McGregor's slope (r=-0.131, P=0.015), CBVA (r=-0.473, P 34mm predicted a 1 unit(°) decrease in MGS (OR: 0.970 [0.948 – 0.993], p=0.010), while cSVA>51mm predicted a 1 unit increase in MGS (OR: 1.25[1.12-1.38], p CONCLUSIONS Our present study suggests that upper cervical alignment remains relatively stable through most broad variations of adult thoracolumbar deformity. Changes in SVA correlated most with upper cervical changes compared to other TL modifiers. Incremental trends in upper cervical alignment changes were observed as TL deformity extended cranially, with greatest variation in pts who also had subaxial malalignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Total disc replacement for lumbar degenerative disc disease: single centre 20years experience.

To report clinical and radiographic outcomes, rate of complications and influence on spinal alignment on long-term follow-up (FU) of patients who underwent lumbar total disc arthroplasty (TDR), bringing some evidence to determine the profile of the most well-suited patients for TDR. A retrospective review of patients underwent TDR for low back pain from degenerative disc disease (DDD) resistant to conservative treatment was performed. Demographic features, surgical data, clinical and radiographic outcomes, complications and spinopelvic parameters were evaluated. Thirty patients (32 TDR) were included with a mean FU of 164 ± 36.5months. The clinical outcomes measured by visual analogue scale and Oswestry Disability Index showed a significant improvement between preoperative and 1-year FU (p < 0.01). No significant temporal variance has been identified between 1-year and long-term follow-up (p > 0.05). The surgical revision rate was 10%. The overall rate of complications was 20%. At final follow-up, the mobility of the prosthesis was preserved in 68.75% of the cases, and 73.3% of the patients were globally well aligned. The optimal surgical indication is crucial to achieve excellent clinical and radiological outcomes. According to the literature and to our experience, we underline the importance of a coronal deformity < 15° Cobb angle and a Roussouly type 1 or 2 as the profile of the most well-suited patient for TDR. Our long-term results confirm the existing evidence about efficacy and safety of TDR as a reliable option, in optimal surgery indication, to treat DDD. These slides can be retrieved under Electronic Supplementary Material.