Mutilated limb (Fallout 3)

Mutilated limbs are a miscellaneous item in Fallout 3 and Fallout: New Vegas.

Characteristics
Mutilated limbs in Fallout 3 are useful only as either Rock-It Launcher ammunition or as possible decoration for My Megaton house or the Tenpenny Tower Suite. Through simple observation of their physical appearance and the places you most frequently find them, it can probably be assumed they are the discarded portions of humanoids the super mutants have eaten. They are randomly generated into each gore bag.

In Fallout: New Vegas they serve no purpose except for decoration

Locations
Lootable mutilated limbs can be found in gore bags, which are almost always found in super mutant camps and sometimes in raider camps.

In Fallout: New Vegas mutilated legs and organs can be found at the REPCONN Test Site, specifically in the large room with the metal stairs leading to Jason Bright and the Bright Brotherhood. In addition, there are some gore bags with mutilated limbs on the ground near the fishing boat in Lake Mead.