In my post entitled ‘Nerve Injury Upper Thigh Numbness‘ , I high-lighted the problems of femoral cutaneous nerve compression from hip harnesses and pressure near the front of the hip bone. In fact, I recently heard of an injury persisting for 6 weeks which I attribute to be caused by being tied over a table with the edge pressing into this region. Apparently, no warning symptoms were noticed. Similar problems occur with tight jeans, wide belts etc. due to the pressure.
Jahc provided a link to an excellent video that highlights exactly where the nerve appears to be vulnerable and confirms that the nerve can not only run over ligament but also split and go both over and under.
I can’t help but feel that in subjects where the nerve runs over, a higher susceptibility is likely. It would certainly be wise to palpate the area in question when using a hip harness for suspension. Suspensions bringing pressure from the rope into this area would logically carry the greatest risk, e.g. butt up. It is possible the upright positions might drag the rope into a position where it could compress the nerve.
I would be interested to hear the experience of others as, whilst the vulnerability in this area is not new to me, it is only recently that I have been hearing of injuries. Of course, this is result of the greater popularity of this sort of tie.