The neck-shaft angle is the deviation of the femoral neck from the femoral diaphysis, where axes of both structures are co-planar. This is usually measured in a two-dimensional radiograph taken in the antero-posterior (AP) view, which is assumed to be perpendicular to the plane containing the femoral diaphysis and neck. In three dimensions, this projection plane is defined as the plane that contains a line defining the diaphysis and the centre of the femoral head. Joining the centre of the femoral head to a reference point in the femoral neck provides a vector describing the femoral neck. The neck-shaft angle is calculated as the angle between the femoral neck vector and the diaphyseal vector in the plane that contains the diaphyseal vector and the centre of the femoral head. Neck Shaft Angle is in active development; your mileage may vary.
- Usage
- Place point ROIs on the femoral head, adding them to the ROI Manager by hitting [t].
- Note the first and last slices that contain diaphysis
- Run Neck Shaft Angle
- Alter options as needed
- Click on the centre of the femoral neck
- Click OK to finish logging angles
- Input
- An image stack
- Point ROIs logged to the ROI Manager
- Clicks on the centre of the femoral neck
- Options
- Shaft Start Slice: First slice that contains diaphysis
- Shaft End Slice: Last slice that contains diaphysis
- HU Calibrated: Checked if image is HU calibrated
- Bone Min: Low threshold in either uncalibrated greys or HU
- Bone Max: High threshold in either uncalibrated greys or HU
- Calculate curvature: Estimate the radii and centres of the circles that best fit the slice centroids in the frontal and sagittal planes.
- Output
- M-L radius: radius of the circle fitting slice centroids in the mediolateral plane
- M-L centre X: X-coordinate of the centre of the best-fit circle in the mediolateral plane, relative to the centroid
- M-L centre X: Y coordinate of the centre of the best-fit circle in the mediolateral plane, relative to the centroid
- Cr-Ca radius: radius of the circle fitting slice centroids in the craniocaudal (sagittal) plane
- Cr-Ca centre X: X-coordinate of the centre of the best-fit circle in the craniocaudal plane, relative to the centroid
- M-L centre X: Y coordinate of the centre of the best-fit circle in the craniocaudal plane, relative to the centroid
- Angle: Neck-shaft angle in radians
- Skew: Angular deviation of the neck vector from the A-P projection plane
This file last modified 1345hrs 29 May 2020 © Michael Doube 2004-2025 :: Designed to be interoperable and standards-compliant.
