Scoliosis and the Cobb Angle: Novel Radiation-Free Assessment
Part Two of Two
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).
Antero-posterior x-ray of C1-S1 and Cobb angle measurements.
Cobb angle measurements obtained using the Ortelius800®.
Graphical reconstruction of the patient's spine.
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).
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).
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.
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