Given the location (i.e. their entry points, but not their trajectories) of two pedicle screws, we are trying to come up with a way to approximate the sagittal distance of the vertebral foramen to the screws' entry points.

I.e. how far "down" (= towards the patient's belly) do you need to go from the screws' entry points until you're at the same height as the approximate center of the vertebral foramen?

And we're trying to do that for all vertebrae into which pedicle screws could reasonably be placed.

We don't know which screws are placed in the Traditional Trajectory (TT) and which are placed in the Cortical Bone Trajectory (CBT) but assume we can ask that, if necessary.

To further complicate the matter, we don't know anything about the patient (data protection). I.e. no age, sex, height, etc. that could help us estimate this.

We hope that we can somehow leverage the distance between the screws to get some rough estimate for the vertebra's height ("head-to-leg" direction) and depth ("belly-to-back" direction), but so far, I don't see how.

Is there any remotely useful ratio between the width of a vertebra and its height or depth?

And does it help at all if we know which vertebra it is (which we don't, but which we could ask, if necessary)?



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