Norberg Angle

The Norberg Angle is usually used to assess hip joint laxity and detect hip dysplasia. This measurement requires a radiology image of the patient’s pelvis. Select the Norberg Angle measurement from the Advanced Measurement menu and assign the left mouse button to it.

Start the measurement by marking the three points on the articular surface of the left Caput Femoris.

Mark the three points on the articular surface of the left Caput Femoris (outside of the Fovea Capitilis). Regardless of the order, make sure to mark the most cranial point, the most caudal point and the midpoint of the femoral head. A circle will be automatically constructed based on the three placed points.

The image below depicts the typical placement of the three points on the articular surface of the left Caput Femoris.

Continue by marking the three points on the articular surface of the right Caput Femoris.

Mark the three points on the articular surface of the right Caput Femoris (outside of the Fovea Capitilis). Regardless of the order, make sure to mark the most cranial point, the most caudal point and the midpoint of the femoral head. A circle will be automatically constructed based on the three placed points.

The origos of the two circles will also automatically be connected by a line, specifying the initial side of the angles yet to be constructed.

The image below depicts the typical placement of the three points on the articular surface of the right Caput Femoris.

Calculate the left Norberg Angle measurement by marking a line on the effective edge of the left Acetabularis bone.

Mark a point near the left Caput Femoris and drag it along the effective edge of the left Acetabularis bone, forming the terminal side of the left Norberg Angle.

The drawn line must be a tangent to the effective edge of the left Acetabularis bone. The value and arc of the angle is automatically calculated.

The image below depicts the typical placement of the line and the calculated Norberg Angle measurement.

Calculate the right Norberg Angle measurement by marking a line on the effective edge of the right Acetabularis bone, completing the entire advanced measurement.

Mark a point near the right Caput Femoris and drag it along the effective edge of the right Acetabularis bone, forming the terminal side of the right Norberg Angle.

The drawn line must be a tangent to the effective edge of the right Acetabularis bone. The value and arc of the angle is automatically calculated.

The image below depicts the typical placement of the line and the calculated Norberg Angle measurement.

Modify the position of each point marked on the Caput Femoris or the points of the tangent to automatically recalculate the Norberg Angle.