Yes, I go with this. Sometimes the more gruesome details are relevant to a story, but I'm not usually looking for that myself.
That is the extra spice here. He is not taking advantage of a woman made vulnerable entirely with nails or ropes. She has spread her own legs, she has chosen to make herself vulnerable this way to ease the pain of her nails and straining arms. She holds this position voluntarily, and suffers this indignity as a result.
Maybe she even takes some pleasure from it, trembling with the strain and building pressure.
She will probably pay the price later.
Will they nail her feet soon? This will relieve the pain of her awkward pose, but will give her new agony to deal with.