Cobb Angle insight from Dr. Morningstar

I thought I would share the contents of a facebook post by Treating Scoliosis, quoting Dr. Morningstar with some wonderful insight on the Cobb Angle.

“Is It Time to Throw Out Cobb Angle Measurements for Scoliosis?
By Dr. Mark MorningStar

Anyone who has scoliosis knows what a Cobb angle is. Physicians and therapists who treat scoliosis know what a Cobb angle is. But, many people don’t realize that the Cobb angle is over 80 years old. In 80 years we haven’t bothered to implement any better, more accurate, and more relevant measurement methods. Yes, there are better methods.

The Cobb angle is a simple measurement that provides only one piece of information: the amount of lateral bending on x-ray. Now here’s the ironic part: scoliosis is not a lateral bending deviation, but a rotational and translational one. Most current scoliosis researchers agree that scoliosis is a 3-dimensional spine deformity, yet the Cobb angle only measures 2 dimensions. Therefore, it is impossible for the Cobb angle to complete information as to the status of the scoliosis.

Aside from the utter lack of validity for the Cobb angle, the Cobb angle value is almost completely arbitrary. Ask 5 different orthopedic surgeons when a scoliosis should be surgically treated, and you just might get 5 different answers. Some say 40 degrees, some say 60 degrees, and some approach it on a case by case basis. Some scoliosis research suggests that the surgical outcome is the same when the scoliosis is measured between 70 to 100 degrees, as compared to operating between 40 and 70 degrees.

Until a better measurement is universally accepted as the gold standard for scoliosis measurement, we will be relegated to using it merely for interprofessional communication. I believe the shift away from Cobb angle will begin to occur when physicians begin placing greater emphasis on the health of the patient and not only the cosmetic impact (although this is important). Many outcome assessments can be used other than Cobb angle to measure the impact of scoliosis on the health of the patient, such as pain level, breathing function, digestive function, psychological health, mobility, and activities of daily living.

With all of the technology available, we should be moving away from using the Cobb angle. It is outdated, has a low level of reproducibility between doctors, and has virtually no validity. Surface topography, 3D posturography, MRI, and spinal ultrasound have all been able to provide more relevant information about the scoliosis deformity.

Since the Cobb angle was first illustrated, women won the right to vote, the Great Depression came and went, we fought in a second world war, and we put a man on the moon. Yet for some reason, we continue to use this basic radiographic assessment of scoliosis. This may well be due to its simplicity, but if it provides no real valid information, why do we use it at all? Instead, why not use rotational measurements (several have already been developed)? Rotational measurements provide much more useful clinical information, such as the impact of rib cage rotation, the position of and torsion on the spinal cord itself, and an evaluation of the active spinal mechanics and whether they are normal or abnormal.

With so many other outcome assessments from which to choose, why in the world do we continue to use a radiographic assessment that is almost as old as x-ray technology itself?”

For more insight from Dr. Morningstar, check out his new book, Scoliosis And ARC3D Therapy.    I am currently in the process of reading this book, and will do a full write up when I am finished.  In the meantime, it is good reading, with some great explanations of the basics of Scoliosis.

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