Cobb angle

Cobb Angle

The Cobb angle is a measurement used in orthopedics to assess the severity of a spinal deformity, specifically scoliosis. It is named after Dr. John Robert Cobb, an American orthopedic surgeon who developed the method for measuring spinal curvature in the 1940s.

Definition

The Cobb angle is defined as the angle between two intersecting lines drawn perpendicular to the endplates of the two most tilted vertebrae in a spinal curve. It is measured on a standing X-ray image of the spine, typically in the frontal (anterior-posterior) plane. The lines are drawn parallel to the endplates of the vertebrae, and the angle is measured using a protractor or specialized software.

Clinical Significance

The Cobb angle is an essential tool in diagnosing and monitoring the progression of scoliosis. It provides a quantitative measurement of the degree of spinal curvature, allowing healthcare professionals to determine the appropriate treatment plan for each patient. The angle is measured in degrees, with higher values indicating a more severe curvature.

Treatment Guidelines

Treatment decisions for scoliosis are often based on the Cobb angle measurement. The guidelines for treatment vary depending on the age of the patient, the severity of the curve, and other factors. Generally, curves with a Cobb angle of less than 25 degrees are considered mild and may only require monitoring. Curves between 25 and 40 degrees may require bracing, while curves greater than 40 degrees may require surgical intervention.

Limitations

It is important to note that the Cobb angle measurement has some limitations. It is a two-dimensional measurement and does not account for the rotational component of the spinal deformity. Additionally, the measurement can be affected by the positioning of the patient during the X-ray, as well as the accuracy of the radiographic technique used.

References

1. Cobb JR. Outline for the study of scoliosis. Instr Course Lect. 1948;5:261-275. 2. Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Effects of bracing in adolescents with idiopathic scoliosis. N Engl J Med. 2013;369(16):1512-1521.

See Also

• Scoliosis
• Orthopedics
• Spinal Deformity
• X-ray
• Bracing
• Surgical Intervention