Scoliosis and the Cobb Angle: Novel Radiation-Free Assessment

Part Two of Two

Peer Reviewed

A real time display of the recorded data is presented on the Ortelius800® screen. Upon completion of the examination, the system instantaneously creates a graphical reconstruction of the spine, displaying the calculated angle of deformity (Cobb angle), leg length discrepancy, and additional data on the patient's torso balance (Figure 3a-d).

AP x-ray C1-S1 cobb angle measurements
Figure 3a.
Antero-posterior x-ray of C1-S1 and Cobb angle measurements.

cobb angle measurements
Figure 3b.
Cobb angle measurements obtained using the Ortelius800®.

graphical reconstruction spine
Figure 3c.
Graphical reconstruction of the patient's spine.

graphical representation pelvic shoulder
Figure 3d.
Graphical representation of the pelvic shoulder angle.

Validation Studies of Ortelius800®
Ovadia et al studied 102 adolescent idiopathic scoliosis patients from 3 different medical centers and compared the Cobb values obtained from standard full spinal standing x-rays and measurements obtained with the Ortelius® system (9). The mean thoracic Cobb angle was 17.7 degrees and the mean lumbar angle was 17 degrees. A total of 205 curves were measured in the coronal plane. The authors found a high agreement between the measuring modalities both in the coronal and sagittal planes (Figure 4).

radiographic measurements
Figure 4.

Baron, Dickman, Ephrath, and Floman studied the interobserver variability of the Ortelius® system in 48 scoliotic patients. There was no statistical difference of two different examiners as shown by the paired sign-rank test (Figure 5a-b). Therefore the examiner performing the radiation-free measurement of the scoliotic Cobb angle does not affect the system results (10).

deformity measurements
Figure 5a.

measurement deviations
Figure 5b.

Follow-up of the scoliotic patients with the Ortelius800®, provides the managing orthopedic surgeon with a radiation-free accurate Cobb angle measurement. Although one will still need to obtain the initial standing full spinal x-ray for instance, to detect congenital spine anomalies. This system allows for cutting down the number of x-rays to the necessary minimum. The system provides additional information on torso balance, a 'top view' of the deformity and other features that may shed further insight into the real 3-D nature and biomechanics of the spinal deformity.

In patients managed with braces, the examination is obtained out of the brace. This may still necessitate obtaining an initial radiograph in the brace to assure visualization of proper pad placement and corrective effect of the brace. Caution should be exercised with the Ortelius® system when following a patient with congenital scoliosis.

Ortelius800® has been approved by the US Food and Drug Administration (FDA) and has received the European CE certification.

References

1. Doody M, Lonstein JE, Stovall M, Hacker DG, Luckyanov N, Land CE. Breast cancer mortality after diagnostic radiography: findings from the U.S. Scoliosis Cohort Study. Spine 25:2052-63, 2000

2. Rao PS, Gregg EC. A revised estimate of the risk of carcinogenesis from x-rays to scoliosis patients. Invest Radiol 19:58-60, 1984.

3. Hoffman DA, Lonstein JE, Morin NM, Visscher W, Harris BS 3rd, Boice JD Jr. Breast cancer in women with scoliosis exposed to multiple diagnostic x-rays. J Natl. Cancer Inst 81:1307-12, 1989.

4. Doody MM, Lonstein JE, Stovall M, Hacker DG, Luckyanov N, Land CE. For the US Scoliosis Cohort Study Collaboration. Spine 25:2052-63, 2000.

5. Goldberg MS, Mayo NE, Levy AR, Scott SC, Poitras B. Adverse reproductive outcome among women exposed to low levels of ionizing radiation from diagnostic radiography for adolescent idiopathic scoliosis. Epidemiology 9:271-8, 1998.

6. Levy AR, Goldberg MS, Mayo NE, Hanely JA, Poitras B. Reducing the lifetime risk of cancer from spinal radiographs among people with adolescent idiopathic scoliosis. Spine 21:1540-48, 1996.

7. Mior SA, Kopansky-Giles DR, Crowther ER, Wright G. A comparison of radiographs and electrogoniometric angles in adolescent idiopathic scoliosis. Spine 21:1549-1555, 1996.

8.Schmitz A, Jaeger UE, Koening R, Kandyba J, Wagner UA, Giesecke J, Schmitt O. A new MRI technique for imaging scoliosis in the sagittal plane. Europ Spine J 114-7, 2001.

9. Ovadia D, Dickman D, Fragniere B, Leitner J, Rigo M, Dubousset J. A Non-Invasive Approach for Scoliosis Assessment. Oral presentation, EuroSpine, October 2003. Prague, Czechoslovakia.

10. Baron E, Dickman D, Ephrath H, Floman Y. Radiation-Free Assessment of Scoliosis: Inter-Observer Reliability. Oral presentation, WorldSpine II, August 2003. Chicago, IL.

Updated on: 09/26/12
Lawrence G. Lenke, MD
The search for less invasive means of identifying and evaluating scoliosis and other spinal deformities is important because of the theoretical health risks with multiple x-rays, which are the standard method of scoliosis documentation. The Ortelius800® device is a very specialized and unique way of attempting to obtain detailed information on the presence, location and size of scoliosis deformities and potentially other spinal malalignments such as excessive thoracic kyphosis and others. Being familiar with the device, it is very user-friendly and well-accepted by patients. Ongoing clinical research will attempt to validate its accuracy and usefulness in a routine clinical setting for both screening of scoliosis and follow-up evaluation of documented deformities being observed, braced or having had operative intervention.
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