Axial Vertebral Rotation Research Articles

Radiographic Axial Malalignment is Associated With Pretreatment Patient-Reported Health-Related Quality of Life Measures in Adult Degenerative Scoliosis: Implementation of a Novel Radiographic Software Tool

Study DesignRetrospective study of prospectively collected data. ObjectivesThe purpose of this study was to evaluate the relationship between apical vertebral axial rotation and pretreatment patient-reported health-related quality of life (HRQOL), disability, and pain in patients with adult degenerative scoliosis (ADS) using a novel radiographic software tool. Summary of Background DataRecent studies have demonstrated that in ADS, sagittal and coronal plane deformity are weakly to moderately associated with HRQOL, disability, and pain. However, as ADS is a three-dimensional spinal deformity, the impact of axial malalignment on HRQOL is yet to be determined. MethodsA total of 74 ADS patients were enrolled. HRQOL measures included the Short Form-36v2 (SF-36v2) and Scoliosis Research Society questionnaire (SRS-22r). Disability and pain measures included the Oswestry Disability Index (ODI) and numeric rating scale back and leg pain. Radiographic measures included Cobb angle (CA), sagittal spinopelvic parameters, lateral and anteroposterior (AP) translation of the apical vertebra. The amount of apical vertebral axial rotation was measured on digital AP radiograph images using a novel software technology. Subjects were stratified into four clinical groups based on the degree of apical vertebral axial rotation. ResultsApical vertebral axial rotation showed no association with lateral (r = 0.21; p = .15) and AP (r = 0.08, p = .80) translation of the apical vertebra. A significant moderate association was found between apical vertebral axial rotation and Cobb angle (r = 0.57; p < .05). Patients in the group with the highest degree of apical vertebral axial rotation reported significantly worse ODI and SRS-22r Subtotal and Pain scores (p < .05), irrespective of sagittal spinopelvic parameters. ConclusionsThis is the first study that reports on the association between apical vertebral axial rotation and pretreatment HRQOL, disability, and pain in ADS. This study suggests that increased apical vertebral axial rotation is associated with suboptimal pretreatment health status scores. Level of EvidenceLevel III.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P29. Does the true AP radiograph for scoliosis differ from ancient convention? Lessons from 3D imaging

BACKGROUND CONTEXT Scoliosis is a three-dimensional deformity. As such, the rotational component must be considered during its evaluation and management. However, the severity of scoliosis has long been measured in the 2D coronal plane using the Cobb angle – a modality unable to account for axial vertebral rotation (VR). In the past, the Stagnara lateral radiograph has attempted to compensate for VR. To date, no similar radiographic view has been described for the AP plane. Recent advances in 3D CT imaging may allow clinicians to more accurately measure Cobb angles in scoliosis by compensating for axial VR. Here, we present a retrospective study comparing Cobb angle measurements taken from both traditional 2D radiographs, and rotationally compensated CT images. PURPOSE The purpose of this study is to compare Cobb angle measurements routinely made for AIS in both rotationally compensated and standard imaging. STUDY DESIGN/SETTING Retrospective matched cohort study. PATIENT SAMPLE A total of 66 patients diagnosed with AIS. OUTCOME MEASURES PT, MT, and TL/L curve Cobb angle values, coronal balance, thoracic and lumbar apical vertebral translation (T/L-AVT), thoracic and lumbar apical vertebral rotation (T/L-AVR), thoracic kyphosis, and sagittal balance. METHODS In this retrospective study, standard AP, lateral, and bending radiographs of 66 patients age 10-19 with AIS were obtained. Using multiplanar 3D CT, the coronal plane was reconstructed within the plane of the vertebral axis to form a rotationally compensated 3D CT image (RC-3DCT). The following measurements were made on both imaging modalities: PT, MT, TL/L curve, coronal balance, T/L-AVT, T/L-AVR, thoracic kyphosis, and sagittal balance. RESULTS Mean MT curve was found to be 40.56° on AP radiograph versus 35.39° on RC-3DCT (n=63, P=.00039). In 28 patients (42.4%), rotational compensation altered the end vertebra of the major curve by at least 1 level. The mean TL curve obtained on radiograph, was significantly larger than that of RC-3DCT (n=62; 35.34° vs. 30.98° ; P=.0046). AP films overstated coronal balance by over 50% when compared to RC-3DCT Mean T-AVT was measured to be 25.28 mm on conventional films and 19.46 mm on RC-3DCT (n=62; P=.00033). RC-3DCT L-AVT was significantly smaller than that of standard films (P=.0094). Mean T-AVT on standing film was 26.2±31.0°. The mean proximal thoracic kyphosis did not differ between the two modalities: 20.66° on radiograph versus 21.062° on RC-3DCT (P=.41). CONCLUSIONS Measurements traditionally made on AP radiograph to evaluate scoliosis may be inaccurate due to VR. Our data suggest that axial rotation of a patient 19° per Nash–Moe grade with respect to the coronal plane may adequately compensate for the rotational component of deformity without the need for CT. Additionally, rotational compensation may yield end vertebrae levels different from those obtained traditionally. In 42% of patients, VR compensation altered end vertebral designation by at least 1 level.

Radiographic methods to estimate surgical outcomes based on spinal flexibility assessment in patients who have adolescent idiopathic scoliosis: A systematic review.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity recognized with lateral curvature of the spine as well as axial vertebral rotation. Surgical interventions are recommended when patients with AIS have severe curvature (Cobb angle >45o). Spinal flexibility is one of important parameters for surgeons to plan surgical treatment. Few radiographic methods have been developed to assess spinal flexibility. A systematic review was performed to evaluate which preoperative radiographic methods should be used to estimate spinal flexibility based on the postoperative outcomes. Studies which included any of the five radiographic methods: (1) supine side-bending (SBR), (2) fulcrum-bending (FBR), (3) traction, (4) push-prone, and (5) suspension were reviewed and compared to determine which method provided the most accurate estimation of the postoperative outcomes. Seven case series, one case control, and multiple cohort studies reported the flexibility assessment methods with the estimations of postoperative outcomes on patients with AIS. The flexibility index defined as a correction rate relative to flexibility rate was used to estimate the immediate and final follow-up postoperative outcomes. Seven databases searched included MEDLINE, CENTRAL, EMBASE, CINAHL, Web of Science, LILACS, and Google Scholar. Three independent reviewers were involved for abstracts and full-texts screening as well as data extraction. The Quality in Prognostic Studies quality appraisal tool was used to assess the risk of bias within the studies. Also, the GRADE system rate was used to assess the evidence level across the studies. Forty-six articles were included. The distribution of the five flexibility methods in these 46 studies were SBR 38/46 (83%), fulcrum bending radiograph (FBR) 16/46 (35%), traction radiograph 5/46 (11%), push-prone 1/46 (2%), and suspension 1/46 (2%). Based on the overall assessment of flexibility indices, FBR had the best estimation of postoperative correction among the five methods. FBR method provided the best estimations of immediate and final follow-up postoperative outcomes for moderate (25°-45°) and severe (>45°) curves, respectively. For main thoracic and thoracolumbar/lumbar curves, the best estimations were traction, and FBR. However, in the reviewed articles, the risk of bias was rated moderate and the quality of evidence was rated very low to low so that a strong conclusive statement cannot be made. SBR method was the most commonly used method to assess the spinal flexibility. The FBR method was the most accurate method to estimate the postoperative outcomes based on the limited evidence of the 46 articles.

Factors influencing spinal curvature measurements on ultrasound images for children with adolescent idiopathic scoliosis (AIS).

The measurements of spinal curvatures using the ultrasound (US) imaging method on children with scoliosis have been comparable with radiography. However, factors influencing the reliability and accuracy of US measurement have not been studied. The purpose of this study is to investigate the effects of curve features and patients’ demographics on US measurements and to determine which factors influence the reliability and accuracy. Two hundred children with scoliosis were recruited and scanned with US by one experienced operator and three trainees. One experienced rater measured the proxy Cobb angles from US images twice one week apart and compared the results with clinical radiographic records. The correlation and accuracy between the US and radiographic measurements were subdivided by different curve severities, curve types, subjects’ weight status and US acquisition experiences. A total of 326 and 313 curves were recognized from radiographs and US images, respectively. The mean Cobb angles of the 13 missing curves were 17.4±7.4° and 11 at the thoracic region. Among the 16 curves showing large discrepancy (≥6°) between US and radiographic measurements, 7 were main thoracic and 6 were lumbar curves. Twelve had axial vertebral rotation (AVR) greater than 8°. The US scans performed by the experienced operator showed fewer large discrepancy curves, smaller difference and higher correlation than the scans from the trainees (3%, 1.7±1.5°, 0.95 vs 6%, 2.4±1.8°, 0.90). Only 4% missing and 5% large discrepancy curves were demonstrated for US measurements in comparison to radiography. The missing curves were mainly caused by small severity and in the upper spinal region. There was a higher chance of the large discrepancy curves in the main thoracic and lumbar regions with AVR>8°. A skilled operator acquired better US images and led to more accurate measurements especially for those subjects with larger curvatures, AVR and body mass index (BMI).

The effects of rotation on radiological parameters in the spine.

Vertebral rotation in straight spines or in spines with small scoliosis may potentially affect measurement of radiological parameters in both the frontal and sagittal plane. This is important, since it could lead to potential misdiagnosis of scoliosis and other clinical consequences, and until now, this has not been examined. To examine the effect of axial vertebral rotation of the spine on measurement of common radiological parameters. Reconstructions from computed tomography scans of 40 consecutive included and anonymized patients with straight spines or small scoliosis. Fourteen sagittal and coronal reconstructions covering the whole pelvis and spine were executed. Radiographic parameters in both the frontal and sagittal plane were measured blinded and separately by three doctors. These parameters were evaluated for inter-rater reliability using intraclass correlation coefficient and mixed model analysis for the effects of rotation. The parameters were also analyzed sub-stratified according to "Lenke's classification" and 15 sub-categories of thoracic and lumbar Cobb's angle (CA). Vertebral rotation in general does not have any significant effects in both the frontal and sagittal plane. However, there are significant effects on CA and spinopelvic radiologic parameters in extreme rotation or for larger scoliosis. Inter-rater reliability was very good to good. In conclusion, axial spinal rotation does not influence common radiological parameters in the frontal and sagittal plane, except in cases of extreme rotation or large scoliosis for selected parameters; thus, this does not lead to potential misinterpretation in scoliosis diagnosis, treatment, or research.

Accuracy and Precision of Seven Radiography-Based Measurement Methods of Vertebral Axial Rotation in Adolescent Idiopathic Scoliosis

Study DesignAssessment of vertebral axial rotation measurement methods. ObjectivesTo assess the accuracy and precision of seven radiography-based vertebral axial rotation measurement methods for typical scoliotic deformity before and after posterior instrumentation. Summary of Background DataVertebral axial rotation is an important component to evaluate transverse plane scoliotic deformities. Several measurement methods were developed based on coronal plane radiographs or computerized 3D reconstruction. Their ability to accurately and precisely measure axial rotation, either pre- or postoperatively, is not well known. MethodsTwo synthetic vertebrae, with and without instrumentation, were fixed in a jig allowing 3D rotation manipulations. Fifty-three configurations of 3D rotations were radiographed. Two observers evaluated seven measurement methods: one visual estimation, two ruler-based (Nash-Moe and Perdriolle), one analytical (Stokes), and three 3D-reconstruction techniques (based on pedicles, based on eight vertebra landmarks, and a surface-based reconstruction software SterEOS). Measurements were repeated one week later. ResultsIntraobserver precision ranged from 2.0° (Perdriolle/SterEOS) to 3.6° (visual estimation) for the noninstrumented vertebra, and from 2.2° (SterEOS) to 9.7° (Nash-Moe) for the instrumented vertebra. Interobserver precision ranged from 1.2° (SterEOS) to 9.3° (Nash-Moe) for the noninstrumented vertebra, and from 1.7° (SterEOS) to 6.2° (Visual Estimation) for the instrumented vertebra. Accuracy of the methods ranged from 2.1° with SterEOS to 9.1° with Nash-Moe ruler. The measurement error was significantly associated with the level of axial rotation for Nash-Moe and 3D reconstruction techniques with low to moderate correlation. ConclusionsThe majority of radiography-based methods measured vertebral axial rotation with an average error of 2° to 5°. The Nash-Moe method should be avoided, considering its inaccuracy greater than 9°. The instrumentation did not compromise the precision or the accuracy of measurement. The measurement accuracy of 3D reconstruction methods was impaired by the severity of the axial rotation. Level of EvidenceN/A.

Differential Rod Contouring is Essential for Improving Vertebral Rotation in Patients With Adolescent Idiopathic Scoliosis: Thoracic Curves Assessed With Intraoperative CT.

A case series. We investigated the contributions of rod contouring and differential rod contouring (DRC) to the reduction of apical axial vertebral body rotation in patients with adolescent idiopathic scoliosis (AIS). DRC is used for posterior spinal correction and fusion. The contribution of DRC to vertebral body derotation is unclear. We analyzed the results of intraoperative computed tomography (CT) in 40 consecutive AIS patients with thoracic curves (Lenke type I or II, 35; type III or IV, 5). Rod contour before initial rod rotation was analyzed by x-ray. Periapical rod contour between concave and convex rod rotation (RR) were analyzed by cone-beam CT imaging. To analyze the reduction of vertebral body rotation with DRC, intraoperative cone-beam CT scans of the three apical vertebrae of the major curve of the scoliosis (120 vertebrae) were taken post-concave RR and post-convex DRC in all patients. The angle of vertebral body rotation was measured. In addition, the contribution of rod contouring to apical vertebral body derotation was analyzed. Rib hump indices (RHi) were measured by pre- and postoperative CT. The mean vertebral body rotation angles post-concave RR and post-convex DRC were 15.3° and 9.3°, respectively, for a mean reduction of vertebral rotation in convex DRC after concave RR of 6.0° for thoracic curves (P < 0.001). The RHi was significantly improved by DRC (P < 0.05). Improved apical vertebral rotation was significantly correlated with the difference of apical rod curvature between concave and convex. Vertebral derotation was significantly higher in curves with > 10° difference between concave and convex rod curvature than differences < 10°. DRC contributed substantially to axial derotation and reducing rib hump in thoracic scoliosis. The degree of apical rod curvature correlated with the degree of apical vertebral derotation. 4.

Reliability of Three-Dimensional Spinal Modeling of Patients With Idiopathic Scoliosis Using EOS System

Study DesignThree-dimensional (3D) spinal models of children with idiopathic scoliosis (IS) were created using the EOS imaging system (EOS) and sterEOS software. ObjectiveTo determine the inter- or intraobserver reproducibility of the 3D spinal models in children with IS of different apex locations. Summary of Background Data3D spinal model measurements include the Cobb angle, kyphosis, lordosis, and axial vertebral rotation (AVR). Variation of these measurements between two investigators and two different trials by the same investigator were analyzed by inter- and intraclass correlation coefficients (ICCs). MethodsBiplanar radiographic images of 15 patients (age: 6–15 years) with IS were uploaded into the sterEOS software. Spinal and pelvic markers were manually identified to construct a 3D spinal model and measure spinal parameters. Two trained examiners independently performed modeling and performed modeling in spaced out trials. The ICC between inter- and intraobservers were calculated. ResultsICCs between inter- and intraobservers were significant for all parameters (p < .05). Both the inter- and intraobservers showed excellent agreement for the Cobb angles in the thoracic segment, kyphosis and lordosis. Substantial interobserver agreement and excellent intraobserver agreement were determined for the Cobb angle in the thoracolumbar or lumbar (TL/L) segment, with less than 6° difference between two raters and less than 2° difference between two trials. Substantial interobserver agreement for the AVR in the TL/L region and substantial interobserver agreement for the AVR in the thoracic region were found, with less than 4° difference between raters. One rater had substantial intraobserver agreement for the AVR in the TL/L region whereas another rater reported moderate to substantial intraobserver agreement in both the thoracic and TL/L regions, with less than 3° difference between trials. ConclusionThe EOS system shows reliable and repeatable results in 3D spinal modeling of children with IS. Level of EvidenceLevel III.

Vertebral instability of lumbar spine and its neurological presentations

Background. &#x0D; The research results of data of 57 patients with vertebral instability of lumbar spine with neurological presentations are presented. Patients were on in-patient treatment at the Vertebral surgery department of Institute of Traumatology and Orthopedics (Kyiv) in 2010–2014. &#x0D; Research object. &#x0D; The aim of the research was to determine the features of clinical signs and X-ray measures depending on type and stage of instability in lumbar spine. &#x0D; Materials and methods. &#x0D; The research is based on the analysis of management of 57 patients with lumbar spine instability. The management consisted of anamnesis, examination of patients, X-ray of spine, MRI and CT. The majority of patients were males. There were 35 (61.4 %) males, 22 (38.6 %) females among all of the patients. Due to the data of the research it was inquired that the spine instability was detected frequently in the most employable age, from 20 to 44 years – 30 (52.6 %) cases. &#x0D; Results and discussion. &#x0D; The spine instability is clinical and radiographic manifestation of pathological removability of contiguous vertebras due to each other. This resulted in lesion of vertebras and adjoined vessels and nerves, caused by inadequate supporting system of spinal motion segments. Failure of spinal motion segments develops mainly in degenerative and dystrophic disorders resulted in acute or chronic congestions influenced by microtraumas. Development of secondary lesions of spine and spinal radixes are affected by deformation of spine and spinal channel. Emerging of pathological processes is accompanied by orthopedic and neurological presentations, that requiring surgical correction. &#x0D; Conclusions. &#x0D; Instability of VMS is caused by structure alteration of intervertebral discs, aquatics and processes joints and a part of vertebral arc between joints. Clinical signs depend on the level of localization and the stage of spine instability. Among patients with spine instability the manifestation of radixes lesions were on the 1st place – 29 (50.9 %) cases, on the 2nd place – lesions of lumbago – 19 (33.3 %) cases. X-ray features of instability are: enlargement of linear displacement of vertebral body in sagittal plane more than 4.5 mm, segmental axial rotation of vertebra – more than 40°.

Vertebral Axial Asymmetry in Adolescent Idiopathic Scoliosis

Study DesignRetrospective study. ObjectivesTo investigate parameters of axial vertebral deformation in patients with scoliosis compared to a control group, and to determine whether these parameters correlated with the severity of spine curvature, measured as the Cobb angle. Summary of Background DataAdolescent idiopathic scoliosis (AIS) is the most common type of spinal deformity. Many studies have investigated vertebral deformation, in terms of wedging and pedicle deformations, but few studies have investigated actual structural changes within vertebrae. MethodsThis study included 20 patients with AIS (Lenke 1–3, mean age: 15.6 years, range: 11–20). We compared preoperative low-dose computed tomography (CT) examinations of patients with AIS to those of a control group matched for age and sex. The control individuals had no spinal deformity, but they were admitted to the emergency department for trauma CTs. We measured the Cobb angles and the axial vertebral rotation (AVR), axial vertebral body asymmetry (AVBA), and frontal vertebral body rotation (FVBR) for the superior end, inferior end, and apical vertebrae, with in-house–developed software. Correlations between entities were investigated with the Pearson correlation test. ResultsThe average Cobb angles were 49.3° and 1.3° for the scoliotic and control groups, respectively. The patient and control groups showed significant differences in the AVRs of all three vertebra levels (p < .01), the AVBAs of the superior end and apical vertebrae (p < .008), and the FVBR of the apical vertebra (p = .011). Correlations were only found between the AVBA and FVBR in the superior end vertebra (r = 0.728, p < .001) and in the apical vertebra (r = 0.713, p < .001). ConclusionsCompared with controls, patients with scoliosis showed clear morphologic differences in the midaxial plane vertebrae. Differences in AVR, AVBA, and FVBR were most pronounced at the apical vertebra. The FVBR provided valuable additional information about the internal rotation and deformation of vertebrae. Level of EvidenceLevel III.

Performance comparison of feature-based and CSCPG models for 3D spine reconstruction

3D deformity of the spine-like scoliosis is commonly assessed using stereo-radiographic technique. The Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) modelling fail in this case, as they are obtained with the patient in sleeping position. Also, they are associated with heavy cost and radiation hazards. We have developed two models namely, feature-based model and a Combined Stereo-Corresponding Point And Geometric (CSCPG) model for 3D spine reconstruction using biplanar x-rays. The spinal disorder is quantified using two parameters, namely axial vertebral rotation and spinal curvature using both these methods. Their performance is compared by considering Non-Stereo-Corresponding Point (NSCP) model as the gold standard method. The feature-based model is less accurate compared to the CSCPG model. The performance of the feature-based model is also poor in the case of deformity quantification. A statistical significance test is conducted in order to verify its suitability in diagnosis of the spinal disorders. The accuracy of feature-based model can be improved by incorporating additional landmark features from the biplanar radiographs. The proposed CSCPG model has accuracy closer to the gold standard technique and can be used a diagnostic tool for the spinal disorders.

Anatomical Modifications during the Lateral Transpsoas Approach to the Lumbar Spine. The Impact of Vertebral Rotation.

We investigated impact of vertebral axial rotation on neurovascular anatomy in adult spinal deformity (ASD) patients and provided recommendations on the approach based on degree of axial rotation. In order to isolate vertebral rotation (VR) impact from the superimposed degenerative cascade observed in adulthood, adolescent idiopathic scoliosis (AIS) patients were analyzed. Magnetic resonance imaging (MRI) scans (L1-S1) from 50 right-convex thoracic (left-convex lumbar) AIS patients were analyzed. At each intervertebral level, VR, lumbar plexus depth (LPD), and vascular structure depth (VSD) were evaluated. Paired t test analyses were used to describe anatomic differences between the concave and convex aspect of our patients' curves. Correlation analysis was used to investigate relationships with soft tissue modifications and VR. Fifty AIS patients (17M, 33F) with mean thoracic Cobb of 50.6° ± 17.0° and mean lumbar Cobb of 41.9° ± 13.0° were included. Mean VR at each level was L1-2 = -6.6°, L2-3 = -7.7°, L3-4 = -6.5°, L4-5 = -4.7°, L5-S1 = -2.6° (negative value denotes clockwise rotation). We found significant differences (P < .05) between concave-convex (right-left) LPD at each level (L1-2 = 3.7 mm, L2-3 = 5.1 mm, L3-4 = 4.2 mm, L4-5 = 2.2 mm, L5-S1 = 2.2 mm). Vascular structure depth was significantly different at L1-L2 (3.2 mm) and L5-S1 (3 mm). Significant correlation was found between increasing VR and concave-convex LPD difference (r = 0.68, P < .001). This study demonstrates that displacement of the lumbar plexus is tied to the magnitude of VR in patients with AIS. When approaching the lumbar spine, this displacement widens the safe surgical corridor on the convex side and narrows the corridor on the concave side. IV. Preoperative review of MRI scans should occur to assess the patient's safe surgical corridor for lateral lumbar interbody fusion (LLIF). Adult spinal deformity surgeons who approach a degenerated spine in patients with progressive AIS in adulthood must carefully plan for patient positioning, neurovascular anatomy, and realignment objectives prior to the day of surgical intervention.

Tridimensional Analysis of Rotatory Subluxation and Sagittal Spinopelvic Alignment in the Setting of Adult Spinal Deformity

Study DesignRetrospective single-center. ObjectiveTo investigate rotatory subluxation (RS) in adult spinal deformity (ASD) with three-dimensional (3D) stereoradiographic images and analyze relationships between RS, transverse plane parameters, spinopelvic parameters, and clinical outcomes. BackgroundRecent research has demonstrated that sagittal plane malalignment and listhesis correlate with ASD patient-reported outcomes. However, there is still a lack of knowledge regarding the clinical impact of 3D evaluation and rotatory subluxation. Recent developments in stereoradiography allow clinicians to obtain full-body standing radiographs with low-dose radiation and 3D reconstruction. MethodsOne hundred thirty lumbar ASD patients underwent full-spine biplanar radiographs (EOS Imaging, Paris, France). Clinical outcomes were recorded. Using sterEOS software, spinopelvic parameters and lateral listhesis were measured. 3D transverse plane parameters included apical axial vertebral rotation, axial intervertebral rotation (AIR), and torsion index (sum of AIR in the curve). ASD patients were divided in three groups: AIR <5°, 5°< AIR <10°, AIR >10°. Groups were compared with respect to radiographic and clinical data. Correlations were performed between the transverse and sagittal plane parameters and clinical outcomes. ResultsPatients with AIR >10° were significantly older, with larger Cobb angle (39.5°) and greater sagittal plane deformity (pelvic incidence–lumbar lordosis mismatch 11.7° and pelvic tilt 22.6°). The AIR >10° group had significantly greater apical vertebra axial rotation apex (24.8°), torsion index (45°), and upper-level AIR (21.5°) than the two other groups. Overall, 27% of AIR patients did not have two-dimensional (2D) lateral listhesis. Patients with AIR >10° had significantly worse Oswestry Disability Index and more low back pain. ConclusionFor patients in which lateral listhesis was unreadable in 2D imaging, rotatory subluxation was revealed using stereoradiography and at an earlier disease stage. Moreover, different 3D transverse plane parameters are related to different patient-reported outcomes. Therefore, axial rotation can be considered in evaluation of lumbar degenerative scoliosis severity and prognosis. Level of EvidenceLevel III.

Evaluating the Change in Axial Vertebral Rotation Following Thoracoscopic Anterior Scoliosis Surgery Using Low-Dose Computed Tomography

Background ContextIn recent years, there has been increasing appreciation of the need to treat scoliosis as a three-dimensional deformity. PurposeAssessment of surgical strategies and outcomes should consider not only the coronal plane correction but also derotation of the transverse plane deformity that can affect trunk appearance. Study DesignThis study included a cohort of 29 female adolescent idiopathic scoliosis patients who received thoracoscopic single rod anterior fusion (TASF) surgery. This study used pre- and postoperative low-dose computed tomographic (CT) scans to accurately measure apical axial vertebral rotation (AVR). MethodsThe pre- and postoperative values for clinically measured coronal Cobb correction and rib hump correction as well as AVR were compared to determine whether these values improved postoperatively. There are no conflicts of interest to report for authors of this investigation. ResultsAs expected, statistically significant reductions in coronal Cobb angle (mean preoperative Cobb 51°, reducing to 24° at the two-year follow-up) and rib hump (mean preoperative rib hump 15°, reducing to 7° at two-year follow-up) were achieved. The mean reduction in apical AVR measured using CT was only 3° (mean preoperative AVR 16°, reducing to 13° at two-year follow-up), which was statistically but not clinically significant. Significant correlations were found between Cobb angle and rib hump, between Cobb angle and AVR, and between AVR and rib hump, suggesting that patients with greater coronal Cobb correction also achieve better derotation with this surgical procedure. ConclusionsThe historical low-dose CT data set permitted detailed three-dimensional assessment of the deformity correction that is achieved using thoracoscopic anterior spinal fusion for progressive adolescent idiopathic scoliosis.

The impact of direct vertebral rotation (DVR) on radiographic outcome in surgical correction of idiopathic scoliosis

IntroductionRecent developments of spinal instruments allow to address nearly all components of idiopathic scoliosis. Direct vertebral rotation (DVR) maneuver was introduced to correct apical axial vertebral rotation. It is however still not well established how efficiently DVR affects results of scoliosis correction. The object of the study was to evaluate en bloc apical vertebral rotation (DVR) and its impact on coronal and sagittal correction of the spine in patients undergoing surgical scoliosis treatment.Materials and methodsThirty-six consecutive patients who underwent posterior spinal fusion with pedicle screws only constructs for idiopathic scoliosis. Fifteen patients (20 curves) were corrected by rod derotation only and 21 patients (26 curves) had both rod derotation and DVR. Curve measurements were performed on x-rays obtained before and postoperatively—coronal curves, kyphosis (T2–T12, T5–T12). Spine flexibility was assessed on prone bending x-rays. Apical axial rotation was determined on CT scans obtained intraoperatively and postoperatively. Rotation angle (RAsag) was measured according to Aaro and Dahlborn.ResultsWe observed reduction of RAsag in all patients; however, in DVR group, decrease was greater, by 31.8% comparing to non-DVR group, by 8.6% (p = 0.0003). Mean coronal correction in DVR group was 68.8% and in rod derotation group without DVR 55% (p = 0.002). No significant correlation was found between degree of derotation obtained and coronal correction. In DVR group T2–T12 kyphosis has increased in 28 (65%) patients whereas in non-DVR group in 31 (69%) cases. Mean value of T2–T12 kyphosis growth was 16.7% in DVR and 22.1% in non-DVR group. These differences however did not occur statistically significant.ConclusionsDirect vertebral rotation (DVR) maneuver reduces significantly apical rotation of the spine, enhances ability of coronal correction, and it does not reduce thoracic kyphosis.

3D-modeling of the spine using EOS imaging system: Inter-reader reproducibility and reliability.

ObjectivesTo retrospectively assess the interreader reproducibility and reliability of EOS 3D full spine reconstructions in patients with adolescent idiopathic scoliosis (AIS).Methods73 patients with mean age of 17 years and a moderate AIS (median Cobb Angle 18.2°) obtained low-dose standing biplanar radiographs with EOS. Two independent readers performed “full spine” 3D reconstructions of the spine with the “full-spine” method adjusting the bone contour of every thoracic and lumbar vertebra (Th1-L5). Interreader reproducibility was assessed regarding rotation of every single vertebra in the coronal (i.e. frontal), sagittal (i.e. lateral), and axial plane, T1/T12 kyphosis, T4/T12 kyphosis, L1/L5 lordosis, L1/S1 lordosis and pelvic parameters. Radiation exposure, scan-time and 3D reconstruction time were recorded.ResultsInterclass correlation (ICC) ranged between 0.83 and 0.98 for frontal vertebral rotation, between 0.94 and 0.99 for lateral vertebral rotation and between 0.51 and 0.88 for axial vertebral rotation. ICC was 0.92 for T1/T12 kyphosis, 0.95 for T4/T12 kyphosis, 0.90 for L1/L5 lordosis, 0.85 for L1/S1 lordosis, 0.97 for pelvic incidence, 0.96 for sacral slope, 0.98 for sagittal pelvic tilt and 0.94 for lateral pelvic tilt. The mean time for reconstruction was 14.9 minutes (reader 1: 14.6 minutes, reader 2: 15.2 minutes, p<0.0001). The mean total absorbed dose was 593.4μGy ±212.3 per patient.ConclusionEOS “full spine” 3D angle measurement of vertebral rotation proved to be reliable and was performed in an acceptable reconstruction time. Interreader reproducibility of axial rotation was limited to some degree in the upper and middle thoracic spine due the obtuse angulation of the pedicles and the processi spinosi in the frontal view somewhat complicating their delineation.

The Impact of Direct Vertebral Rotation (DVR) on Radiographic Outcome in Surgical Correction of Idiopathic Scoliosis

Introduction: Recent developments of spinal instruments allow to address nearly all components of idiopathic scoliosis. Direct vertebral rotation (DVR) maneuver was introduced to correct apical axial vertebral rotation. It is however still not well established how efficiently DVR affects results of scoliosis correction. The object of the study was to evaluate en bloc apical vertebral rotation (DVR) and its impact on coronal and sagittal correction of the spine in patients undergoing surgical scoliosis treatment. Material and methods: 36 consecutive patients who underwent posterior fusion with pedicle screws only constructs for idiopathic scoliosis. 15 patients (20 curves) were corrected by rod derotation only and 21 patients (26 curves) had both rod derotation and DVR. Curve measurements were performed on x-rays obtained before and post operatively - coronal curves, kyphosis (T2-T12, T5-T12). Spine flexibility was assessed on prone bending x-rays. Apical axial rotation was determined on CT scans obtained intraoperatively and postoperatively. Rotation angle (RAsag) was measured according to Aaro and Dahlborn. Results: We observed reduction of RAsag in all patients, however in DVR group decrease was greater, by 31.8% comparing to non-DVR group, by 8.6% (p=0.0003). Mean coronal correction in DVR group was 68.8% and in rod derotation group without DVR 55% (p=0.002). No significant correlation was found between degree of derotation obtained and coronal correction. In DVR group T2-T12 kyphosis has increased in 28 (65%) patients whereas in non DVR group in 31 (69%) cases. Mean value of T2-T12 kyphosis growth was 16.7% in DVR and 22.1% in non DVR group. These differences however did not occur statistically significant. Conclusions: Direct vertebral rotation (DVR) manoeuvre reduces significantly apical rotation of the spine, enhances ability of coronal correction and it does not reduce thoracic kyphosis.

Three-dimensional reconstruction using stereoradiography for evaluating adult spinal deformity: a reproducibility study.

In addition to the sagittal alignment, impact of transverse plane parameters (TPP) and rotatory subluxation on patients reported outcomes were highlighted. One of the hypotheses for genesis of degenerative scoliosis is disc degeneration with increased axial vertebral (AVR) and intervertebral rotation (AIR). Therefore, TPP analysis at early stage of the scoliosis seems of particular interest. This study aims at assessing reliability of tridimensional (3D) reconstructions of adult spinal deformity (ASD) patients. Thirty ASD patients underwent biplanar radiographs and were divided into two groups (Cobb angle >30° or <30°). Spinal parameters and TPP (apical AVR, AIR of upper and lower level of main curve) were measured. Four operators performed 3D reconstructions twice. Intra and inter-observer reliabilities were analyzed using ISO standard 5725-2, to quantify the global standard deviation of reproducibility (S R). Mean Cobb angle was 31°, mean age 55years (70% of female). Mean values of apical AVR, upper and lower level AIR were, respectively, 16°±15°, 6°±6° and 5°±5°. Spinopelvic parameters S R were below 4.5°. For Cobb angle <30°, S R was 7.8°, 9.6°, 4.5° and 4.9°, respectively, for AVR apex, torsion index, upper and lower AIR. Reliability was worse in the group of patients with Cobb angle above 30°. 3D analysis was reliable for Cobb and sagittal parameters. 3D analysis for TPP was reproducible when Cobb is below 30°. However, uncertainty is larger for Cobb above 30°. Nevertheless, 3D reconstructions could help surgeons to anticipate onset of rotatory subluxation while assessing axial rotation evolution for small deformity and choose best delay for surgical treatment.

Quantification of spinal deformities using combined SCP and geometric 3D reconstruction

Abstract Three dimensional reconstruction is essential in accurate diagnosis of numerous spinal deformities which are 3D in nature. The stereo-radiographic reconstruction involving bi-planar X-rays is one of the most commonly used methods. Algorithms with stereo-corresponding point (SCP) or non-stereo-corresponding point (NSCP) can be used to achieve this 3D reconstruction. But, the NSCP method is slower and needs manual identification of many anatomical landmarks. Hence it suffers from observer variability and has restricted usage in normal clinical setup. Thus, a hybrid method is proposed in which the SCP reconstructed model is refined using the geometric features from the X-rays to achieve the accuracy closest to NSCP method. The SCP model is constructed using the X-rays on a calibration bench from the scoliotic subject. From these X-rays the vertebral features are extracted automatically. The SCP model structure is refined using the geometric transformations according to the extracted features. The 3D model thus formed is called combined SCP and geometric (CSCPG) reconstruction. By considering the NSCP model as a reference, both qualitative and quantitative approaches are followed to validate the proposed model. The CSCPG method has lesser observer variability as it needs only six anatomical landmarks per vertebra. Further, it is faster and the reconstruction error is within the acceptable limits. To quantify the deformities like axial vertebral rotation and spinal curvature novel methods have been proposed. The axial vertebral rotation is measured using simple vertebra vector parametric computations. It needs identification of only two landmarks per vertebra for angle measurement. The apical vertebra gives the plane of maximum curvature. The actual spinal curvature has to be computed on this plane. A semi-automatic method is proposed to compute this curvature using a new projection technique. The deformity quantification methods are validated using manual measurements as well as the results from standard approaches. Hence, a fast, simple and economic 3D diagnostic method is developed for quantification of the spinal deformities.

A Novel Approach for Spinal Deformity Quantification Using Stereo-Radiographic 3D Reconstruction

The 3D reconstruction of the human spine is essential for accurate diagnosis of deformities like scoliosis. Here, a low cost stereo-radiographic 3D reconstruction method is proposed. A generic model is built using biomedical modeling of a cadaveric spine. Biplanar radiographs are obtained from the subject using a calibration apparatus. Six stereo-corresponding and nineteen non stereo-corresponding points per vertebra are identified and their 3D positions are computed. Using these landmarks, the generic model is deformed to obtain a personalized spine model using dual kriging algorithm. A novel technique is proposed for evaluating spinal deformities like axial vertebral rotation and spinal curvature. First, the axial vertebral rotation is found using vertebra vector parametric calculations. Proposed semi-automated method needs identification of only two landmarks per vertebra. The most tilted vertebra is used to find the plane in which spinal curvature is maximized. At this plane, the spinal curvature is automatically computed using a projection technique. The 3D spine reconstruction thus obtained is validated by back projecting it on both the x-rays. A close match among the projected and real vertebral contours are observed. Also, a quantitative validation of 3D reconstruction and deformity quantification techniques have been presented. Thus, a low cost 3D diagnostic procedure is developed for spinal deformity quantification