chupacabras acheronsis, had they hit her in the head, for instance, baby Queen would have remained intact... Moreover, as A^3 suggests, creature can gestate even in the dead body (reference to ox's chestburster, assemly cut).
Yes, you're right, Xenomrph, they just could have to cripple her of free walking by injuring as wel, and, would Ripley survive the surgery, incessant company would have two limping onlookers to answer their questions :-)