Your question ... the way you wrote it ... really doesn't make sense. I think you meant the second choice to be "legs straight and knees locked". That configuration is more likely to hurt you, because your knees can't absorb any of the impact, and the shock is transmitted up into your hips and spine.
bent knees ---- a lap
Try walking or jumping with your knees locked. Seriously, does this need to be answered?
In tuck, your knees are bent. In pike, your knees should be straight.
This is normally because of blood clots, if blood clots are chronic in your family then then that is your problem. it may also cause cramps.
The correct alignment for the yoga pose where you lie on your back with your knees bent is to keep your feet hip-width apart and parallel to each other, with your knees pointing up towards the ceiling.
plié
slighty bent
slighty bent
Please state why your knees hurt? Is it an injury? Is it arthritis? It makes a huge difference, so please rephrase your question.
As long as you keep their head above your knees, it won't hurt them.
If a person has an abdominal wound, you should rest their upper half on your bent knees on the ground.