@deedles7088 A question that your surgeon could answer is to explain how the spinal cord moves and shifts inside the fluid of the spinal canal as you change body, back or head/neck position. Imagine a garden hose and a rope inside that represents your spinal cord. Now bend the rope and make a curved loop with it. The rope must move inside because of the change in diameter of the curve. If your cord is tethered, it will cause pressure when you try to tug on it or bend it. Surely that must cause some symptoms to increase because nerves do not like to be stretched.

There is probably more complexity to your case than my simple explanation. The lumbar spine is not as flexible as the cervical spine because the neck can move in a lot of ways. Your surgeon should be able to explain how tethering affects the cord in different areas and why it produces symptoms as it pulls on the cord and nerve roots within the boney spaces (foramen) between the vertebrae. They may possibly be some stenosis around the nerve roots too.