The usual situation is a multiple redo or infected groin with heavy scarring. Woody is the proper adjective. The common femoral artery may be obliterated or buried in the scar but a small profunda or its major branch may be accessible. Or you just run into it and get bleeding. Rather than bemoan your fate, you may be able to make a purse out of sow’s ear by exposing the artery and sliding in an appropriately sized Argyll shunt. Backbleeding into the shunt means that you haven’t dissected (hopefully) the artery, and now you have control over the surface edge of an artery. You can then clamp the shunt. You can assess your situation and decide that spending another two hours digging out two centimeters of 3mm artery may not be worthwhile, but you also decide that it is important to preserve this vessel.
It is straightforward to anastomose graft to the arterial stump. The shunt keeps you from narrowing the anastomosis, as you are well aware from carotid shunting. While you are doing this, if you have a Rummel tourniquet or vessel loop around the distal external iliac, you can feed the leg via this shunt as long as you remember to have the graft over the shunt. And remove it when you are done.
Another scenario is in revascularizing an intercostal, lumbar artery, or backbleeding posterior origin accessor renal but don’t want to do it right away.