Measurement Of Vertebral Rotation Research Articles

Using machine learning to automatically measure axial vertebral rotation on radiographs in adolescents with idiopathic scoliosis.

Adolescent idiopathic scoliosis is a 3D lateral spinal curvature coupled with axial vertebral rotation (AVR). Measuring AVR during clinic is important because it affects treatment options and predicts the risk of scoliosis progression. However, manual measurements are time consuming and have high inter-rater and intra-rater errors. This study aimed to develop a machine learning algorithm based on convolutional neural networks (CNNs) to automatically calculate AVR on posteroanterior radiographs using three different segmentations including spinal column, individual vertebra, and pedicles. Separate labeling and training processes were performed on each of the developed segmentation algorithms. The final machine learning software was tested on 221 vertebrae from 17 spinal radiographs. An experienced rater with over 25 years of experience measured the 221 vertebral rotations manually. By comparing the manual and the fully automatic measurements, 81% (178/221) of the automatic measurements were within the clinical acceptance error (±5°). The mean absolute difference and the standard deviation between the manual and automatic measurements was 4.3°±5.7°. Based on the Bland-Altman plot, the manual and automatic measurements had a strong correlation and no bias. The error did not relate to the severity of the rotation. This method is fully automatic, and the result is comparable to others.

Validity and Absolute Reliability of Axial Vertebral Rotation Measurements in Thoracic and Lumbar Vertebrae

Axial vertebral rotation (AVR) and Cobb angles are the essential parameters to analyse different types of scoliosis, including adolescent idiopathic scoliosis. The literature shows significant discrepancies in the validity and reliability of AVR measurements taken in radiographic examinations, according to the type of vertebra. This study’s scope evaluated the validity and absolute reliability of thoracic and lumbar vertebrae AVR measurements, using a validated software based on Raimondi’s method in digital X-rays that allowed measurement with minor error when compared with other traditional, manual methods. Twelve independent evaluators measured AVR on the 74 most rotated vertebrae in 42 X-rays with the software on three separate occasions, with one-month intervals. We have obtained a gold standard for the AVR of vertebrae. The validity and reliability of the measurements of the thoracic and lumbar vertebrae were studied separately. Measurements that were performed on lumbar vertebrae were shown to be 3.6 times more valid than those performed on thoracic, and with almost an equal reliability (1.38° ± 1.88° compared to −0.38° ± 1.83°). We can conclude that AVR measurements of the thoracic vertebrae show a more significant Mean Bias Error and a very similar reliability than those of the lumbar vertebrae.

30. Retrospective comparative analysis of combined vs only posterior approach for treating severe scoliosis

BACKGROUND CONTEXT Studies comparing two-stage approach (first anterior then posterior) and only posterior approach for treating scoliosis are rather scarce, with shorter follow-up and lack of clinical data. PURPOSE The purpose of the retrospective study was to compare long-term clinical and radiological outcomes in comparable groups of patients when using different surgical approaches (two-stage and only posterior) for idiopathic scoliosis operations. STUDY DESIGN/SETTING A retrospective, one center, institutional review board approved study. PATIENT SAMPLE A total of 348 patients with idiopathic scoliosis were operated on using CD hybrid instrumentation with pedicle screw and hooks. Only patients with curvatures ≥61 ° were analyzed and divided in two groups: two-stage surgery (N=30) and one-stage surgery (N=46). OUTCOME MEASURES Not applicable. METHODS Comparisons between groups were made regarding the following variables: gender, age at surgery, follow-up duration, number of segments, duration of surgery, hospitalization time, and different radiological parameters. The anteroposterior (AP) and lateral standing radiographs were used to check for deformity; numbers of instrumented segments, curve flexibility (bending test), coronal and sagittal balance and rotation deformity. The coronal balance was measured as the distance between the C7 plumb line and the perpendicular line drawn from the center of S1. The sagittal balance was measured as shortest distance between the C7 plumb line and the posterior superior corner of the S1 body. For both coronal and sagittal measurements, balance was considered abnormal if the distance was greater than 2 cm. Measurement of vertebral rotation was done using the Nash-Moe method. All patients were invited in an outpatient clinic to fill out a short-form health survey (SF-36) and to make a control X-ray image of the whole spine. RESULTS No statistically significant difference was observed in correction between two-stage group (average correction 69%) and only posterior approach group (average correction 66%). However, there were statistically significant differences regarding hospitalization time, duration of the surgery and the number of instrumented segments. The SF-36 scores were similar and there were no statistically significant differences between different health dimensions among compared groups. The greatest differential found in mean scores was for energy and vitality. CONCLUSIONS Two-stage surgery has only a limited advantage in terms of postoperative correction angle compared to the posterior approach. Posterior instrumentation and correction is satisfactory, especially taking into account that the patient is subjected to only one surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

ROTATION ASSESSMENT IN ADOLESCENT IDIOPATHIC SCOLIOSIS WITH ROD DEROTATION.

ABSTRACTObjective:Adolescent idiopathic scoliosis (AIS) is characterized by rotational and lateral deformity of the spine. The measurement of vertebral rotation is important for prognosis and treatment. Our objective was to evaluate whether the Nash-Moe method can be used to measure axial deformity correction with surgical treatment using the rod derotation maneuver at both the apex and extremities of the deformity in patients with AIS.Methods:Rotation was assessed using the Nash and Moe criteria, on preoperative and postoperative radiographs. We also evaluated the severity on the coronal plane using the Cobb method, ratio of correction achieved, screw density, and number of vertebrae involved in the instrumentation.Results:The Cobb method correction average was 54.8%. When we disregarded vertebrae that presented preoperative Nash-Moe grade 0, the average measurable correction was 54.5% in the first non-instrumented vertebra above, 69.2% in the first instrumented vertebra, 32.2% in the apical vertebra, 36.8% in the last instrumented vertebra, and 30% in the first non-instrumented vertebra below. In our study, 32.14% of the patients presented a measurable correction in the apical vertebra.Conclusion:On the axial plane, correction can be satisfactorily evaluated using the Nash-Moe method. Level of Evidence VI. Case Series.

Measurement of Vertebral Rotation from Moire Image for Screening of Adolescent Idiopathic Scoliosis

Measurement of Vertebral Rotation from Moire Image for Screening of Adolescent Idiopathic Scoliosis

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.

Validity Study of Vertebral Rotation Measurement Using 3-D Ultrasound in Adolescent Idiopathic Scoliosis

This study aimed to assess the validity of 3-D ultrasound measurements on the vertebral rotation of adolescent idiopathic scoliosis (AIS) under clinical settings. Thirty curves (mean Cobb angle: 21.7° ± 15.9°) from 16 patients with AIS were recruited. 3-D ultrasound and magnetic resonance imaging scans were performed at the supine position. Each of the two raters measured the apical vertebral rotation using the center of laminae (COL) method in the 3-D ultrasound images and the Aaro-Dahlborn method in the magnetic resonance images. The intra- and inter-reliability of the COL method was demonstrated by the intra-class correlation coefficient (ICC) (both [2, K] >0.9, p < 0.05). The COL method showed no significant difference (p < 0.05) compared with the Aaro-Dahlborn method. Furthermore, the agreement between these two methods was demonstrated by the Bland-Altman method, and high correlation was found (r > 0.9, p < 0.05). These results validated the proposed 3-D ultrasound method in the measurements of vertebral rotation in the patients with AIS.

Reliability of the axial vertebral rotation measurements of adolescent idiopathic scoliosis using the center of lamina method on ultrasound images: in vitro and in vivo study.

This study aimed to investigate the intra- and inter-observer reliability of the axial vertebral rotation (AVR) measurements of adolescent idiopathic scoliosis (AIS) using the center of lamina (COL) method on ultrasound transverse images. Three cadaver vertebrae were scanned with 42 AVR configurations by both ultrasound and radiograph. In this in vitro study, four observers measured the AVR using the COL method on ultrasound transverse images and three observers measured the AVR using the Stokes' method on radiographs. In the in vivo study, 13 AIS subjects were recruited. Eighteen spinal curvatures were identified and 48 vertebrae were selected for the AVR measurements. Two observers performed the AVR measurements on both the ultrasound images and radiographs. All measurements were performed twice with 1week interval apart to reduce memory bias. The intraclass correlation coefficient (ICC), mean absolute differences (MAD), and standard deviation (SD) were used to analyze the intra- and inter-observer reliability of the AVR measurements. The Bland-Altman plot was used to analyze the 95% limit of the differences between the two methods. The proposed COL method had high intra- and inter-observer reliability on both the in vitro and in vivo studies (ICCs>0.91, MADs<1.4°) and agreed well with the experimental setup (ICCs>0.96, MADs<2.3°). The COL method showed good agreement with the Stokes' method for the in vitro study (ICC 0.84-0.85, MAD 4.5°-5.0°), while poor agreement for the in vivo study (ICC 0.49-0.54, MAD 2.7°-3.5°). The pilot study indicated the proposed COL method was a simple and reliable method to evaluate the AVR on ultrasound images. Standardization of the posture during ultrasound scan and taking radiograph is important.

Maintenance of Derotation in Adolescent Idiopathic Scoliosis: a Novel Technique Measuring Postoperative Vertebral Rotation by Pedicle Screw Position.

Current methods of measuring vertebral rotation by plain radiographs rely on anatomic landmarks that are not present in the postoperative spine or require advanced imaging. Furthermore, there are few studies on the incidence of crankshaft with modern pedicle instrumentation. We sought to (1) describe and validate a method of vertebral rotation measurement using plain radiographs and (2) measure postoperative rotation in a series of patients treated for adolescent idiopathic scoliosis. Patients with adolescent idiopathic scoliosis treated with surgery over a 6-year period were reviewed. Patients with computed tomography (CT) scans and radiographs within 60days of another were included. Vertebral rotation was calculated by radiographic measurements and measured directly by CT scan. As an internal control, patients with two apical pedicle screws on all radiographs were analyzed. Rotation was measured for all patients with at least 1year of radiographic follow-up. Three thousand five hundred fifty-two instrumented spinal levels in 308 consecutive patients were reviewed. Ten patients with 93 screws were analyzed by CT and radiographs. The average discrepancy between computed tomography (CT) and radiographs was 3.3 ± 1.9°, with 81.7% (76/93) within 5°. Intra- and inter-rater reliabilities for measured axial rotation were excellent (intra-class correlation coefficient (ICC) = 0.879 and 0.900, respectively). One hundred swventy-eight patients were eligible with an average follow-up of 2.3 ± 1.2years; 84.8% (151/178) had screw(s) visible on all images at the major curve apex. The average postsurgical rotation was 3.5 ± 2.9°; 19.2% (29/151) were measured to have a rotation over 5°, and 4.0% (6/151) demonstrated a rotation over 10°. Only 4.6% (7/151) of patients demonstrated a postoperative Cobb angle change over 10°. Most major curves have apical pedicle screw instrumentation that can be followed by radiographs alone to measure rotation. Vertebral rotation measurement requires only plain radiographs and is a more sensitive determination for subtle postoperative crankshaft than change in Cobb angle.

Measurement of vertebral rotation using a three-dimensional ultrasound image

Materials and methods Three cadaveric vertebrae T7, L1, and L3 were scanned with a 3D medical ultrasound system. The rotation angles of the cadaveric vertebra were recorded during the experiment. Nine sets of ultrasound data, from 0 to 40° with 5° increments, were recorded from each vertebra (27 sets in total). An in-house program was used to reconstruct the 3D vertebra images. The rotation of each reconstructed vertebra was determined by the angle between the line going through either the centres of laminae (L-L) or the centres of transverse processes (TPTP) and a reference vertical plane. This reference plane was defned from the position sensor parallel to the surface of the transducer. Three raters, who were blinded with the rotation information, used the images to measure the rotation in 3 sessions. In each session, the raters used the mouse pointer to select L-L or TP-TP according to their knowledge of vertebral anatomy. The program received the 3D coordinates of these points and calculated the VR. Intra-class correlation coefficients (ICCs) (two-way random and absolute agreement) were used to calculate the intraand inter-reliability. The mean absolute difference (MAD±SD) and the range of difference (RD) between the true values and the average measurements of each rater were also computed to evaluate the accuracy of methods. Results When rotation was greater than 30° for both L1 and L3, all raters found it difficult to determine one of the lamina areas because it could not be displayed due to ultrasound blocking. Therefore, the corresponding measurements were excluded. The intra-reliability (L-L, TP-TP) for the three raters were (0.987, 0.991), (0.989, 0.998) and (0.997, 1.000), respectively; meanwhile, the inter-reliability were 0.991 for (L-L) and 0.992 for (TP-TP). All ICC values were greater than 0.98 indicating both methods were highly reliable. The MAD±SD values (L-L, TP-TP) for the three raters were (1.5±0.3°, 1.2±0.2°), (1.6±0.3°,1.3 ±0.3°), and (1.7±0.5°, 0.9±0.2°), respectively. The RD (L-L, TP-TP) were (0-4.5°, 0-3.5°), (0-5.1°, 0-4.3°), and (0-5.1°, 0-2.8°) for the three raters, respectively.

The radiographic method for evaluation of axial vertebral rotation - presentation of the new method.

The objective of this study is to present a new radiographic method for the assessment of vertebral rotation from an antero-posterior view of conventional X-rays which is sufficiently precise in comparison with radiographic methods presently used in clinical practice (methods of Nash-Moe and Perdriolle). This method is based on the properties of the geometric shape of vertebrae and their shared dimensional proportions. It means that the relation between vertebral body width and height doesn’t change significantly within the entire thoracic and lumbar sections of the spine. In order to verify the method, we have constructed a special device for vertebral fixation. Subsequently, the X-ray pictures of individual human vertebrae with predefined rotation values (ranging from 0 degrees to 45 degrees by steps of 3 degrees) were radio-graphically measured and then compared with their actual axial rotation on the vertebral rotation device. All arithmetic averages correlate very closely with the actual values. The verification of axial vertebral rotation with the assistance of CT and MRI pictures of six scoliotic patients (in supine position) and the evaluation of axial vertebral rotation by both the new radiographic method and with the Perdriolle method proved the satisfactory accuracy of our method. The main advantage of the newly presented radiographic method is the uncomplicated measurement of vertebral rotation from AP projection of conventional X-ray pictures or from its printed copies. The gold standard of the new radiographic method is the evaluation of axial rotation of vertebrae to 30 degrees approximately and the shape of vertebral bodies without severe structural deformities. The new radiographic method seems to be suitable for use in clinical practice.

Three-dimensional imaging of the spine using the EOS system

The aim of this study was to evaluate the precision of three-dimensional geometry compared with computed tomography (CT) images. This retrospective study included patients who had undergone both imaging of the spine using the EOS imaging system and CT scanning of the spine. The apical vertebral orientation was also measured using the EOS imaging system and by CT. Other measures such as the Cobb angle and apical vertebral rotation and translation were used as the control variables to evaluate the potential discrepancy between the standing position in EOS imaging and the supine position in CT scanning. The apical vertebral orientations were 8.7° for the first measurement and 8.4° for the second measurement made by the first author, and 10.3° for the measurement made by the second author. The average of these measurements was 9.3° compared with 6.6° (P=0.65) obtained on CT scanning. The precision of EOS-based measurements of vertebral rotation has never been tested in clinical practice. Although it has limitations, this study suggests that the results obtained using EOS are comparable to those obtained on CT.

Is Radiation-Free Diagnostic Monitoring of Adolescent Idiopathic Scoliosis Feasible Using Upright Positional Magnetic Resonance Imaging?

Prospective clinical trial. The purpose of this study was to determine if an upright positional magnetic resonance imaging (MRI) protocol could produce reliable spinal curvature images and measurements compared with traditional radiograph. Concerns about the oncological potential from cumulative doses of ionizing radiation in children and adolescents being monitored for adolescent idiopathic scoliosis (AIS) initiated a search for radiation-free diagnostic imaging modalities, including MRI. We submit that upright, positional MRI (uMRI) produces reliable spinal curvature images compared with traditional radiograph. Twenty-five consecutive patients (16 female; 9 male; average age, 14.6 yr; range, 12-18 yr) with a diagnosis of AIS were enrolled. Average major curve magnitude was 30° (range, 6°-70°). Subjects received anterior-posterior and lateral plain radiographical scoliosis imaging followed within 1 week by uMRI. MRI data acquisition was performed in less than 7 minutes. Two independent observers performed all Cobb angle, T5-T12 kyphosis, and vertebral rotation measurements for comparison. The Pearson correlation method was performed to compare radiograph to uMRI measurements, while inter-rater and intrarater correlations were performed to assess reliability. We found outstanding correlation between all plain film radiography and uMRI measurements (P = 0.01); major Cobb angles (R = 0.901), minor Cobb angles (R = 0.838), and kyphosis (R = 0.943). Inter-rater reliability for both radiographical and MRI measurements of major Cobb angles (R = 0.959, 0.896, respectively), minor Cobb angles (R = 0.951, 0.857, respectively), and vertebral rotation (R = 0.945) were outstanding. Intrarater reliability for both radiographical and MRI measurements of major Cobb angles (R = 0.966, 0.966, respectively) and minor Cobb angles (R = 0.945, 0.943, respectively) were also outstanding. Our results show that uMRI is capable of producing coronal and sagittal plane measurements that highly correlate with traditional plain film radiographical measurements. This, in addition to reliable vertebral rotation measurements, makes uMRI a valuable, radiation-free alternative/substitute for diagnostic evaluation in AIS.

Breakthrough in three-dimensional scoliosis diagnosis: significance of horizontal plane view and vertebra vectors

Scoliosis is a multifactorial three-dimensional (3D) spinal deformity with integral and directly related vertebral deviations in the coronal, sagittal and horizontal planes. Current classification and diagnostic methods rely on two-dimensional (2D) frontal and lateral X-ray images; no routine methods are available for the visualization and quantitative evaluation of deviations in the horizontal plane. The EOS 2D/3D system presented here is a new, low-dose, orthopedic radiodiagnostic device based on Nobel prize-winning X-ray detection technology with special software for 3D surface reconstruction capabilities that finally led to a breakthrough in scoliosis diagnosis with high-quality, realistic 3D visualization and accurate quantitative parametric analysis. A new concept introducing vertebra vectors and vertebra vector parametric calculations is introduced that furnishes simplified visual and intelligible mathematical information facilitating interpretation of EOS 2D/3D data, especially with regard to the horizontal plane top view images. The concept is demonstrated by a reported scoliotic case that was readily characterized through information derived from vertebra vectors alone, supplemented with the current angulation measurement methods in the coronal and sagittal planes and axial vertebral rotation measurements in the horizontal plane, with a calibrated 3D coordinate system suitable for inter-individual comparisons. The new concept of vertebra vectors may serve as a basis for a truly 3D classification of scoliosis.

Technical error of vertebral rotation measurement directly on the computer screen, according to Raimondi method

The purpose of the study was to check the intrarater reliability of the Raimondi system measuring vertebral rotation directly on a computer screen.

Measurement of vertebral rotation in adolescent idiopathic scoliosis with low-dose CT in prone position - method description and reliability analysis.

BackgroundTo our knowledge there is no report in the literature on measurements of vertebral rotation with low-dose computed tomography (CT) in prone position.AimsTo describe and test the reliability of this new method, compare it with other methods in use and evaluate the influence of body position on the degree of vertebral rotation measured by different radiological methods.Study designRetrospective study.Methods25 consecutive patients with adolescent idiopathic scoliosis scheduled for surgery (17 girls, 8 boys) aged 15 ± 2 years (mean ± SD) were included in the analysis of this study. The degree of the vertebral rotation was in all patients measured according to the method of Perdriolle on standing plain radiographs and on supine CT scanogram, and according to the method of Aaro and Dahlborn on axial CT images in prone position and on magnetic resonance imaging (MRI) in supine position. The measurements were done by one neuroradiologist at two different occasions. Bland and Altman statistical approach was used in the reliability assessment.ResultsThe reliability of measuring vertebral rotation by axial CT images in prone position was almost perfect with an intraclass correlation coefficient of 0.95, a random error of the intraobserver differences of 2.3°, a repeatability coefficient of 3.2° and a coefficient of variation of 18.4%. Corresponding values for measurements on CT scanogram were 0.83, 5.1°, 7.2°, and 32.8%, respectively, indicating lower reliability of the latter modality and method. The degree of vertebral rotation measured on standing plain radiographs, prone CT scanogram, axial images on CT in prone position and on MRI in supine position were 25.7 ± 9.8°, 21.9 ± 8.3°, 17.4 ± 7.1°, and 16.1 ± 6.5°, respectively. The vertebral rotation measured on axial CT images in prone position was in average 7.5% larger than that measured on axial MRI in supine position.ConclusionsThis study has shown that measurements of vertebral rotation in prone position were more reliable on axial CT images than on CT scanogram. The measurement of vertebral rotation on CT (corrected to the pelvic tilt) in prone position imposes lower impact of the recumbent position on the vertebral rotation than did MRI in supine position. However, the magnitude of differences is of doubtful clinical significance.

The treatment of adolescent idiopathic scoliosis with Cheneau brace: long term outcome

Methods The inclusion criteria included the following: diagnosis of evolutive idiopathic scoliosis (I.S.), exclusive treatment with the Cheneau brace, at least 30 months of treatment, and a minimum follow up of 20 months. Every patient was studied with anamnesis, clinic exam, and a radiographic examination. The following was obtained from the medical history: age, sex, BMI, type of scoliosis, period of treatment, type or protocol of treatment, time of follow-up, old radiographic collection, and re-evaluation of all curves with the Cobb method. All patients were asked to complete a five-question questionnaire (SRS-22 modified) about treatment satisfaction and to write a commentary about the main difficulties of treatment. At clinic examination, all anatomic findings were evaluated (height and weight, BMI, rib hump, shoulders and trunk asymmetry, etc.). The radiographic film was compared with old exams, evaluated with Cobb angle measurements, and measurements of vertebral rotation.

Validity and reliability of a computer method to estimate vertebral axial rotation from digital radiographs

Axial vertebral rotation, an important parameter in the assessment of scoliosis may be identified on X-ray images. In line with the advances in the field of digital radiography, hospitals have been increasingly using this technique. The objective of the present study was to evaluate the reliability of computer-processed rotation measurements obtained from digital radiographs. A software program was therefore developed, which is able to digitally reproduce the methods of Perdriolle and Raimondi and to calculate semi-automatically the rotation degree of vertebra on digital radiographs. Three independent observers estimated vertebral rotation employing both the digital and the traditional manual methods. Compared to the traditional method, the digital assessment showed a 43% smaller error and a stronger correlation. In conclusion, the digital method seems to be reliable and enhance the accuracy and precision of vertebral rotation measurements.

Vertebral rotation measurement: a summary and comparison of common radiographic and CT methods

Current research has provided a more comprehensive understanding of Adolescent Idiopathic Scoliosis (AIS) as a three-dimensional spinal deformity, encompassing both lateral and rotational components. Apart from quantifying curve severity using the Cobb angle, vertebral rotation has become increasingly prominent in the study of scoliosis. It demonstrates significance in both preoperative and postoperative assessment, providing better appreciation of the impact of bracing or surgical interventions. In the past, the need for computer resources, digitizers and custom software limited studies of rotation to research performed after a patient left the scoliosis clinic. With advanced technology, however, rotation measurements are now more feasible. While numerous vertebral rotation measurement methods have been developed and tested, thorough comparisons of these are still relatively unexplored. This review discusses the advantages and disadvantages of six common measurement techniques based on technology most pertinent in clinical settings: radiography (Cobb, Nash-Moe, Perdriolle and Stokes' method) and computer tomography (CT) imaging (Aaro-Dahlborn and Ho's method). Better insight into the clinical suitability of rotation measurement methods currently available is presented, along with a discussion of critical concerns that should be addressed in future studies and development of new methods.

Predicting Intraoperative Vertebral Rotation in Patients With Scoliosis Using Posterior Elements as Anatomical Landmarks

A retrospective study. To predict intraoperative vertebral rotation in patients with scoliosis using posterior elements as anatomic landmarks. In patients with scoliosis, accurate intraoperative vertebral rotation measurements are needed to avoid spinal cord injury caused by pedicle screw misplacement. Generally, we predict vertebral rotation by anatomic landmarks, that is, posterior elements that can be seen during surgery, such as spinous processes, transverse processes, or laminae. However, correlation between vertebral rotation and these anatomic landmarks is unclear. Seventy-six vertebrae (T4-T12) of 17 patients with thoracic scoliosis were measured. Patients who had severe scoliosis (>90 degrees Cobb angle) were excluded from this study. We assessed apex and adjacent vertebrae using axial computed tomography scans taken with patients in a supine position. We measured the angle between the vertebral reference line (Ve), defined as the midline of the vertebral body, and various lines based on the following anatomic landmarks of posterior elements of the vertebrae: (a) The Spinous q process line (Sp), defined as the midline of the spinous process; (b) A bisector (Bi) of the bilateral lines that pass the depressions in the laminae to the medial apex of the transverse processes; (c) a line (Tr) perpendicular to a line which passes the bilateral transverse processes; and (d) a line (La) perpendicular to the line which passes the bilateral depressions in the laminae. The average Cobb angle in A-P radiographs was 68 degrees. The average angles between Sp, Bi, Tr, and La and the vertebral reference line were 13.6 degrees (range 0 degrees -29.2 degrees), 3.0 degrees (range 0 degrees -9.0 degrees), 2.5 degrees (range 0 degrees -8.1 degrees), and 4.4 degrees (range 0 degrees -11.9 degrees), respectively. The line Tr, (runs perpendicular to the line which passes the bilateral transverse processes) had the greatest correlation to the rotation of a vertebra. On the other hand, the line Sp (defined as the midline of the spinous process) was not sufficient for predicting rotation of a vertebra and can be disregarded during the intraoperative analysis and screw placement.