Tendon length shorter than expected

My tendon profile:

If simply calculating the tendon length without the radius, it'd be 70.808 -5.808 =65m

Hence, I expected the actual length (with the radius) to be larger than 65m.

However, Midas is giving 64.85m:

Why is that?

The issue happening here is due to the internal processing of how the tendons are considered.  When a tendon is assigned to any element, internally, the element is divided into 5 parts and forces are transferred at these locations to the element.  The tendon coordinates and tendon lengths are also calculated in accordance with these internal locations for force transfer.
To avoid this discrepancy it is recommended to create a node at the beginning and end of the tendon location as shown by the red circle in the image below.  Once that is done, the tendon length is acceptable.

Kindly let us know if further assistance would be required.