The Open Orthopaedics Journal




ISSN: 1874-3250 ― Volume 13, 2019

Reproducibility of Newly Developed Spinal Topography Measurements for Scoliosis



Leah Rankine 1, Xue C Liu*, 1, Channing Tassone 1, Roger Lyon 1, Sergey Tarima 2, John Thometz 1
1 Department of Orthopaedic Surgery, Children’s Hospital of Wisconsin, Medical College of Wisconsin, Milwaukee, WI, USA
2 Department of Biostatistics, Medical College of Wisconsin, Milwaukee, WI, USA

Abstract

Objective:

In an effort to limit exposure to ionizing radiation and fully characterize three dimensional changes in the spine of patients with scoliosis reliable non-invasive methods of spinal back contour analysis (Milwaukee Topographic Scanner) (MTS) have been developed.

Study Design:

The current study compares spinal topography measurements among different subject positions and evaluates the reproducibility of the system for both inter-rater and intra-rater reliability.

Methods:

A dummy cast (plastic cast) of one patient with adolescent idiopathic scoliosis was created in order to test the reliability of the MTS. The dummy cast was positioned and rotated in 3D while scanned by two investigators using the MTS. A total of twelve parameters including Q-angle (an analog to X-ray’s Cobb angle) were extracted.

Results:

All measurements of intra-rater and inter-rater reliability were excellent (Intraclass Correlation Coefficients ranging from 0.89 to 0.99) with the exception of Pelvic Tilt (intra-rater ICC is 0.61) and lordosis angle (inter-rater ICC is 0.82). No significant variability among investigators was observed for all tested metrics. No significant variability due to position was observed for the majority of back contour measurements but there were significant changes in the T1-S1 angle, T1-S1 deviation, T1-NC angle, T1-NC deviation, and Back Height metric (p< 0.05).

Conclusions:

The MTS is a reliable method of raster stereography in the measurement of the back contour, which will help monitor the progression of children with idiopathic scoliosis and reduce the use of X-rays.

Keywords: Scoliosis, rastersterography, imaging, topography, reproducibility.


Article Information


Identifiers and Pagination:

Year: 2012
Volume: 6
First Page: 226
Last Page: 230
Publisher Id: TOORTHJ-6-226
DOI: 10.2174/1874325001206010226

Article History:

Received Date: 18/11/2011
Revision Received Date: 14/2/2012
Acceptance Date: 8/3/2012
Electronic publication date: 15/6/2012
Collection year: 2012

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© Rankine et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.


* Address correspondence to this author at the Musculoskeletal Functional Assessment Center, Children’s Hospital of Wisconsin, Department of Orthopaedic Surgery, 9000 W Wisconsin Ave, C360, Milwaukee, WI 53226, USA; Tel: (414) 337 7323; Fax: (414) 337 7337; E-mail: xliu@chw.org




INTRODUCTION

Children with Idiopathic Scoliosis present with three dimensional deformities which are assessed by radiographic evaluation. This method of assessment does not account for three dimensional changes in the spine and exposes patients to ionizing radiation which has been shown to increase the risk of developing several types of cancers, including breast and thyroid cancers [1 Nash CL Jr, Gregg EC, Brown RH, Pillai K. Risks of exposure to X-rays in patients undergoing long-term treatment for scoliosis J Bone Joint Surg Am 1979; 61(A3): 371-4.-3 Ronckers CM, Land CE, Miller JS, Stovall M, Lonstein JE, Doody MM. Cancer mortality among women frequently exposed to radiographic examinations for spinal disorders Radiat Res 2010; 174(1): 83-90.]. In order to address these issues, noninvasive methods of spinal curve analysis such as Moiré photography [4 Daruwalla JS, Balasubramaniam P, Chay SO. Idiopathic scoliosis. Prevalence and ethnic distribution in Singapore schoolchildren J Bone Joint Surg Br 1985; 67(2): 182-4., 5 Denton TE, Randall FM, Deinlein DA. The use of instant moire photographs to reduce exposure from scoliosis radiographs Spine 1992; 17(5): 509-12.], ultrasound-guided spine analysis (Zebris) [6 Malmström EM, Karlberg M, Melander A, Magnusson M. Zebris versus Myrin: a comparative study between a three-dimensional ultrasound movement analysis and an inclinometer/compass method: intradevice reliability, concurrent validity, intertester comparison, intratester reliability, and intraindividual variability Spine 2003; 28(21): E433-40.], Integrated Shape Imaging System (ISIS) [7 Theologis TN, Jefferson RJ, Simpson AHRW, Turner-Smith AR, Fairbank JCT. Quantifying the cosmetic defect of adolescent idiopathic scoliosis Spine 1993; 18(7): 909-12., 8 Theologis TN, Fairbank JCT, Turner-Smith AR, Pantazopoulos T. Early detection of progression in adolescent idiopathic scoliosis by measurement of changes in back shape with the integrated shape imaging system scanner Spine 1997; 22(11): 1223-8.], and the Quantec Spinal Imaging System (QSIS) [9 Thometz J, Liu XC, Harris GF. Computerized evaluation of the surface measurement of kyphosis and lordosis in idiopathic scoliosis In: Proceedings of the 20th International Conference of the IEEE Engineering in Medicine and Biology; 1998 Oct 28–Nov 1; Hong Kong. 1998; pp. 2507-8.-15 Goldberg CJ, Kaliszer M, Moore DP, Fogarty EE, Dowling FE. Surface topography, Cobb angles, and cosmetic change in scoliosis Spine 2001; 26(4): E55-63.] were developed. Although QSIS has been repeatedly studied and found to be a reliable and accurate measurement of spinal deformity, its use remains limited among practitioners [12 Schulte TL, Hierholzer E, Boerke A, et al. Raster stereography versus radiography in the long-term follow-up of idiopathic scoliosis J Spinal Disord Tech 2008; 21(1): 23-8.-18 Thometz JG, Liu XC, Lyon R, Harris GF. Variability in three-dimensional measurements of back contour with raster stereography in normal subjects J Pediatr Orthop 2000; 20(1): 54-8.].

The current Quantec system can be operated by nonspecialized personnel but data acquisition is tedious and time consuming; especially because the operating system is antiquated. To address these issues, we have developed a new user-friendly raster stereography system (Milwaukee Topographic Scanner, MTS) composed of a new software system, handheld light source, and hardware which can be easily transported among clinic rooms. The goal of the current study is to compare MTS measurements among different subject positions and to evaluate the reproducibility of MTS for both inter-rater and intra-rater.

MATERIALS AND METHODS

A dummy cast was created using a plastic model of one patient with adolescent idiopathic scoliosis. Optical color-coded markers were placed on each of the cast’s spinous process landmarks from T1 to L5 and at each posterior superior iliac spine (PSIS). The MTS is composed of measurement software, a sensor, a laser light, two cameras in one handle and hardware. Two investigators completed a series of three MTS scans of the dummy cast in each of four different positions (conditions): flexed 10° forward in the sagittal plane (10°F), flexed 20° forward in the sagittal plane (20°F), rotated 10° in the transverse plane (10T°), and “shaking” (SH) back and forth in the coronal plane for a total of 24 scans (12 scans per investigator). After each measurement was taken the dummy cast was rotated using a goniometer according to the aforementioned degrees. After scanning, 14 clinically relevant metrics and 3D back contour image were extrapolated from the MTS 3D data (Fig. 1A, B):

Fig. (1)

(A) A dummy cast with markers on the spinal process from T1 to L5 was scanned by the MTS system: three Q angles (8°, 21°, and 15°) are analogous to Cobb angles in the coronal plane; (B) Kyphosis (36°) and lordosis (25°) are analogous to Cobb angles in the sagittal plane.



  1. Q angle: maximum angle of tilt in the coronal plane, analogous to Cobb angle in the coronal plane (Fig. 1A);
  2. Area of Back: total back area between the T1 and T12;
  3. Area Percentage in left and right (%): Area of left or right side of back divided by a line from T1 to T12 vs total area of back then multiplied by 100;
  4. Area of Back ratio: area on the left vs on the right;
  5. Kyphosis/ Lordosis: maximum angle of tilt in the sagittal plane (T1-T12 for Kyphosis and L1-S1 for Lordosis), analogous to Cobb angle in the sagittal plane (Fig. 1B);
  6. Suzuki Hump Sum: Measurement of rib hump asymmetry based on three lateral cross sections. This measurement is indicative of transverse rotation [19 Suzuki N, Tezuka M, Toshiaki T. Scoliosis follow-up by back shape analysis: Evaluation of its reliability In: Amico MA, Merolli A, Santambrogio GC, Eds. Three-dimensional analysis of spinal deformities. Amsterdam: IOS Press 1995; pp. 405-8.];
  7. POTSI (posterior trunk symmetry index): Coronal plane measurement calculated by measurement of several variables including waist creases and shoulder heights [20 Suzuki N, Inami K, Ono T, Kohno K, Asher MA. Analysis of posterior trunk symmetry (POTSI) in scoliosis In: Strokes IAF, Ed. Research into Spinal Deformities 2. Amsterdam: IOS Press 1999; pp. 81-4.];
  8. Volume of Interest (VOI): a measurement in the transverse (axial) plane from the most posterior point on each vertebral body perpendicular to a coronal vertical plane made by the shoulders;
  9. T1-S1 angle: the angle between the laboratory vertical and the anteroposterior projection of the line passing through T1 and S1[11 Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.];
  10. T1-S1 Deviation: the horizontal distance (mm) at S1 between the laboratory vertical and the anteroposterior projection of the line passing through T1 and S1 [11 Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.];
  11. T1-NC angle: the angle between the laboratory vertical and the anteroposterior projection of a line passing through the top of the natal cleft [11 Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.];
  12. T1-NC deviation: the horizontal distance at the natal cleft between the laboratory vertical and a line passing through the top of the natal cleft [11 Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.];
  13. Back Height: the distance between T1 and the bisector of the posterior superior iliac spines [11 Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.];
  14. Pelvic Tilt: the angle between the laboratory horizontal and the posterior superior iliac spines in the coronal plane (pelvic obliquity) [11 Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.];

Fixed effects repeated analysis of variance measurements (ANOVAs) were calculated for each of the 14 metrics. A separate ANOVA procedure was performed for each metric in order to assess variability due to each individual position condition (10°F, 20°F, 10T°, and SH) as well as trial and investigator variables. A statistical model was designed: where β0 defines overall intercept for the measured parameter, is a vector of 3 parameters adjusting our model for POSITION effect, β2 is INVESTIGATOR effect, β3 is the effect of replicating the measurement of the same INVESTIGATOR at the same POSITION, εijk is a measurement error following a normal distribution with a zero mean and an unknown variance σ2.

Intraclass correlation coefficients (ICC’s) were also calculated to assess contribution of intra-rater and inter-rater variability to total variability. The ICC value (1.0) is considered as highest reproducibility. P <0.05 was considered as significant difference.

RESULTS

No significant variability due to position, investigator, or trial was observed in the following metrics: Area of Back, Area%, Area Ratio, Kyphosis, Lordosis, Suzuki Hump Sum, POTSI, Volume of Interest, or Q-angle (Table 1). Q angle for the dummy cast curve (i.e., thoracic curve) was measured with the mean value of 19.3° (ranging from 16° to 22°). Differences of Q angles between the investigators was 1.5° (ranging from 0 to 3°) and differences of Q angles among trials was 1.4° (ranging from 0 to 6°) (Fig. 2). Significant variability due to position was observed in the T1-S1 angle, T1-S1 deviation, T1-NC angle, T1-NC deviation, and Back Height (p < 0.01, p = 0.03, p <0.01, p < 0.01, p < 0.001, respectively). Standard error (SE) for trial variability ranged from 0.1 (Area ratio) to 8.1 (POTSI).

Table 1

Determinants of Significance (p Values) and Standard Error (SE) for Each Metric




Table 2

Intraclass Correlation Coefficients for Intra-Observer and Inter-Observer in 14 Metrics




Fig. (2)

Changes of analogous to Cobb angle between investigators, trials, and different positions (mean value in degrees) (NEU = neutral position; I1T1/I1T2: investigator: for trial 1 or 2; I2T1/I2T2: investigator 2 for trial 1 or 2).



Significant variability was observed in the 20°F condition for the T1-S1 angle (p=0.002), T1-S1 deviation (p=0.01), T1-NC angle (p=0.02), and T1-NC deviation (p=0.02) metrics. Variability due to 10°F condition, the 10°T condition, and the SH condition were not significant in any of these metrics. With respect to the Back Height metric, all position variables (10°F, 20°F, 10°T, and SH) resulted in significant variability (p<0.0001 p<0.001, p<0.0001, p<0.001 respectively). Significant variability was also observed in the trial variable for the Pelvic Tilt metric (p=0.03). For the VOI metric, no significant variability was observed in the overall position variable but significant variability was observed in the shaking condition (p=0.03).

Intraclass Correlation Coefficients (ICCs) demonstrated inter-rater reliability of less than 1.0 for the following metrics: Area of Back, Area Ratio, and Lordosis (0.82-0.90) (Table 2). All other metrics of inter-rater ICC were equal to 0.99. With respect to Intra-rater ICCs, only the pelvic tilt metric was less than 1.0 (ICC=0.61). All other Inter-rater ICCs were equal to 0.99.

DISCUSSION

Our data indicate that the MTS is reliable and reproducible for the majority of the tested measurement parameters (Tables 1 and 2). Since the markers on the casting dummy remained in a constant position, variation in the measurements could be traced to differences in dummy position and investigator scanning technique. While several methods of raster sterography have been published, data from this study are most comparable to data reported for Quantec systems. Investigating QSIS measurements in 200 patients with idiopathic scoliosis, Wojcik et al. reported a SE for thoracic Q-angle of 4.8° while the thoracic Q-angle SE in our study was 0.93° [21 Wojcik AS, Philips GF, Mehta MH. Recording of the back surface and spinal shape by the Quantec Image System: A new technique in the scoliosis clinic J Bone Joint Surg Br 1994; 76: 10.]. Most notably, thoracic Q-angle SE reported in this study is less than SE in Cobb angle reported in the literature (SE=1.7°) [22 Morrissy RT, Goldsmith GS, Hall EC, Kehl D, Cowie GH. Measurement of the Cobb angle on radiographs of patients who have scoliosis. Evaluation of intrinsic error J Bone Joint Surg Am 1990; 72(3): 320-7.]. Mean Q angle difference between the investigators (1.5°) and between trials (1.4°) regardless of position demonstrated that the measurement of curvature by the MTS can be reproduced by difference clinicians and is not limited by patient positioning. Additionally, no other parameters tested with the MTS demonstrated significant variability due to either trial or observer, with the exception of the Pelvic Tilt metric among trials. Variation in the Pelvic Tilt metric may be explained by variation in identification of the PSIS and is a limitation of the technique common to all rasterstereogrpahic technologies. However, identification of the PSIS is used only in this metric and has impact on spinal curve measurements.

Our data support previous research by Stokes and Moreland and by Liu et al. indicating that trunk position has an effect on surface topography measurements [10 Liu XC, Thometz JG, Lyon RM, McGrady L. Effects of trunk position on back surface-contour measured by raster stereophotography Am J Orthop (Belle Mead NJ) 2002; 31(7): 402-6., 23 Stokes IAF, Moreland MS. Measurement of the shape of the surface of the back in patients with scoliosis. The standing and forward-bending positions J Bone Joint Surg Am 1987; 69(2): 203-11.]. In contrast, Sakka et al. found no variability in QSIS measurements due to trunk position [24 Sakka SA, Wojcik A, Macindoe S, Mehta MH. Three-dimensional analysis of spinal deformity. Stanmore, England: IOS Press 1995; pp. 111-5.], although different metrics were tested in each of these studies. In the current study significant variability due to position was observed in the T1-S1 angle, T1-S1 deviation, T1-NC angle, and T1-NC deviation metrics (p<0.01, p=0.03, p<0.01, p<0.01, p<0.001, respectively). This data supports that of Liu et al., who also reported significant variability in these metrics due to forward rotation [10 Liu XC, Thometz JG, Lyon RM, McGrady L. Effects of trunk position on back surface-contour measured by raster stereophotography Am J Orthop (Belle Mead NJ) 2002; 31(7): 402-6.]. However, this variability was only related to the 20°Foward position. This effect may be a result of the sensors which are placed on the subject’s back which decrease measurement noise and could result in dampening of variability caused by small changes in position.

Our data do not support previous research which indicates significant variability in the Kyphosis metric due to forward bending, indicating that the MTS is more reproducible with respect to this parameter than previous QSIS systems [10 Liu XC, Thometz JG, Lyon RM, McGrady L. Effects of trunk position on back surface-contour measured by raster stereophotography Am J Orthop (Belle Mead NJ) 2002; 31(7): 402-6., 23 Stokes IAF, Moreland MS. Measurement of the shape of the surface of the back in patients with scoliosis. The standing and forward-bending positions J Bone Joint Surg Am 1987; 69(2): 203-11.]. Significant variability of VOI reported in the SH metric may be due to inconsistent manual movement of the dummy cast during testing and may also indicate the sensitivity of this metric to changes due to postural sway in the coronal plane.

Variability in the Back Height metric due to trunk position (p<0.001) has not been studied previously but variability in this metric with changes in position of the trunk is expected. Because back height is measured vertically and tilting of the dummy cast forward in the 10°F, 10°T, 20°F, and SH conditions results in variation in the back height measurement (i.e., the back height should decrease as the dummy cast is tilted forward). The observed variability in our study is expected but may indicate a limitation of this metric’s utility in patients with abnormal posture.

The use of a dummy cast is a limitation of this study because the cast may not accurately reflect surface marker movement which would be present in a human subject. Surface marker motion is common to all rasterstereography techniques but good correlation between rasterstereographic and radiographic metrics has been reported [15 Goldberg CJ, Kaliszer M, Moore DP, Fogarty EE, Dowling FE. Surface topography, Cobb angles, and cosmetic change in scoliosis Spine 2001; 26(4): E55-63., 24 Sakka SA, Wojcik A, Macindoe S, Mehta MH. Three-dimensional analysis of spinal deformity. Stanmore, England: IOS Press 1995; pp. 111-5.]. The present study presents a confirmation of the technology and our lab will evaluate the system in a human subject in the near future.

Intra-Observer and Inter-observer ICCs indicate that the MTS is highly reliable for all tested metrics excluding Pelvic Tilt. Lyon et al. assessed QSIS reliability using a random effects variance components model in 200 children with a diagnosis of adolescent idiopathic scoliosis and reported the highest reliability when three scans and three measurements were performed [25 Lyon R, Liu XC, Thometz JG, Nelson ER, Logan B. Reproducibility of spinal back-contour measurements taken with raster stereography in adolescent idiopathic scoliosis Am J Orthop (Belle Mead NJ) 2004; 33(2): 67-70.]. Although our data is not directly comparable to this previous research because only one “subject” was included in our study, we report excellent reliability of the MTS regardless of different investigators, trials, and positions.

CONCLUSION

We conclude that the MTS is a reliable method of newly developed raster stereography in a majority of clinically used parameters. Non-invasive methods of spinal monitoring are necessary to prevent exposure to health risks related to repeated x-rays in patients with scoliosis.

ACKNOWLEDGEMENT

Authors would like to thank Mr. Carlos Marquez, MS of mechanical engineer and Dr. Yu Wang, Ph.D of biomedical engineer for the help of testing.

CONFLICT OF INTEREST

Declared none.

ABBREVIATIONS

ISIS =Integrated Shape Imaging System
QSIS =Quantec Spinal Imaging System
MTS =Milwaukee Topographic Scanner
PSIS =Posterior superior iliac spine
Q-angle =An analog to X-ray’s Cobb angle

REFERENCES

[1] Nash CL Jr, Gregg EC, Brown RH, Pillai K. Risks of exposure to X-rays in patients undergoing long-term treatment for scoliosis J Bone Joint Surg Am 1979; 61(A3): 371-4.
[2] Levy AR, Goldberg MS, Hanley JA, Mayo NE, Poitras B. Projecting the lifetime risk of cancer from exposure to diagnostic ionizing radiation for adolescent idiopathic scoliosis Health Phys 1994; 66(6): 621-33.
[3] Ronckers CM, Land CE, Miller JS, Stovall M, Lonstein JE, Doody MM. Cancer mortality among women frequently exposed to radiographic examinations for spinal disorders Radiat Res 2010; 174(1): 83-90.
[4] Daruwalla JS, Balasubramaniam P, Chay SO. Idiopathic scoliosis. Prevalence and ethnic distribution in Singapore schoolchildren J Bone Joint Surg Br 1985; 67(2): 182-4.
[5] Denton TE, Randall FM, Deinlein DA. The use of instant moire photographs to reduce exposure from scoliosis radiographs Spine 1992; 17(5): 509-12.
[6] Malmström EM, Karlberg M, Melander A, Magnusson M. Zebris versus Myrin: a comparative study between a three-dimensional ultrasound movement analysis and an inclinometer/compass method: intradevice reliability, concurrent validity, intertester comparison, intratester reliability, and intraindividual variability Spine 2003; 28(21): E433-40.
[7] Theologis TN, Jefferson RJ, Simpson AHRW, Turner-Smith AR, Fairbank JCT. Quantifying the cosmetic defect of adolescent idiopathic scoliosis Spine 1993; 18(7): 909-12.
[8] Theologis TN, Fairbank JCT, Turner-Smith AR, Pantazopoulos T. Early detection of progression in adolescent idiopathic scoliosis by measurement of changes in back shape with the integrated shape imaging system scanner Spine 1997; 22(11): 1223-8.
[9] Thometz J, Liu XC, Harris GF. Computerized evaluation of the surface measurement of kyphosis and lordosis in idiopathic scoliosis In: Proceedings of the 20th International Conference of the IEEE Engineering in Medicine and Biology; 1998 Oct 28–Nov 1; Hong Kong. 1998; pp. 2507-8.
[10] Liu XC, Thometz JG, Lyon RM, McGrady L. Effects of trunk position on back surface-contour measured by raster stereophotography Am J Orthop (Belle Mead NJ) 2002; 31(7): 402-6.
[11] Liu XC, Thometz JG, Lyon RM, Klein J. Functional classification of patients with idiopathic scoliosis assessed by the quantec system: A discriminant functional analysis to determine patient curve magnitude Spine 2001; 26(11): 1274-8.
[12] Schulte TL, Hierholzer E, Boerke A, et al. Raster stereography versus radiography in the long-term follow-up of idiopathic scoliosis J Spinal Disord Tech 2008; 21(1): 23-8.
[13] Hackenberg L, Hierholzer E, Pötzl W, Götze C, Liljenqvist U. Rasterstereographic back shape analysis in idiopathic scoliosis after anterior correction and fusion Clin Biomech 2003; 18(1): 1-8.
[14] Hackenberg L, Hierholzer E, Pötzl W, Götze C, Liljenqvist U. Rasterstereographic back shape analysis in idiopathic scoliosis after posterior correction and fusion Clin Biomech 2003; 18(10): 883-9.
[15] Goldberg CJ, Kaliszer M, Moore DP, Fogarty EE, Dowling FE. Surface topography, Cobb angles, and cosmetic change in scoliosis Spine 2001; 26(4): E55-63.
[16] Klos SS, Liu X, Lyon RM, Tassone JC, Thometz JG. Reliability of a functional classification system in the monitoring of patients with idiopathic scoliosis Spine 2007; 32(15): 1662-6.
[17] Thometz JG, Lamdan R, Liu XC, Lyon R. Relationship between Quantec measurement and Cobb angle in patients with idiopathic scoliosis J Pediatr Orthop 2000; 20(4): 512-6.
[18] Thometz JG, Liu XC, Lyon R, Harris GF. Variability in three-dimensional measurements of back contour with raster stereography in normal subjects J Pediatr Orthop 2000; 20(1): 54-8.
[19] Suzuki N, Tezuka M, Toshiaki T. Scoliosis follow-up by back shape analysis: Evaluation of its reliability In: Amico MA, Merolli A, Santambrogio GC, Eds. Three-dimensional analysis of spinal deformities. Amsterdam: IOS Press 1995; pp. 405-8.
[20] Suzuki N, Inami K, Ono T, Kohno K, Asher MA. Analysis of posterior trunk symmetry (POTSI) in scoliosis In: Strokes IAF, Ed. Research into Spinal Deformities 2. Amsterdam: IOS Press 1999; pp. 81-4.
[21] Wojcik AS, Philips GF, Mehta MH. Recording of the back surface and spinal shape by the Quantec Image System: A new technique in the scoliosis clinic J Bone Joint Surg Br 1994; 76: 10.
[22] Morrissy RT, Goldsmith GS, Hall EC, Kehl D, Cowie GH. Measurement of the Cobb angle on radiographs of patients who have scoliosis. Evaluation of intrinsic error J Bone Joint Surg Am 1990; 72(3): 320-7.
[23] Stokes IAF, Moreland MS. Measurement of the shape of the surface of the back in patients with scoliosis. The standing and forward-bending positions J Bone Joint Surg Am 1987; 69(2): 203-11.
[24] Sakka SA, Wojcik A, Macindoe S, Mehta MH. Three-dimensional analysis of spinal deformity. Stanmore, England: IOS Press 1995; pp. 111-5.
[25] Lyon R, Liu XC, Thometz JG, Nelson ER, Logan B. Reproducibility of spinal back-contour measurements taken with raster stereography in adolescent idiopathic scoliosis Am J Orthop (Belle Mead NJ) 2004; 33(2): 67-70.

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"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."


Eduardo A. Castro
(INIFTA, Argentina)

"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."


Kenji Hashimoto
(Chiba University, Japan)

"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."


Daniel Shek
(Chinese University of Hong Kong, Hong Kong)

"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."


Jih Ru Hwu
(National Central University, Taiwan)


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