While the original film, directed by George Miller, leaves this aspect of her story largely to the audience's imagination, there is anticipation for more concrete answers in the upcoming prequel focused on Furiosa.

The Furiosa prequel, also helmed by George Miller, promises to delve into the origins and earlier life of this compelling character. This film is expected to provide much-needed context and backstory, potentially including the circumstances that led to the loss of her arm. Given Miller's storytelling style, it's likely that the revelation will be both visually striking and emotionally resonant, fitting seamlessly into the gritty and intense world of "Mad Max."

The prequel offers a unique opportunity to explore the character's formative experiences, shedding light on how she became the formidable warrior seen in "Fury Road." The loss of her arm and her adaptation to a mechanical replacement could be a pivotal plot point, symbolizing her resilience and determination in the face of adversity. This aspect of her story is not just a physical attribute but a significant part of her identity, reflecting her survival and adaptability in a hostile world.

In summary, while "Mad Max: Fury Road" left much of Furiosa's history unexplained, including the loss of her arm, the upcoming prequel dedicated to her character is anticipated to fill in these gaps. This narrative decision aligns well with the storytelling approach of the Mad Max franchise, where character backstories are often revealed gradually, adding depth and richness to the cinematic universe.