Arm positioning and postural sagittal variation: are kyphosis and lordosis measurements using x-ray reliable?

Background X-rays are the gold standard evaluation in scoliosis, and this is considered true also for sagittal plane deformities. While it is very well known that posture can change scoliosis curves, this has never been verified for the sagittal plane. In the case of sagittal alignment, it is even more important because to see the spine, there is the need to move the arms from the resting physiological position to a forward position, which may change spinal posture. Today there is not a universally accepted standard for arm positioning during radiographs, nor is it known how it influences spinal measurements. Surface devices may possibly be more reliable measurement instruments than radiographs because they allow the patient to maintain the normal position of their arms. Comparing the two methods is difficult because it would not be ethical to expose patients to repeated doses of x-ray. Surface methods may be tested using these methods, however.