Cerebral Palsy maybe/maybe not

Actual example:

How much change in length of the invisible (but actually the functional aspect) line between the hip to ankle? Isn't that just a 1:1 correlation? No. The knee angular changes graphed are “periodic” as it is a rotation effect and not a point to point measurement. Also the functional implication depends on the angle which that linear but invisible Hip-Ankle line makes to the GROUND. Ahhhh. The ground . We have all heard of 'the ground'. We walk on THAT. So, the invisible (and nearly always unmentioned nor measured) hip to ankle line is also a spatial vector which becomes a functional measurement when tracked relative to the ground . It measures what the knee accomplishes .