Technically, it can be considered amputations.
Even asked the artist if the “intact” marine from Quake is being turned into sexy component for Strogg facility or transformed into Iron Maiden. Mika the artist implied the former.
https://www.pixiv.net/en/artworks/49506268
In honesty, part of me wonder if there might have been Guro explosion if female marines were implemented in Quake 4. Quake 2; however, did implied that female were processed by sizable victims included female Marines and Iron Maidens may have been one of their results.