Clinical Perspectives
Addressing the Challenges of Manual Variability in Spinal Assessment
Zeynep Çalışkan
Physiotherapist | Scoliosis & Spine Health Specialist at FİZYOWİSE
In the measurement of the Cobb angle, the vertebrae that show the greatest tilt and the least rotation within the curvature are selected as the upper and lower vertebrae, and the measurement is performed accordingly. However, in some cases, the selection of these vertebrae may vary from person to person. For example, while one evaluator may consider a particular vertebra as the upper or lower vertebra, another may select one segment above or below it.
Ideally, the same vertebrae should be used as reference points for every evaluation of the same curvature. However, in practice, even when the same segments are used as a reference, measurements performed by the same person at different times or by different evaluators may result in values that differ by a few degrees.
This situation may arise because the method relies on manual measurement and can be affected by small technical variations. Consequently, these small differences in angle may lead to questions and uncertainties for patients, their families, and the healthcare professionals performing the evaluation.
Büşra Yıldırım
MSc Physiotherapist | Scoliosis & Schroth Specialist at OSTEOWELL
The degree of scoliosis is determined by measuring the Cobb angle. The Cobb angle measurement is performed by evaluating a PA (posterior anterior) spine X-ray taken while the patient is standing. During the measurement, the upper plate of the uppermost vertebra involved in the curvature and the lower plate of the lowest vertebra involved in the curvature are identified. These vertebrae are the first and last vertebrae that have undergone the most lateral deviation. Tangent lines are drawn to these plates. The angle between the perpendicular lines intersecting these lines is called the Cobb angle. The key point in the correct measurement of the Cobb angle is to correctly identify the upper and lower end vertebrae involved in the curvature.
The main factor in this identification is the classification of the curvature and the selection of the end vertebrae by the specialist performing the measurement. The classification of the curvature is important in determining the first and last vertebrae involved in the curvature. In the literature, scoliosis can be classified differently depending on where it occurs. The assessment of the curvature and the determination of the vertebrae involved in the curvature may vary from one specialist to another. The same specialist may measure the same film at different times with a few degrees of difference.
Today, various programs (such as Surgimap) are used to measure the Cobb angle of scoliosis, but measuring with these programs takes a long time, which makes evaluation difficult. In addition, when determining the end vertebra in these programs, the measurement changes quite quickly with small touches. For these reasons, Cobb angle measurement and determination has become a complex parameter for many specialists and, for many patients, a difficult and anxiety-inducing parameter due to the different mathematical values they hear.